Sizing is where most OEM orders go wrong — the sample fits, the bulk does not. This guide covers the 5 main size systems used globally, how to specify fit in your tech pack, how grading works (and why it is the silent failure point for many first orders), and the 3 most common sizing mistakes that lead to bulk-level rejections.

Why sizing is the #1 source of OEM quality issues

  • The most common reason for bulk-level rejection (more than fabric, more than decoration)
  • Sample fits perfectly, bulk pieces do not — the factory drifted across the run
  • Each market has different size conventions (S in the US is not S in China)
  • Grading is mathematically complex and rarely tested properly before bulk

The 5 main size systems used globally

1. US / North America

  • Letter sizes: S, M, L, XL, XXL (tops, dresses)
  • Numeric for pants: 28-44 (waist in inches), inseam 28-36
  • Body measurements: chest, waist, hips, inseam, sleeve
  • ASTM D6240 (general), D5586 (mature men), D6456 (women misses), D6027 (children)
  • Plus sizes 1X-5X use a different block (not just graded up)

2. EU / UK

  • Numeric: 36-58 (chest for men, bust for women)
  • Different countries may have small differences in interpretation
  • EN 13402 standard for body measurements

3. Asia (China, Japan, Korea)

  • Smaller frames on average than US or EU
  • Letter sizes S-M-L used but with smaller body measurements (often 4-6 cm smaller than US)
  • Japan often uses numeric (S = 36, M = 38)
  • China uses standard letter but with Asian body proportions
  • Korea uses both systems

4. Mexico / Latin America

  • Alpha (CH/MD/G/XG) and numeric (28-38)
  • Typically 2-3 cm smaller than US per measurement
  • Often slim-fit preference

5. Custom (narrow markets)

  • Brand-specific size charts (e.g. Allbirds, Warby Parker)
  • Petites, tall, big & tall
  • Plus-size blocks (1X-5X) — different pattern, not just graded
  • Custom fit programs (Nike ID, Adidas miadidas — co-creator with brand)

How to pick the right size system for your market

  • US-only buyers: US sizes (S/M/L for tops, waist x inseam for pants)
  • EU + UK buyers: EU numeric (36-58)
  • Japan or Korea buyers: their numeric or Asian-letter chart
  • Global e-commerce: provide chart in cm + convert to inches; let customer pick
  • Multi-market brands: maintain separate charts per market, not one chart

Fit types: regular vs slim vs relaxed vs oversized

Regular fit

  • Standard body-shape accommodation
  • Loose enough for movement, not baggy
  • Default for most mass-market brands

Slim fit

  • Narrower through chest, waist, and sleeves
  • Closer to body silhouette
  • Common in European fashion, especially suiting

Relaxed fit

  • Wider through body and sleeves
  • Loose for comfort
  • Common in casual and streetwear

Oversized / Boxy

  • Significantly larger than body
  • Intentional drape
  • Strong in streetwear since 2018

Athletic fit

  • Tapered at waist, broader at chest and shoulders
  • For muscular builds
  • More common in the US

Spec sheet anatomy

Point of measure (POM) table

  • For each POM: name, measurement per size, tolerance
  • Typical POMs for tops: chest, body length, sleeve length, shoulder width, hem, armhole, neck width
  • Typical POMs for bottoms: waist, hips, inseam, outseam, front rise, back rise, leg opening, thigh

Reference image or sketch

  • Show where each POM is taken on the garment
  • Especially important for unusual measurements (e.g. “2 cm below armhole”)

Tolerance per POM

  • Tighter tolerance (±0.5 cm) for fitted garments
  • Looser tolerance (±1.0 cm) for relaxed / oversized garments
  • Industry standards: ±0.5 cm for adult knits, ±1.0 cm for adult wovens, ±0.3 cm for children’s

Grading specs

  • How sizes differ from S to M to L (the “ruler” of the pattern)
  • Example: chest +5 cm, length +2 cm, sleeve +1 cm per size
  • Grading rules depend on size system and fit type

How to specify sizing in your tech pack

For each garment, your tech pack should specify:

  1. State the size system (US letter, EU numeric, Asia, etc.)
  2. Provide the size run (e.g. S, M, L, XL or 28, 30, 32, 34 or 36, 38, 40)
  3. Provide the size chart with measurements per size (cm or inches)
  4. Specify fit type (regular, slim, relaxed, etc.)
  5. Specify tolerance per POM
  6. Specify grading rules (if not standard)
  7. Provide a reference image showing where each POM is taken

For full guidance on tech pack structure, see our complete tech pack guide.

Common sizing mistakes that lead to bulk rejection

1. Sampling without proper measurement

Sample looks fine, but the sample measurements are not measured against your spec. Always measure the sample at every POM and compare to your spec sheet — visual fit impression is not enough.

2. Trusting the factory’s “stock” size chart

The factory stock size chart is generic, not your spec. Even if it covers the same size run, measurements may differ by 0.5-1.5 cm. Always provide your chart, even if it looks “the same”.

3. Specifying tolerance too loose

Default factory tolerance is ±1.0 cm; you wanted ±0.5 cm. Order “spec” without explicit tolerance means factory defaults to the looser tolerance, which can add up to 2 cm of total drift across the size run.

4. Specifying POM without reference image

“Chest” can be measured at different points (under armhole, 2 cm below armhole, across the body, etc.). Without a reference image, factory measures their way, not yours.

5. Skipping size set samples

For size runs >3 sizes, request a size set sample (one of each size). Without it, the factory may not realize a grading issue until bulk — when it is too late.

