Underwear Size Conversion Chart (EU / US / UK)

Sizing is where private-label programmes lose the most time: the same “M” means different measurements in the EU, the US and the UK, and childrenswear sizes are usually height-based. Use this table to align your grading before you send a tech pack. Based in Xiamen, Fujian Province, in the Xiamen–Quanzhou–Jinjiang knitwear cluster of south-east China, Unitex manages sampling, quality control and export documentation for every order.

Size conversion

How to use these tables

• Always grade from body measurements, not from another brand’s labels. The EU/US/UK mapping below is the common commercial convention — your buyer’s grade sheet wins where it differs.
• Waist bands stretch. Quote both relaxed and stretched waist; a tolerance of ±1 cm on the relaxed measurement is normal.
• Kids’ sizes are height-driven (80–130 cm), not age-driven. Age labels are marketing, height is production.
• US vs UK: US women’s sizes run two numbers below UK (US 8 = UK 12); men’s waist sizes are usually inches in both.

Send us your grade sheet or a reference garment and we will return a size-set sample in your target system before bulk production.

Which measurements does an underwear size actually describe?

A size label is a shorthand for four body measurements, and underwear is the garment where the shorthand fails most often, because the product sits at the hip rather than at the waist. The four that decide fit are:

• Waist, relaxed and stretched. Quote both. A relaxed waist alone tells you nothing about whether the elastic will hold, and a stretched figure alone tells you nothing about comfort at rest.
• Hip at the widest point. For briefs and boxer briefs this is the governing measurement, not the waistband. Two styles labelled the same waist size can differ by several centimetres at the hip.
• Front rise. The distance from the waistband to the crotch seam at the front. Rise decides whether a style sits at the natural waist or below it, and it is the measurement most often missing from a converted table.
• Leg opening. The circumference where the leg hem sits. Too tight and the style rides up; too loose and it gaps under trousers. It scales with thigh, not with waist.

Grade from body measurements, then derive garment measurements. Doing it the other way round — scaling a garment table by a fixed increment — is what produces a range that fits in the middle and fails at both ends, which is the single most common sizing complaint in private label programmes.

The tolerance column is industry practice, not a legal requirement: treat the figures as starting points for cotton-rich knits after one wash at 40 °C, confirm them against the fabric’s own shrinkage result to ISO 6330 and ISO 5077, and widen them where the fabric moves more. What matters is that the tolerance is written into the tech pack, because a measurement without a tolerance cannot be rejected at inspection. Measure at least three garments per size from the pre-production sample and three per size from bulk, record each point once flat, and treat any point outside the stated tolerance as a defect unless the tech pack names it as a critical or a minor dimension.

Why does the same letter mean different things in the EU, the US and the UK?

Because the three systems do not describe the same thing. The European system designates body dimensions in centimetres, so a size refers to the wearer. The US system for men’s underwear uses waist measurements in inches, and for women uses dress sizes that have drifted upward over decades through vanity sizing. The UK uses its own numeric scale for women, offset from the US by roughly four numbers: US 8 corresponds to UK 12, not UK 8.

The practical consequence is that converting a table by relabelling is the wrong operation. Converting changes what the size is called; it does not change the body the garment was graded for. A programme that takes a US grade sheet, relabels it in EU sizes and sends it to production will produce garments that fit the original US body, in packaging that claims otherwise.

What works instead is to state the body measurement range for each size in the destination market’s own convention, and let the labels follow. For a men’s programme that means a waist range in centimetres or inches per size; for women, hip and waist together, because dress size alone does not fix either; for children, height in centimetres.

How do you validate a converted table before cutting?

1. Pick the two extremes, not the middle. Cut the smallest and the largest size in the range first. A table that is wrong in the middle is usually wrong everywhere; a table that is wrong at the ends is wrong only where the volume is lowest and the returns are highest.
2. Fit on a body, not on a table. Wear-test both extremes for a working day, including sitting and walking. Seat coverage and leg ride-up do not show up on a flat measurement sheet.
3. Check the trims at the ends of the range. Waistband width, elastic stretch ratio, label size and gusset panel are usually specified for the middle of the range and become wrong at the extremes.
4. Lock the approved table in writing. Record body measurements, garment measurements and tolerances, and attach it to the purchase order. A second order can only reproduce a table that was written down.

For a first programme, expect to spend one sample round on this and treat it as the cheapest round you will ever run. The same discipline that fixes sizing also fixes repeatability: a table that is measured and recorded is a table a second order can hit, which is the same logic that governs lot control on the order size and batch consistency page.

What changes for children’s sizes?

Children’s sizing is height-driven, not age-driven. A 110 cm height corresponds to roughly four years in the European convention, but the correspondence between height and age varies enough between populations that age labels are marketing rather than production data. Specify height in centimetres, and specify the size ratio across the range, because the ratio determines how many cutting lays the order needs and therefore what quantity is economic.

Two regulatory points attach to children’s sizing and are worth fixing at the same time. Children’s underwear is tested to 16 CFR 1610; the sleepwear standards at 16 CFR 1615 and 1616 apply by size only to sleepwear, sizes 0 to 6X and 7 to 14 respectively; and 16 CFR 1501 applies to components on garments intended for children under three. None of the three is a sizing decision, but all are triggered by the size range you choose.

Where do these conventions come from?

The measurement side is standardised even though the conversion is not. ISO 8559-1 defines the anthropometric body measurements used to designate garment sizes, and EN 13402-3 sets out how sizes are labelled from body measurements and intervals. Neither standard supplies a table that converts one market’s size into another’s, which is why every EU, US and UK mapping is a commercial convention rather than a published equivalence; the table on this page is a starting point, not an authority.

What the standards do give you is a defensible basis for a conversation. If a supplier claims a measurement is correct, the question is which body measurement it corresponds to under ISO 8559-1, and what interval the size covers under EN 13402-3. Tolerances then become an inspection matter: they are verified at pre-shipment inspection, where ISO 2859-1 governs the sampling plan and the accept-or-reject decision, so a tolerance that is not written into the tech pack cannot be rejected against.

Last updated: 2026-11-09 · Xiamen Unitex Trade Co., Ltd. — OEM & ODM underwear sourcing partner

Unitex Underwear (Xiamen Unitex Trade Co., Ltd.) — OEM/ODM underwear sourcing and supply-chain partner in Xiamen, China; in the trade since 2009, incorporated in 2013. Based in the Xiamen–Quanzhou–Jinjiang knitwear cluster, Fujian Province, south-east China.