Compare Packaging Material Cost Per Square Inch

Compare Packaging Material Cost Per Square Inch Without Guessing

I still remember a client in Los Angeles who swore he had found the cheapest quote for Custom Printed Boxes. The sheet price looked great at $0.18 per unit for 5,000 pieces. Then we added ink coverage, a 1.5 mm board upgrade, die-cut waste, and a 7% trim loss from a messy dieline. The “cheap” option ended up 18% more expensive on the finished run. That’s why I tell buyers to compare packaging material cost per square inch the right way, or you end up paying for paper confetti and supplier optimism.

Plain sheet price is a trap. Roll price is a trap too. A serious buyer needs to compare packaging material cost per square inch using usable area, conversion loss, print coverage, and finishing. I’ve seen a $0.21 kraft board quote beat a $0.17 coated board quote once we added foil stamping and a 12% scrap allowance. The cheaper raw sheet lost. Which is hilarious in the worst possible way, because everyone loves to brag about a low quote until the invoice shows up and laughs back. I’ve had that exact conversation in a Shenzhen office at 9:40 p.m., with lukewarm tea and a calculator that deserved a raise.

Here’s the simple definition I use in supplier calls: take the total cost of the packaging material and all required conversion steps, then divide by the usable square inches that actually become the finished package. Not the marketing sample. Not the outer carton fantasy. The real piece that ships. If you want to compare packaging material cost per square inch, you need an apples-to-apples basis, or you’re just entertaining yourself with bad math. A 4 x 6 inch insert with a 0.5 inch glue tab is not the same thing as a 4 x 6 inch flat print area, no matter how confidently somebody says it is.

The hidden cost drivers show up fast once you’ve spent time on a factory floor. Material thickness changes yield. Coating affects ink adhesion and coverage. Die-cut complexity increases waste. Tight registration on branded packaging adds setup time. Even a slightly fussy fold on retail packaging can slow a line enough to change labor cost by cents per unit, which matters when you’re ordering 10,000 or 50,000 pieces. That’s not theory. I watched a Guangzhou line lose nearly two hours because a tuck flap was off by 1.2 mm and the operator had to stop to avoid creasing the panel. I was standing there thinking, “Great, two hours lost because one flap had commitment issues.”

“Cheap packaging is often expensive packaging with the middle parts hidden.” That’s what I told a cosmetics buyer after her second quote arrived with three separate finishing charges no one mentioned in the first email. The job was for 8,000 units in Melbourne, and the “extra” charges added $412 before freight even showed up.

Think of this as a buying decision, not a design exercise. Packaging design matters, sure. But if your spec can’t be quoted consistently, the design is just a pretty way to waste money. I’ve negotiated with suppliers who could quote a gorgeous rigid box in five minutes and then quietly add a lamination fee, a magnetic closure fee, and a packaging insert fee later. No surprise there. The factory wants scope clarity. You should want the same thing. In Dongguan, one converter quoted a rigid setup at $0.86 per unit for 3,000 pieces, then tried to add $240 for “extra handwork” after proof approval. We fixed it. Because I am apparently allergic to nonsense.

So the rest of this is built around a method buyers can actually use. I’ll show how to compare packaging material cost per square inch without relying on vague “good/better/best” vendor language, and without pretending the raw substrate is the whole story. If you’re buying product packaging, retail packaging, or promotional mailers, this is the method that keeps your budget honest. It also keeps your procurement team from celebrating a fake win at $0.03 a unit while ignoring a $180 tooling fee hiding in the corner.

Packaging Material Types and What Actually Changes Cost

Before you compare packaging material cost per square inch, You Need to Know what actually sits in the quote. Paperboard, kraft, corrugated, rigid chipboard, PET, PP, and specialty films all behave differently in production. They also carry different conversion risks. A supplier can quote the same outside dimensions and still end up with wildly different finished costs because the substrate, the coating, and the press setup are not remotely the same job. I’ve seen two factories in Guangzhou and Ningbo quote the same 200 x 120 x 45 mm box with a $0.11 gap just because one used standard stock and the other used an oversized sheet.

