Size conversion does not work by adding a fixed number. The only reliable method is to compare garment measurements, not labels: an Asian L is typically one to two sizes smaller than a US L, an EU size number is a body measurement rather than a garment size, and a US letter size depends on the brand’s vanity sizing. For bulk orders, specify the measurement table in centimetres with tolerances, and plan the size ratio from your own workforce data.
Key takeaways
- Labels lie; measurements do not. Always compare chest, waist and length in centimetres.
- Asian sizing runs one to two sizes smaller than US letter sizing on the same garment.
- EU numbers are body measurements, not garment measurements, and they differ between men’s and women’s ranges.
- Trousers are sized by waist in inches (US) or centimetres (EU), which is more reliable than letter sizes.
- Always approve a size set — one garment per size — before bulk production.
1. Why size conversion goes wrong
There are three different things called “size”, and most conversion errors come from mixing them up.
| Type of size | What it describes | Example | Risk |
|---|---|---|---|
| Body size | The wearer’s measurements | Chest 102 cm, waist 91 cm | Varies enormously within one “size” |
| Garment size | The finished garment measured flat | Chest 62 cm flat, so 124 cm circumference | Includes ease, which differs by style |
| Label size | The letter or number printed on the label | L, XL, 52, 34 | Not standardised between brands or countries |
The practical rule: buy by garment measurement, plan by body size, and treat the label as a marketing convention. A workwear jacket needs 10–20 cm of ease over the wearer’s chest so it can be worn over a shirt or fleece; a T-shirt needs 6–10 cm. That difference alone explains why the same person wears two different label sizes in two different garments from the same brand.
2. The measurement points that matter
| Measurement | How to measure the wearer | How the factory measures the garment |
|---|---|---|
| Chest or bust | Around the fullest part, tape level, over a shirt | Flat across the chest 2.5 cm below the armhole, doubled |
| Waist | Around the natural waist, or where the trouser sits | Flat across the waistband, doubled |
| Hip or seat | Around the fullest part of the seat | Flat 20 cm below the waistband, doubled |
| Shoulder width | Shoulder point to shoulder point across the back | Seam to seam across the back |
| Sleeve length | Shoulder point to wrist, arm slightly bent | Shoulder seam to cuff edge |
| Inseam | Crotch to the required hem point | Inside leg seam, crotch to hem |
| Body length | High point of shoulder to the preferred hem | HPS to hem |
Note the last column carefully: a factory measures the garment flat and often reports half measurements. If a supplier quotes “chest 62 cm” for a large jacket, they usually mean 62 cm flat, which is 124 cm around. Confirming this single convention prevents a very expensive misunderstanding.
3. Men’s workwear: US, EU and Asian comparison
Chest measurements are body measurements in centimetres; the garment will be larger by the ease allowance.
| Label | US / UK letter | EU size | Body chest (cm) | Asian equivalent label |
|---|---|---|---|---|
| S | S | 44–46 | 86–91 | L or XL |
| M | M | 48–50 | 91–97 | XL or 2XL |
| L | L | 52–54 | 97–102 | 2XL or 3XL |
| XL | XL | 56–58 | 102–107 | 3XL or 4XL |
| 2XL | 2XL / XXL | 60–62 | 107–112 | 4XL or 5XL |
| 3XL | 3XL | 64–66 | 112–117 | 5XL or 6XL |
| 4XL | 4XL | 68–70 | 117–122 | 6XL or 7XL |
The Asian column is the point that causes the most trouble for buyers importing from China: a factory following the domestic Asian size curve will label a garment “XL” that corresponds to a US medium. Always confirm which size curve the factory is grading to, and require the letter size on the label to follow the destination market.
