Apparel Size Chart & Grading: OEM Fit Guide
Apparel Size Chart & Grading: OEM Fit Guide
Last year a European yoga brand walked in with a pile of returned garments. The factory before us — a peer shop — had run 2,000 pieces, and the bulk XL came back too tight. At the sealed-sample stage the M had been signed off by both sides with no argument. Then bulk XL measured 1.5cm smaller at the chest than the sealed sample.
We helped them trace it, and the answer wasn't that the other factory sewed it wrong. The tech pack only carried one size — the M — with no grade rule. That factory graded by its own default, so its XL came out tight, while the brand's mental picture of an XL was a different set of numbers entirely.
Here's the uncomfortable truth we've learned running two facilities in Dongguan since 2014: most "the bulk sizing is wrong" complaints don't start on the sewing floor. They start because the size chart never stated how much each adjacent size is supposed to differ. Buyers send a base size, not grade increments. They send fabric composition, not how a stretch fabric should be shrunk. So the factory defaults — and the result isn't the size run in your head.
This guide is written for brand sourcing managers, product developers, and founders. We're a sportswear factory supplier doing OEM and ODM work, and the six-part checklist below comes from fixing the same mistakes across 1,200+ brand orders — not from a textbook.
The Five Mistakes Buyers Make on Size Charts and Grading
- Base size only, no grade rule. The chart lists an M and leaves L, XL, XXL to the factory's default. Your M in another system is someone else's L, and the whole size run drifts.
- Stretch fabric graded with woven logic. Many brands grade a base layer like woven cloth — chest +4cm per size. But 4-way stretch recovers, so graded that way the XL comes out too tight to wear. We've seen this too many times.
- One flat tolerance. Twelve points of measure each at ±1cm. Worst case, two adjacent sizes land 2cm apart at some points. Flat tolerance just stacks.
- Mixed market systems. The same "M" in US, EU, UK, and Asian charts can differ 4–6cm at the chest. The pack doesn't say which system, and bulk on the shelf gets "wrong size" complaints.
- Skipping the fit sample. Seal one base size and go straight to bulk, and you lose the only pre-bulk checkpoint. Every other size in the run is never worn or tested before it ships.
What a Workable Size Chart + Grading Spec Contains
A spec that walks into our cutting room ready to grade has six blocks. Miss any one and size-run consistency rides on luck.
1. Set the base size
Use your best-selling size as the master, the base size. Don't pick the smallest or the largest. The closer the base is to your volume size, the more accurate the whole run — grading only adds and subtracts from the base, so the base has to be right first. We default to men's M and women's S/M as the base.
2. Define the POM (point of measure)
Every measurement must state where it's taken: chest measured how many centimeters below the armhole, body length from center-back neck to hem, sleeve from shoulder point to where. Same garment, a 2cm slip in the measuring point, and the reading moves half a size. Without POM, our floor and your QC never agree on the number.
3. Give the grade rule
This is the most common omission. State how much each point changes per adjacent size. The industry woven men's baseline runs chest +4cm per size, body length +2cm, sleeve +1.5cm. But knit and stretch fabric halve that or less — for 4-way stretch we recommend starting the chest at +2cm per size, or the larger sizes tighten as they grade out. No grade rule means leaving "what your XL looks like" to the factory's guess.
4. Grade the tolerance
Don't write ±1cm everywhere. We recommend keeping key structural points — chest, body length, sleeve — within ±1.0cm, and relaxing stretch and elastic points like waistband, cuff, and neckline to ±1.5cm. Graded tolerance holds the fit without flagging reasonable elastic variance as defects.
5. Gate with a fit sample
Before bulk, produce at least S, M, L, and XL each for a fit sample — not just one sealed base size. A real body or dress form wears them, and the off-size points in the run surface. This is the only pre-bulk checkpoint for sizing. Skip it and off-size only shows up through complaints.