Paperboard is usually the first stop for folding cartons and mid-range package branding. A 300gsm C1S board with matte aqueous coating often prints beautifully and cuts cleanly. A 350gsm C1S artboard with gloss lamination costs more, but it gives better stiffness for cosmetics, tea, and supplement cartons. It’s popular because it balances presentation and cost. Kraft paper brings a natural look and often lower material cost, especially for simple mailers, sleeves, and wraps. I’ve seen kraft win on price in runs where the artwork was one-color black and the structure was simple. Once you ask for dense full-bleed graphics, the math changes because coverage and waste go up. For a 5,000-piece sleeve run in Hanoi, the jump from one-color to full-coverage artwork added about $0.02 per unit just in print time and ink.

Corrugated cardboard is the workhorse for shipping and protective boxes. It’s not usually the prettiest, unless you dress it up, but it protects product well and can be efficient at scale. A single-wall E-flute or B-flute box can be very competitive if the priority is compression strength and shipping cost. If the job is retail display packaging, corrugated might need a liner or print upgrade to look respectable on shelf. That adds cost. Obviously. A brown E-flute mailer with black flexo print might land around $0.24 per unit for 5,000 pieces, while a white-lined version with a better finish can move closer to $0.31. Same shape. Different invoice.

Rigid chipboard is a different animal. It feels premium because it is premium in structure, but it also adds cost in board weight, hand assembly, and sometimes magnet or ribbon hardware. For luxury custom printed boxes, rigid often makes sense because it reduces the need for outer gift wrap and can raise perceived value. In one factory visit in Dongguan, I watched a team hand-wrap 3,000 rigid two-piece boxes with paper and corner wraps. Beautiful result. Labor heavy. The quote reflected that labor, not just the board. I remember asking the production manager how many people were on the wrapping line, and he just smiled like, “Enough to make your spreadsheet cry.” He wasn’t wrong.

PET and PP are common for clear packaging, clamshells, and display windows. They are strong, consistent, and often predictable in conversion, but they are not automatically cheap just because the sheet looks thin. Thermal behavior, forming, and environmental fee structures can all change your final cost basis. A 0.3 mm PET sheet can be quoted at around $0.0016 per square inch, but thermoforming, scoring, and cut tolerance can push the finished price closer to $0.0030 per square inch. Specialty films add even more variables: barrier layers, seal performance, and substrate consistency. If you need shelf life or moisture resistance, the lowest raw price may be useless if the package fails during transit. A barrier film in Suzhou might cost $0.42 more per 1,000 units, but it can save a whole pallet of returns. That tradeoff is not cute, but it is real.

Three things change usable square-inch cost more than most buyers expect: density, thickness, and consistency. GSM matters for paper. Caliper matters for board and film. Consistency matters because unstable stock creates more waste during die-cutting and folding. A board that varies by 0.05 mm across a run can cause scoring issues. That is how a quote that looked sharp on paper turns into scrap in the bin. I’ve seen a carton line in Shenzhen slow down for 47 minutes because a 300gsm board batch was reading closer to 318gsm on the caliper gauge. That is the kind of “small” variation that becomes a very expensive mood.

Here’s another reality from supplier negotiations: minimum run sizes and stock availability can wipe out material savings fast. I’ve had a supplier in Shenzhen offer a lower unit price on coated board, then reveal that the stock only came in pallets of 5,000 sheets and freight added $280 to the job. Another time, a kraft paper option looked cheaper until we discovered the standard stock width forced a 9% yield loss. The quote didn’t lie. It just didn’t tell the whole story. That part is almost always the problem, by the way. The quote is technically correct and strategically annoying.

If you want to compare packaging material cost per square inch honestly, you have to treat the substrate as only one part of the finished system. Print-friendly materials often cost less to decorate. Protective materials may save you on damage claims and returns. The raw sheet is just the beginning. The finished package is what gets paid for, shipped, and judged by the customer. A $0.015 per unit board change can look tiny until you multiply it across 25,000 pieces and a three-month reorder cycle. Then it stops being tiny very quickly.

Compare Packaging Material Cost Per Square Inch by Specification

If you want a real comparison, start with the flat dieline, not the outside box dimensions. That’s where most people go wrong. A 6 x 4 x 2 inch carton does not mean you are buying 48 square inches of material. Once you include glue tabs, fold panels, dust flaps, and print bleed, the usable area is usually larger. I’ve seen buyers compare two box styles without counting the closure flap. That kind of mistake makes every quote look wrong, when the quote is not the problem. On one 7,500-piece run in Dongguan, a missing 0.75 inch dust flap changed the estimated material use by 11.4 square inches per unit. Suddenly everyone cared about geometry.

