Activewear Size Charts: How to Read Them and Convert US, UK, EU and AU Sizes
Short answer: First check whether a chart lists body measurements (the body the size is made to fit) or garment measurements (the garment laid flat), and whether it is in inches or centimetres. Then measure the points requested by that product's chart: a leggings chart may use waist, hips, inside leg or a combination; other garments may require bust, underbust, chest or waist. Match those measurements to the brand's own chart. National label conversions are examples from particular brands, not a universal rule.
Body measurements or garment measurements?
ISO 8559-2:2025 describes a size-designation system based on body measurements. A seller may also publish the finished garment's dimensions, sometimes measured flat. Check which type of chart you are reading before you choose a size.
| Chart shows | The numbers describe | How to use it |
|---|---|---|
| Body measurements | The body the size is made to fit | Measure yourself and find your range |
| Garment measurements | The garment, often laid flat (half the circumference) | Compare with a garment you own and like |
Stretch garments add a twist. A particular legging, sports bra or compression top may use negative ease, so a waistband that measures small flat is not automatically the wrong size; check that product's intended fit and measurements in how tight training apparel should be. Check the chart's unit as well; brands in any market may publish inches, centimetres or both.
How to measure for activewear
Measure over the underwear you will wear with the garment, with a soft tape held level and snug, not tight.
| Measurement | Where | Common sizing input (confirm the brand's chart) |
|---|---|---|
| Bust | Fullest part of the bust | Women's tops, jackets and dresses |
| Underbust | Directly under the bust | Bras, together with bust girth |
| Chest | Around the chest, under the arms | Men's tops and jackets |
| Waist | Natural waist | Men's trousers and shorts |
| Hips | Fullest part of the seat | Women's trousers, shorts, leggings and skirts |
| Height, inside leg | Standing, without shoes | May be primary or secondary inputs, depending on the product chart |
Letter sizes and numeric sizes
Letter sizes (XS to XXL) are ranges each brand defines for itself. Numeric labels also vary by brand and market. The chart that decides your size is the one published for the actual garment you are buying, preferably with body measurements rather than label numbers alone.
Women's sizes: one retailer's conversion example
| US | UK | AU | EU | IT |
|---|---|---|---|---|
| 2 | 6 | 6 | 34 | 38 |
| 4 | 8 | 8 | 36 | 40 |
| 6 | 10 | 10 | 38 | 42 |
| 8 | 12 | 12 | 40 | 44 |
| 10 | 14 | 14 | 42 | 46 |
| 12 | 16 | 16 | 44 | 48 |
| 14 | 18 | 18 | 46 | 50 |
| 16 | 20 | 20 | 48 | 52 |
Example: ASOS's own women's jeans, trousers and leggings conversion chart. It says other brands may vary. These numbers describe ASOS labels, not a rule for every US, UK, Australian, European or Italian garment. Compare the brand's body measurements before ordering.
An "EU" label does not tell you which brand chart or garment measurements were used. Ask for the underlying body measurements when the chart is unclear.
- Australia: ASOS maps its AU 10 to UK 10 and US 6, but another brand may use a different chart. Compare body measurements in the units shown on that brand's chart.
- Canada: there is no mandatory system. The Competition Bureau states that the Textile Labelling Act does not require garments to conform to specific size dimensions or size codes, but that a stated dimension such as "size 36 waist" must be accurate and not false or misleading.
- United States: numeric garment sizes are not a universal conversion. Compare the seller's own body measurements and intended fit; a standards table is not a substitute for the chart of the garment you are buying.
Men's sizes
For men's tops, compare chest girth with the chart for that specific garment; for trousers and shorts, compare waist girth. Do not convert a sports-shirt letter size into a jacket number: those are different product charts, not equivalent measurements.
Sports bra sizes
A bra chart may use underbust and bust measurements, while another uses letter sizes. Measure both girths and read the brand's own chart rather than converting a letter to a cup without its measurements. For the brand side of this, see private-label sports bra development.
Reading Chinese size codes
China's GB/T 1335 provides a size-designation system. Its women's part, GB/T 1335.2-2008, was confirmed as still valid at its review on 30 May 2025. That record does not show how often brands adopt it. In a code such as 160/84A, the Suzhou market regulator explains that the first figure is height in centimetres and the second a body girth in centimetres, followed by a figure-type letter. Check the product's own chart to learn which girth and fit it uses.