4. Women’s workwear sizes
| EU size | US size | UK size | Bust (cm) | Waist (cm) | Hip (cm) |
|---|---|---|---|---|---|
| 36 | 4 | 8 | 80–83 | 62–65 | 86–89 |
| 38 | 6 | 10 | 83–86 | 65–68 | 89–92 |
| 40 | 8 | 12 | 86–89 | 68–72 | 92–96 |
| 42 | 10 | 14 | 89–93 | 72–76 | 96–100 |
| 44 | 12 | 16 | 93–97 | 76–80 | 100–104 |
| 46 | 14 | 18 | 97–101 | 80–85 | 104–108 |
| 48 | 16 | 20 | 101–105 | 85–90 | 108–113 |
Women’s industrial workwear is not simply a smaller version of the men’s pattern. Shoulder width, sleeve length, waist position and hip allowance differ, and forcing a unisex chart on a mixed workforce produces returns and complaints. If 10–30% of your workforce needs a women’s fit, specify a separate size chart and stock line.
5. Trouser waist sizing: the most reliable dimension
| US waist (in) | EU size | Body waist (cm) | Notes |
|---|---|---|---|
| 30 | 44–46 | 76 | Common smallest stocked size |
| 32 | 46–48 | 81 | High-demand size |
| 34 | 48–50 | 86 | High-demand size |
| 36 | 50–52 | 91 | High-demand size |
| 38 | 52–54 | 97 | Frequently underestimated |
| 40 | 54–56 | 102 | Frequently underestimated |
| 42 | 56–58 | 107 | Stock a small buffer |
| 44 | 58–60 | 112 | Order on demand |
| 46+ | 60+ | 117+ | Order on demand |
Waist sizing is the one place where workwear is genuinely standardised, because it is measured in a real unit rather than a letter. Where a programme allows it, specify trousers by waist measurement and inseam length, and use letter sizes only for tops. It removes most of the ambiguity from bulk ordering.
6. Inseam and leg length
| Inseam (in) | Inseam (cm) | Typical wearer height | Stocking note |
|---|---|---|---|
| 28–29 | 71–74 | Under 168 cm | Low demand; order on request |
| 30–31 | 76–79 | 168–175 cm | Stock in moderate quantity |
| 32–33 | 81–84 | 175–183 cm | Highest demand; stock well |
| 34–35 | 86–89 | 183–190 cm | Frequently underestimated |
| 36+ | 91+ | Over 190 cm | Order on request |
7. Unisex, men’s and women’s fit compared
| Pattern area | Men’s | Women’s | Unisex |
|---|---|---|---|
| Shoulder | Wider, straighter | Narrower, more slope | Men’s proportions |
| Chest and bust | Straight side seams | Shaped with bust allowance | Straight, generous |
| Waist | Straight or slightly shaped | Shaped, higher position | Straight |
| Hip | Minimal allowance | Additional allowance | Minimal |
| Sleeve length and opening | Longer, wider cuff | Shorter, narrower cuff | Men’s lengths |
| Best used for | Predominantly male crews | Mixed crews with female staff | Uniform stock simplification |
8. Extended sizes and big-and-tall
| Size | Body chest (cm) | Body waist (cm) | Pattern adjustments required |
|---|---|---|---|
| 3XL | 112–117 | 107–112 | Deeper armhole, reinforced side seams |
| 4XL | 117–122 | 112–117 | Adjust shoulder slope, lengthen body |
| 5XL | 122–128 | 117–122 | Adjust front rise, add gusset where needed |
| Tall (L/XL with +5 cm sleeve and inseam) | As base size | As base size | Extend sleeve, inseam and body length |
Extended sizes should not be a scaled-up copy of the base pattern. Grading alone distorts armholes, necklines and rises, so specify which points are adjusted and approve a sample in the largest stocked size, not only in L.
9. Size sets: the cheapest insurance in bulk ordering
A size set is one garment per size, produced before bulk. It costs very little and catches grading errors that would otherwise appear across thousands of pieces.
| Size set stage | What it proves | Cost implication |
|---|---|---|
| Fit sample in base size | Fit and pattern are correct | One garment |
| Size set S to 3XL | Grading works across the range | Six to eight garments |
| Wear trial with the client | Comfort in real working conditions | Ten to twenty garments |
| Pre-production approval | Bulk matches the approved specification | One approved sample, retained and signed |
10. Building your own size chart
- Choose the base size, normally L for workwear.
- Measure five to ten wearers who correspond to that base size within the actual workforce.