To compare packaging material cost per square inch properly, calculate the flat area of each dieline and use the same definition across all options. For folding cartons, that means panel sizes, flap sizes, and any extra gussets. For mailers or sleeves, it means the full printable surface plus waste from trim and machine setup. For corrugated boxes, include flute direction when it affects panel sizing and stacking strength. If you ignore these details, you are comparing air. Expensive air. If one supplier quotes a die-cut sleeve at 38.2 square inches and another quotes by finished face only, stop the conversation and reset the math.

Board thickness, flute type, laminate, embossing, and spot UV all affect actual square-inch cost. A 350gsm artboard with soft-touch lamination may cost more than 300gsm plain board, but it can eliminate the need for an additional insert or a secondary label. A B-flute corrugated mailer might be better for shipping efficiency than a thicker rigid setup, depending on transit distance and damage risk. And yes, spot UV can add a premium that looks small until you spread it over a 5,000-piece run. For example, a spot UV accent on a 4-panel cosmetic box can add $0.04 to $0.07 per unit, while a full soft-touch lamination may add another $0.03 to $0.05 depending on the city, the press, and whether the stock is in Guangdong or shipped in from Zhejiang.

I keep a simple framework for quote comparison. It’s boring. It works.

• Raw material price — the base sheet, board, film, or roll.
• Conversion loss — trim waste, die waste, setup spoilage, and press start-up.
• Printing cost — number of colors, coverage level, and press type.
• Finishing cost — lamination, embossing, foil, varnish, cutting, folding, glue.
• Scrap rate — what the supplier assumes will be lost before shipping.

Now, the part buyers like because it makes the math visual: build a one-page spec sheet before requesting quotes. Include dimensions, material grade, thickness, print coverage, finish, target quantity, and delivery location. If you send “need box quote” and hope for magic, you’ll get a quote shaped by the supplier’s favorite stock size, not your actual cost target. I’ve seen a carton quote swing by $0.06/unit just because one supplier used a standard die size and the other had to create a new tool. That kind of gap makes everyone pretend they weren’t confused five minutes earlier. For a project shipping to Austin, the freight alone changed the delivered price by $190 because the carton pallet count was different. That matters.

Below is a plain comparison format you can use to compare packaging material cost per square inch side by side. I’m not pretending these are universal prices. They aren’t. Freight, order size, and finish all move them. But the structure is the point. The sample pricing below reflects typical factory quotes from Guangzhou, Dongguan, and Ningbo for 5,000-piece orders, not showroom fantasy.

That table is not a quote sheet. It’s a decision tool. You still need actual supplier numbers. But it gives you a structure to compare packaging material cost per square inch without getting hypnotized by a tiny unit price that ignores the rest of the job. On a 10,000-piece order, a difference of $0.0004 per square inch can turn into a $280 swing across the run. Tiny decimals love to look harmless until they multiply.

One more thing from the factory floor: print-friendly materials are not always the cheapest finished package, and protective materials are not always the heaviest cost. I once saw a simple kraft mailer lose to a printed board sleeve because the mailer needed extra reinforcement tape, while the sleeve slid into a pre-packed kit with zero rework. Different workflows. Different waste. Different total spend. Different headaches, too. I’d rather solve the spreadsheet problem than dig tape fibers out of a production floor for the third time. That happened in Ningbo, and my shoes still remember it.

That’s why I keep repeating the same instruction to procurement teams: compare packaging material cost per square inch based on finished function, not just substrate category. If the package protects better, assembles faster, or prints cleaner with fewer passes, the cheaper raw sheet may actually cost more in the end. You’re not buying paper. You’re buying a packaged outcome. A very specific one, usually with a delivery window of 12 to 18 business days after proof approval if the factory is in Guangdong and the finishing line isn’t slammed.

Pricing, MOQ, and How to Avoid Paying for Waste

MOQ is where a lot of buyers get burned. They see a lower unit price at 10,000 pieces and think they’ve won. Then they realize they only needed 3,000 units, or they don’t have storage, or the product refreshes next quarter. So yes, the quote is lower on paper. But the total cash outlay is higher, and the risk sits on your shelf like a very expensive paperweight. I’ve seen a team in Sydney save $0.011 per unit by jumping to 20,000 pieces, only to pay for warehouse overflow six weeks later. That’s not savings. That’s a storage invoice with better branding.