6. Using size labels alone (S/M/L) without specifying the size chart

Different markets use different conventions for the same letter. “M” in the US, EU, and Asia are 3 different sizes. Always provide the actual measurement chart, not just the size labels.

7. Specifying fit type without a reference garment

“Slim fit” is subjective. One factory’s “slim” is another factory’s “regular”. Provide a reference garment (image plus key measurements) for each fit type to remove ambiguity.

How grading works (and why it matters)

Grading is the mathematical process of scaling up or down from a base size (usually M) to all other sizes in the run. The factory starts with the base size pattern and applies grading rules (e.g. “chest +5 cm per size, length +2 cm per size”) to create the other size patterns.

Industry-standard grading rules

  • Men: chest +5 cm per size, length +2 cm per size
  • Women: bust +4 cm, waist +4 cm, hip +4 cm per size
  • Children: depends on age range, typically +4-6 cm chest per size
  • Plus sizes (1X-5X): different block, not just graded up

Common grading problems

  • Wrong starting size (factory starts at L instead of M)
  • Missed POM (factory grades chest but forgets shoulder width)
  • Asymmetric grading (factory adds 5 cm to one side instead of 5 cm total)
  • Wrong reference point (factory grades from seam instead of body point)

How to handle plus sizes (1X-5X)

Plus sizes are a different block, not just a graded extension of misses sizes:

  • Body proportions change — longer torso, fuller bust, different armhole depth, fuller hip
  • The pattern must be redesigned for the plus-size block
  • Grading rules may not extrapolate linearly from misses sizes

Always ask the factory if they have a plus-size block before bulk. If they grade plus sizes from misses sizes, expect fitting issues — and budget for the rework.

Market-specific tips

US buyers

  • ASTM standards for general population
  • 1X-5X for plus (use a separate block, not a graded extension)
  • Numeric (waist x inseam) for pants
  • “True to size” matters — returns are costly (typically 15-30% of revenue is return-related for off-size items)

EU buyers

  • EN 13402 numeric (36-58)
  • Often slim fit preference, especially in suiting and fashion
  • Smaller frame than US by 2-4 cm per measurement

Asian buyers

  • Smaller frame, but current trend is toward oversized / relaxed
  • Japan often uses numeric (S = 36 etc.)
  • Korea similar to Japan, with growing preference for Western fits

Latin America

  • Alpha (CH/MD/G/XG) and numeric (28-38)
  • Often slim-fit preference (especially for women’s apparel)

Global e-commerce

  • Provide size chart in cm + convert to inches
  • Show chart on the product page (reduces returns 5-15%)
  • Compare your size to a major brand (e.g. “fits like Nike size M”) — this is helpful for shoppers

FAQ

How do I write a size chart if I have no reference garment?

Start with your target market’s standard size chart (ASTM for US, EN for EU). Request a size set sample to verify the fit. Iterate 1-2 times based on fit feedback. A generic standard is a reasonable starting point for most products.

What is the difference between “size” and “fit”?

Size = the body measurements the garment is intended to fit. Fit = how the garment sits on the body (slim, regular, relaxed, oversized). Same size can have different fits — e.g. “size M regular fit” vs. “size M slim fit”. Specify both in your tech pack.

Can I use the factory’s stock size chart?

Only if their chart exactly matches your spec to the cm. Most factories have stock charts per size system but measurements may differ by 0.5-1.5 cm. Always provide your chart, even if it visually looks “the same”.

What is “size grading” vs “size scaling”?

In apparel context, both mean the same thing — the mathematical process of scaling a pattern from one size to all sizes in the run. “Grading” is the industry-specific term.

How long does grading take?

  • New style with new size chart: 3-5 days for grading rules + 5-7 days for sample
  • Existing style with existing grading: 1-2 days for a new size sample

What if my size run has gaps?

Some brands skip sizes (S, M, L only — no XS or XL). This is common for premium brands focusing on a core size range and reduces inventory complexity. Just be explicit in your tech pack: “size run is S, M, L only”.

Can I order one size at a time?

Single-size orders are usually above factory MOQ (the factory needs to set up the production line once for the size run). Some factories accept single-size orders if you commit to repeat orders across the size run. Others prefer split-fulfillment: start with core sizes, add more sizes in repeat orders.

Should size labels match the size chart?

Yes — if your chart says M = 41 cm chest, your size label says M. Off-the-shelf size labels (S, M, L with no measured definition) do not help the consumer. Either specify exact measurements per size on the label, or provide a clear chart on your product page.

What is “vanity sizing” and how does it affect me?

Vanity sizing is when brands label garments smaller than the actual measurement (a “M” labeled garment fits a L body). Common in US mass-market apparel. If you sell in the US market, be aware — your size chart may need to be larger than ASTM standard if you want to feel competitive.

How this fits the buyer journey

Sizing comes up at every step:

How we work at Kemondo

At Kemondo Apparel, we have standard size charts for US, EU, and Asia markets per product type. For first orders, we recommend starting with our standard chart plus your fit direction (slim, regular, relaxed, oversized). We send a size set sample (one of each size in the run) for your written approval before bulk. Our grading rules are ASTM-based for US orders and EN-based for EU orders. Tolerance defaults to ±0.5 cm for adult knits, ±1.0 cm for adult wovens, ±0.3 cm for children’s. For plus-size orders, we use a separate plus-size block, not a graded extension.

Have sizing questions for your next order? Message us on WhatsApp. We usually reply within 12 hours with size chart templates and fit guidance for your target market.