- Record body measurements, then add the correct ease for each garment type: 6–10 cm for T-shirts, 10–20 cm for jackets, 4–8 cm for trousers.
- Set the finished garment measurements with tolerances, typically ±1.0 cm on the chest and ±0.5 cm on the shoulder.
- Define the grade increments between sizes, usually 4–5 cm on the chest and 4 cm on the waist.
- Add the destination market’s letter size to each row so the label matches buyer expectations.
- Test the chart with a size set before committing to bulk.
- Publish the chart as part of the product data, in both centimetres and inches.
- Review the chart annually against returns, exchanges and wearer feedback.
- Keep the version number, approval date and approver name on the document.
11. Collecting measurement data from your workforce
| Method | Speed | Reliability | When to use it |
|---|---|---|---|
| Self-reported sizes | Fast | Low | Never for a first order |
| Existing uniform sizes | Fast | Medium | Useful if the previous supplier’s fit is known |
| Measuring a sample of the workforce | Medium | High | The best compromise; measure 10–15% of staff |
| Professional measuring session | Slow | Highest | Large programmes and high-value garments |
| Size set trial with feedback forms | Medium | High | New styles and new factories |
12. Tolerances and acceptance
| Measurement | Typical tolerance | Acceptance note |
|---|---|---|
| Chest, waist, hip | ±1.0 cm | Recorded on the tech pack |
| Shoulder width | ±0.5 cm | Shoulder is highly visible and should be tight |
| Sleeve, inseam, body length | ±0.8 cm | Longer deviations affect fit noticeably |
| Neck opening | ±0.5 cm | Affects comfort and appearance |
| Elasticated waist, relaxed | ±1.5 cm | Wider tolerance because of elastic behaviour |
A garment outside the agreed tolerance is a defect, regardless of whether your own wearer happens to find it comfortable. Tolerances exist so that the acceptance decision is automatic rather than a matter of opinion.
13. Common mistakes
- Converting sizes by adding a fixed number of sizes for an Asian supplier.
- Assuming half measurements are full measurements, or the reverse.
- Forgetting ease: a body chest of 102 cm does not require a 102 cm garment.
- Using a unisex chart for a workforce that needs women’s fit as well.
- Skipping the size set and discovering the error in the bulk delivery.
- Failing to state tolerances, so a garment that does not fit cannot be rejected.
14. Frequently asked questions
Is Asian sizing smaller than US sizing?
Yes. An Asian L usually corresponds to a US M or S in the same garment type, and the difference can reach two sizes. The reliable comparison is the garment’s chest, waist and length measurements in centimetres, not the letter on the label.
How do I convert EU sizes to US sizes for workwear?
Treat the EU number as a body measurement rather than a garment size: EU 50 for men is close to a US medium, EU 54 to a US large. Confirm against the garment’s chest measurement rather than relying on the conversion alone.
What size should I order for a mixed workforce?
Plan from your own data. In industrial settings, demand typically concentrates at L, XL and 2XL, with 10–15% at 3XL and above. If 10–30% of staff need a women’s fit, specify a separate women’s chart and stock line.
How much ease should a workwear garment have?
Around 6–10 cm of chest ease for a T-shirt or polo, 10–20 cm for a jacket worn over layers, and 4–8 cm at the waist for trousers. Garments designed for over-garment use need more.
What is a size set and do I need one?
A size set is one garment per size produced before bulk. It costs a handful of garments and proves the grading works, catching errors that would otherwise be repeated across the whole order.
How many wearers should I measure?
Measuring 10–15% of the workforce gives a reliable picture. Self-reported sizes are notoriously inaccurate and should never be the basis for a first bulk order.
Why does the same person wear different sizes in different garments?
Because ease differs between garment types. A person may wear medium in a T-shirt and large in a jacket that is cut for wearing over a shirt or fleece. That is normal, not a sizing inconsistency.
Should the label letter match the Asian size or the destination market?
It should match the destination market. Ask the factory to keep its internal sizing but print the letter size and measurement table your buyers expect, because a mislabelled garment creates returns even when the fit is correct.
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