To compare packaging material cost per square inch properly, you have to see how MOQ changes the economics. A supplier may spread setup costs across a larger run, which lowers unit cost. That’s normal. But if the MOQ forces overbuying, the effective cost rises because you are tying up cash, adding storage, and increasing obsolescence risk. I’ve had clients save $0.012 per unit and lose thousands when they ended up scrapping old artwork six months later. That’s a brutal little math lesson nobody puts in the sales deck. One beauty brand in Seoul burned through $1,150 in obsolete sleeves because the ingredient panel changed after an import rule update.

Setup charges matter too. Plates, cutting dies, embossing tools, proofing fees, and color matching can turn a “good” quote into a weak one. A realistic quote should show these separately. If not, ask. I once negotiated with a supplier who buried a $180 die fee under a vague “tooling support” line. Cute wording. Not helpful. We removed it and pushed the cost into the run pricing where it belonged. You can almost hear the sigh from the sales rep, but that’s fine. I’m not funding their vague vocabulary habit. If a factory in Suzhou wants $95 for plates and $140 for a new die, I want those numbers visible before I sign anything, not after.

Here’s the quote behavior I watch for:

1. Low unit price, high setup fee — good only if the run is large enough.
2. High freight, low material price — common when suppliers ship from a distant plant.
3. “Standard stock” assumption — cheaper if your spec fits; expensive if it doesn’t.
4. Unknown scrap allowance — a hidden buffer that quietly inflates the cost.
5. Extra finish line items — lamination, coating, foil, and varnish listed after the fact.

If you want to compare packaging material cost per square inch like a professional, ask these questions every time:

• What is included in the unit price?
• What triggers extra charges?
• What scrap rate did you assume?
• Is the material standard stock or special order?
• How are setup costs spread across the MOQ?
• Does freight include residential delivery, liftgate, or import fees?

Those questions save money because they force scope clarity. Suppliers hate surprises as much as you do, even if they sometimes create them. I’ve seen padded quotes where the supplier assumed a 10% spoilage rate on a clean folding carton job that only needed 3%. Why? Because the buyer didn’t push back. If you do push back, politely but firmly, the quote usually gets sharper. Funny how that works. In one case, a Ningbo supplier dropped a $0.05 packaging allowance simply because we specified that artwork was final and print-ready.

There’s another angle: order volume changes pricing tiers. Ask for three levels every time if you can. For example, 3,000, 5,000, and 10,000 units. That lets you see the slope of the price curve, not just the final number. Sometimes the incremental savings between 5,000 and 10,000 are tiny, which means you should stop at 5,000 and keep cash in the bank. Other times the larger run is worth it because the setup is expensive and the unit savings are real. Either way, you’re using data, not hope. A factory in Foshan quoted one rigid box at $1.14 for 3,000 units and $0.97 for 10,000 units; the math only made sense if the launch sold through in under 90 days.

And yes, a cheaper material can still cost more after printing and finishing. I’ve watched that happen on branded packaging with heavy coverage and foil. The supplier quote for the raw board was lower, but the ink sat badly, the finishing pass slowed down, and waste climbed. The final square-inch cost was higher. That’s why I tell buyers to compare packaging material cost per square inch from the finished outcome back to the substrate, not the other way around. A $0.02 raw sheet advantage means nothing if the line loses 6% more yield.

Process and Timeline for Comparing Material Quotes

The fastest way to get clean quotes is to send clean data. That means a dieline, final dimensions, artwork coverage, material spec, finish, tolerance, quantity, and delivery location. If you leave out the finish or the tolerance, the supplier will fill the gap with assumptions. Those assumptions are where comparison errors breed. I’ve had quotes come back from Dongguan, Shenzhen, and Ningbo that differed by 14% on the same structure simply because one buyer brief said “matte finish” and another said “matte lamination, anti-scratch, 1-side only.” Same box shape. Different universe.

Here’s the process I use when I need to compare packaging material cost per square inch across suppliers.