6. Align the market system
State clearly which system the chart uses — US, EU, UK, or Asian — and attach a cross-system reference so end consumers don't feel the sizes run off. For multi-market sales we recommend one master system with a conversion appendix.
How we take your size pack from here
- Package screen. You send what you have — even a base size and scattered notes. Within 48 hours we return a grading gap list.
- Complete the spec. As your OEM/ODM partner we fill the missing grade rule, POM, graded tolerance, and market system into a gradable version.
- Fit sample. We produce the full size set for fit; both sides confirm before we seal the sample and run bulk.
- Produce and inspect. Full run at AQL 1.5 with our 8-step check, graded against the sealed sample and graded tolerance, shipped FOB Shenzhen.
Complete vs. Incomplete: What It Costs You
| Factor | Chart + grade rule complete | Base size only, no grade rule |
|---|---|---|
| Size-run consistency | stable, grade-rule based | every size on factory default, drifts |
| Off-size complaints | under 5% | often over 30% |
| Cross-size rework | rare | large and small sizes reworked repeatedly |
| Communication rounds | 2–3 | 6–8 and up |
| Hidden cost | low | returns, redo, trust — all lost |
Questions Buyers Actually Ask
Our size chart only has a base size. Can you grade it?
Yes. Filling that gap is exactly what an OEM/ODM partner is for. Send the base size and the category — woven, knit, or stretch — and within 48 hours we return a grade rule proposal: per-size, per-point increments plus a graded tolerance. You confirm, we grade. We don't believe in "send one M and we'll guess the rest."
How do I size stretch and knit so it doesn't run off?
Halve the grade increment. For 4-way stretch we recommend starting the chest at +2cm per size, while woven men's often runs +4cm. Also relax the tolerance to ±1.5cm on stretch points, or the fabric's natural recovery gets flagged as a defect. We keep a library of 200+ fabrics in Dongguan and can measure the recovery on your chosen fabric before we set the grade.
How much tolerance is reasonable?
Key structural points — chest, body length, sleeve — within ±1.0cm. Elastic points — waistband, cuff, neckline — at ±1.5cm. Don't write one flat ±1cm: twelve points all at ±1cm can leave two adjacent sizes 2cm apart at worst, manufacturing false defects. Graded tolerance protects both the fit and the yield.
Do I have to do a fit sample, and how long?
Strongly recommended, and at least S, M, L, XL each. With a complete pack, the full fit sample sits inside the 7–10 day sampling window. Skip it and you leave size-run risk to bulk and complaints — which costs ten times what sampling does.
How do US, EU, and UK sizing differences get handled?
The pack must name its system and carry a cross-system reference. Of the 1,200+ brands we've worked with, the multi-market ones pick one master system with a conversion appendix, which avoids end-consumer "wrong size" feedback. Lock it before sealing — changing systems at bulk is expensive.
Does the size-run width affect MOQ and price?
It does. Our standard MOQ 300 is a total-piece threshold, but a wider run — five sizes versus three — thins the per-size volume, and setup and marker amortization push the unit price up. We suggest new brands test with three sizes and expand once the style proves out, rather than opening seven sizes on day one.
What does FOB Shenzhen mean — does it include freight?
FOB Shenzhen means free on board at Shenzhen port. We move goods from Dongguan to Shenzhen, clear export customs, and load onto the vessel — everything up to that point is on us. Ocean freight and insurance from Shenzhen to your destination port are your side, or your freight forwarder's. The quote states the split plainly. No fog.
Send Us What You Have
Send your size chart — even if it's only a base size — or your inspiration images. Within 48 hours we return a grading gap list and help you complete the grade rule, POM, graded tolerance, and fit sample plan. Get the base right and the grade written, and you'll hold the first fit sample in 7–10 days.
As a sportswear manufacturer operating in Dongguan since 2014, we'd rather be a long-term partner than a one-order shop. Anything about sizing and grading you're unsure of, ask. We'll tell you straight. To see our OEM basics first, visit our OEM capacity page.