What the evidence supports:
- A letter alone is not a conversion. GB/T 1335 uses height and girth in centimetres. A seller's S, M or L needs that seller's actual body or garment measurements before it can be compared with another label.
- Listings may quote flat garment measurements, which look smaller than body measurements for the same size.
Where a garment is sewn does not decide its sizing: one made in China for a US or UK brand can be cut to that brand's chart. For a code such as 160/84A, check what the second number measures for that garment and compare it with your own measurement.
How we build a brand's size chart at the factory
A brand's body chart and its garment chart answer different questions. Before grading, agree on the base size, the intended fit and the measurement increments across sizes — see size grading for activewear and petite, tall and curvy grading. For stretch styles, specify the garment measurements and tolerances against the approved sample rather than assuming the label determines compression. Agree which points of measure are checked at inspection; our finished-goods inspection uses AQL 2.5 in house. For seamless styles, confirm the proposed size range against the actual design and machine setup; cylinder diameter alone does not establish a universal finished size range.
What to publish on your own size chart
Body measurements as ranges in centimetres, with inches added for US shoppers; any garment measurements labelled separately, so nobody reads a flat waist as a body waist; how the style is meant to fit, in one word — compression, standard or relaxed; and size codes that match the measurements behind them, since shifting a code away from its measurements only passes the confusion to your customer.
What we do at YOUMEGA
We make activewear in two facilities: cut-and-sew and quality control at our Xiamen headquarters, and seamless knitting in Yiwu. Stock styles with your logo start from 100 sets, with mixed colours and sizes allowed, which is a practical way to test a size curve before committing; our first order calculator helps plan the split. The fully custom OEM/ODM minimum is 300–500 pieces per style per colour, depending on the product. Fit is settled in sampling: an OEM development sample takes 10–15 days; an ODM development sample takes about 7–10 days, not counting design preparation.
FAQ
How do I read a size chart? Check whether it lists body measurements or garment measurements, and whether it uses inches or centimetres. Measure the points that the actual product chart requests; leggings may call for waist, hips, inside leg or more than one of these. Compare every required measurement with its range, then check the intended fit if sizes overlap.
Is a size chart in inches or centimetres? Either, depending on the brand and the particular chart. Check the header, convert your own measurements into its unit rather than converting the whole chart, and prefer charts that print both units.
How do UK sizes convert to US and EU sizes? There is no universal conversion. In ASOS's own women's leggings chart, UK 10 aligns with US 6, EU 38, IT 42 and AU 10. Check the brand's measurements in centimetres before ordering; another brand can label the same fit differently.
What size chart does Australia use? Labels vary by brand. ASOS maps its AU 10 to UK 10 and US 6, but this is one retailer's conversion. Use the actual seller's body measurements in the units stated on its chart.
What size chart does Canada use? None is mandatory. The Competition Bureau states that the Textile Labelling Act does not require garments to conform to specific size dimensions or size codes, but that any dimension given, such as a waist size, must be accurate and not misleading. Check whether a Canadian chart uses US-style numbers or centimetres.
Why can Chinese-market sizes differ from another brand's? There is no universal S/M/L conversion. A code such as 160/84A expresses height and a body girth in centimetres under a Chinese designation system; the seller's chart must identify the relevant girth and fit. Compare measurements, not letters or country labels.
Why do sizes differ between brands? Brands choose different body ranges, fit models and garment allowances for a label. ISO 8559-2:2025 establishes a body-measurement approach to size designation, while retailer conversion charts may still differ. Read the measurements behind each brand's label.
Can I choose a size by weight or age? Not reliably for adult activewear. Compare the body measurements requested by the garment's chart; two people of the same weight or age can need different garment measurements.
Building a size chart for your first range? Tell us your market and the size range you want, and we will tell you which measurements we would fix first, and why.
Sources
- ISO 8559-2:2025, Size designation of clothes — Part 2: Primary and secondary dimension indicators (official summary)
- ASOS, Women's Jeans & Trousers Size Guide, own-brand international conversion table
- Standardization Administration of China, record for GB/T 1335.2-2008, Standard sizing systems for garments — Women
- Suzhou Municipal Market Supervision Administration, guide to garment size designation
- Competition Bureau Canada, Textile labelling requirements