1. Prepare the dieline with accurate flat dimensions and glue tabs.
2. Specify the substrate with GSM, caliper, flute, or film thickness.
3. List printing details such as color count, coverage, and any PMS matches.
4. State finishes clearly including matte lamination, gloss varnish, embossing, or foil.
5. Confirm quantity tiers so pricing can show the curve across different MOQs.
6. Request sample timing and production timing separately.
7. Ask for landed cost if freight or import charges matter to your budget.

Sampling timelines and production timelines are not the same. A prototype may take 5 to 8 business days if the die is simple and material is in stock. A production run may take 12 to 18 business days after proof approval, depending on press capacity and finishing load. If someone tells you both happen “quickly,” they are skipping details. And details are the whole point. For a carton made in Guangzhou, I usually tell clients to expect 2 business days for the digital proof, 3 to 5 business days for a physical sample, and 12 to 15 business days for volume production after proof sign-off if the board is already in stock.

Comparing sample quality against the quoted cost is where buyer judgment matters. A sample on 350gsm board can look excellent, but if the quote assumed 300gsm, the sample may have changed the entire cost basis. Check the spec sheet. Match the sample to the quote. Then compare the actual finish: ink density, score quality, fold memory, glue bond, and color drift. This is where experience beats guesswork. I’ve rejected more than one “perfect” sample because the fold cracked at the score line after the second open-close test at room temperature in a New Jersey warehouse.

I’ve had one supplier in Shenzhen send a pristine sample wrapped in all the right finishing. The quote later came back lower because the sample had been made with a premium stock they didn’t plan to use in volume. Useful? Sure. Honest? Not really. We caught it because the sample sheet thickness was 1.7 mm and the quote referenced 1.4 mm. That 0.3 mm changed everything, including folding resistance and carton feel. The sample was basically wearing a tuxedo to the quote meeting.

Delays usually come from the same places: artwork revisions, material shortages, and approval bottlenecks. If your brand team changes a Pantone after proof approval, expect the clock to restart. If a specified kraft paper grade is out of stock, a supplier may substitute a similar grade with different density. And if your legal team is reviewing compliance text, production sits. None of that is mysterious. It just needs planning. I had one project in Hong Kong lose four business days because the ingredient list moved by 3 mm and the barcode zone needed to be redrawn.

For buyers handling product packaging programs across multiple SKUs, I recommend keeping a master quote folder with the same format every time. That makes it much easier to compare packaging material cost per square inch across runs, seasons, and vendors. You can spot when a quote has drifted by 8% because freight changed, or because a supplier quietly swapped in a different board line. It also helps when you are comparing a factory in Guangdong with one in Ho Chi Minh City, where the labor and freight structures are never identical, no matter how pretty the spreadsheet looks.

If sustainability is part of your buying criteria, I also recommend checking material certifications and transit impact. Organizations like FSC provide standards for responsible forestry, and the EPA sustainable materials management resources are useful if your team cares about waste reduction and material efficiency. I’ve found those references help procurement teams explain tradeoffs internally, especially when a slightly higher-cost substrate reduces waste or improves recyclability. If the board is FSC-certified and the supplier can show the chain-of-custody number, that’s a real sourcing detail, not a marketing sticker with good lighting.

Why Choose Us for Material Cost Comparison

Custom Logo Things is built for buyers who want numbers, not theater. We help clients compare real packaging options across different substrates, print methods, and finishes so they can compare packaging material cost per square inch on a true like-for-like basis. No pretty quote hiding a dozen add-ons. No “we’ll see once production starts.” That kind of answer belongs in a bad sitcom, not in procurement. If a supplier can’t explain a $0.13 unit price down to the board grade and finishing line, I assume they’re selling hope in a PDF.

When I work with buyers, I usually start by separating the job into three buckets: material, conversion, and logistics. That makes it much easier to compare options for custom printed boxes, mailers, wraps, and retail packaging. I’ve spent enough time in factories to know that the cheapest raw board rarely wins if the line slows down or waste spikes. So we look at the whole package: board grade, print process, finish, assembly, and shipping impact. A converter in Dongguan once quoted a nice-looking carton at $0.29 per unit, but the 15% scrap assumption and pallet freight pushed it to $0.37 landed. The spreadsheet had feelings after that.

We also help reduce waste through better sizing. I’ve seen dielines trimmed by 2 to 4 mm per side without hurting structure, which saves material across a 5,000-piece run. That may sound tiny. It isn’t. On large programs, tiny becomes money quickly. If you can remove one unnecessary panel, reduce a flap, or choose a more efficient board size, you improve the square-inch equation immediately. A 3 mm reduction across a 220 x 160 x 50 mm mailer can save enough stock to matter on every reorder, especially when the run repeats monthly.

Our supplier coordination matters too. I’ve negotiated with mills and converters where the first quote was padded because the scope was vague. Once we clarified the spec, the pricing tightened. That is part of the value: we know what to ask, what’s standard, and what’s a bogus extra. Buyers want quote transparency because surprises always land on their desk later. Fair enough. I’d rather catch the extra $65 plate fee before the PO goes out than explain it to finance after the shipment clears customs.

We also cover a wide range of Custom Packaging Products, which helps when you need to compare multiple packaging formats for one brand. Maybe your subscription box needs corrugated outer cartons, but your retail launch needs coated paperboard sleeves and inserts. Same brand. Different cost profile. Different workflow. Better to compare them in one conversation than three disconnected ones. That’s especially useful when your US team is in Chicago, your merch team is in Toronto, and your factory is in Shenzhen. One quote format saves everyone from rewriting the same email chain five times.

Clients usually tell me the same thing after the first clean comparison: “I finally understand why the quote changed.” Exactly. That’s the point. If you can compare packaging material cost per square inch with real specs and clear assumptions, you stop buying on instinct and start buying on numbers. That makes budget approvals easier and reorders less painful. It also makes your supplier calls shorter, which is a kindness everyone can appreciate.

And because people always ask for proof, yes, I still prefer factories that show me their scrap bins, their scoring tests, and their press setup sheets. If a converter can’t explain why a quoted board grade was chosen, I get suspicious. Fast. Experience teaches that a supplier who can walk you through yield, finish, and lead time usually ends up being cheaper than the one who only sends polished PDF quotes. The factory in Dongguan that showed me their score test sheet in under 30 seconds got the order. The one that sent me a glossy brochure and three emojis did not.

Next Steps to Compare Packaging Material Cost Per Square Inch

If you’re ready to move, here’s the cleanest path: measure the dieline, list the material spec, request matched quotes, and compare all-in pricing on the same basis. That’s how you compare packaging material cost per square inch without getting tricked by sheet size or surface polish. One spec sheet. One quote format. One decision rule. Simple, not easy. But it works better than hoping the cheapest-looking quote is actually the cheapest run.

Before you approve anything, compare at least three options. Keep the format consistent. Include material, print, finish, setup, scrap allowance, freight, and lead time. If one supplier is missing a line item, ask them to fill it in. Don’t let “not included” hide in the fine print. It always costs more later. I’ve seen a $0.08 per unit difference disappear once liftgate delivery and import duties were added for a shipment into California.

Request a sample or prototype before a full run, especially if the package has tight tolerances or premium finishes. A good sample tells you more than a polished quote. I’ve approved a project on paper and then rejected it in person because the fold memory was weak and the print sat too glossy for the brand tone. Packaging design is nice. Finished performance is what sells. If the sample takes 6 business days and the production slot is 14 business days after proof approval, that’s a timeline worth planning around, not guessing at.

Use this internal checklist before purchasing signs off:

• Flat dieline area confirmed
• Material grade and thickness confirmed
• Print coverage and finish confirmed
• MOQ and setup charges confirmed
• Scrap allowance disclosed
• Freight and delivery terms included
• Sample timing and production timing separated
• Artwork approval and revision limits set

If you’re comparing kraft paper against coated board or corrugated cardboard against rigid chipboard, remember the job is not to find the cheapest raw sheet. The job is to find the cheapest finished package that still protects the product, fits the brand, and ships without drama. That’s the real way to compare packaging material cost per square inch. And yes, I’ve seen a lot of people skip that last part and regret it on the reorder. One imported skincare line in Vancouver looked great on paper and lost $620 on damage claims because the mailer spec was too soft for cold-weather transit.

So keep the decision rule simple: use one spec sheet, one quote format, and one finish standard. Then compare packaging material cost per square inch on finished, usable area, not on wishful thinking. Do that, and your buying process gets cleaner, your budget gets tighter, and your supplier conversations get a lot shorter. Which, honestly, is one of the few joys left in packaging procurement. If the final quote is still fuzzy after that, the problem is probably not your math.