Clothing Size Converter

Introduction to international clothing size systems

Buying clothes across borders fails in a very specific way: the number on the label means something different in every market, and it means something different again for every garment category. A shopper who wears a UK 14 dress is a US 10 and an IT 46, but the same shopper reading a men's jacket chart would find that the US and UK numbers agree there and the European number sits ten higher. A men's trouser label converts with yet another offset. This converter is built around that reality. Instead of pretending there is one universal formula, it carries a separate ladder for each garment category and lets you move between the US, UK, general European, Italian and Japanese systems within that ladder.

The reason for the mess is historical. British and American tailoring grew out of inch measurements taken directly from the body, so a men's jacket labelled 40 was drafted for a 40-inch chest and a trouser labelled 32 was drafted for a 32-inch waist. Continental European tailoring standardised on centimetres, and the jacket number settled on roughly half the chest in centimetres, which is why a 40-inch chest turns into a European 50. Women's ready-to-wear never had that anchor at all. American women's sizes were set by a 1940s statistical survey, then drifted downwards for decades through vanity sizing, leaving a numbering scheme that is essentially an index rather than a measurement. Japan built its own ladder for womenswear using odd numbers, and its footwear sizes simply state foot length in centimetres, which is the only system on this page that is unambiguous by construction.

Because there is no shared origin, there is no shared conversion. The practical consequence is that the single most common online-shopping error is applying a remembered offset to the wrong category: converting a men's trouser label with the jacket rule, or converting a men's shoe with the women's shoe rule. Both mistakes land you a garment that is exactly two sizes away from correct. The converter and the practice game below are both designed around that failure mode.

How to use the clothing size converter

1. Pick the garment category first. This is the step that people skip, and it is the step that determines which conversion ladder applies. Women's dresses, women's shoes, men's jackets, men's trousers, men's dress shirts and men's shoes each have their own table.
2. Choose whether you are starting from a size label you already wear or from a body measurement. Starting from a label is faster; starting from a measurement is more reliable if you are not sure the label you own was honest.
3. If you chose a label, select the system you know (US, UK, EU, IT or JP) and then the label itself. The list of available labels changes with the category, because the ladders do not share values.
4. If you chose a measurement, enter the number and select inches or centimetres. The hint under the field tells you which dimension that category is drafted from: bust, chest, waist, neck or foot length.
5. Select Convert size. The result panel lists the equivalent label in every system that category supports, the letter size where one exists, the body measurement band the size is drafted for, and the neighbouring sizes on either side so you can see how close you are to a boundary.
6. Use Copy result to paste the conversion into a note or an order form, and Reset to clear the form back to its defaults.

If a conversion puts you near the edge of a band, run the calculation again one size up and one size down. Boundary cases are where returns come from, and knowing you sit 1 cm below a step change tells you far more than the single label does.

The conversion formulas behind each size system

Every ladder on this page reduces to one of four ideas, and each one is worth understanding separately.

Unit conversion. Every inch-based ladder converts to centimetres with the exact, defined factor of 2.54, and back again:

Formula: L cm = 2.54 × L in and L in = (L cm) / 2.54

and

Index ladders (womenswear). US, UK, EU, IT and JP women's dress numbering all step by the same amount per size, so they differ only by a constant. Taking the US number as the index:

Formula: UK = US + 4, EU = US + 32, IT = US + 36, JP = US + 5

Measurement ladders (menswear tailoring). A men's jacket number is the chest in inches in the US and UK, and roughly half the chest in centimetres on the continent. Since half of 2.54 is 1.27 and the ladders step in twos, the relationship collapses to a clean additive offset over the normal size range. Trousers work the same way from the waist, but with a different offset because the waist ladder starts lower:

Formula: EU jacket = US chest + 10 and EU trouser = US waist + 16

and

Direct centimetre labels. A European dress-shirt size is simply the collar circumference in centimetres, so the conversion is the unit conversion itself, rounded to the nearest whole centimetre:

Formula: EU collar = round(2.54 × US collar)

That rounding is why the European collar ladder skips values. A 15.5-inch collar is 39.4 cm and labels as 39; a 16-inch collar is 40.6 cm and labels as 41, so no European shirt is ever labelled 40 in this ladder.

Footwear. Japanese shoe sizes are Mondopoint labels, meaning the number is the foot length in centimetres. The European ladder descends from the Paris point, a unit of two thirds of a centimetre applied to the length of the shoe last rather than the foot, which is why European shoe numbers climb faster than a centimetre a size:

Formula: JP = foot length cm and EU ≈ 3 / 2 × (last length cm)

and

The single trap worth memorising in footwear is that the US-to-UK step is not the same for the two lines: women's US labels sit about two sizes above UK labels, while men's US labels sit about one size above. Reading a men's chart with the women's rule produces a shoe a full inch too long.

Category-by-category conversion tables

The tables below are the same data the converter uses. Reading them side by side is the fastest way to see that the offsets are not shared.

Note the third table carefully. At a foot length of 25 cm a woman wears US 8 and a man wears US 7, but the UK labels are 6 and 6 as well — the two lines converge in the UK system and diverge in the US system. That single row explains most cross-line shoe returns.

Worked example: a UK 14 dress and a 40-inch jacket

Start with the dress. Select the women's dresses category, choose UK as the known system and 14 as the label. The converter locates the row where the UK column reads 14. That row carries US 10, EU 42, IT 46, JP 15 and letter size M, and it is drafted for a bust of about 95 cm. Checking the arithmetic against the formulas: US 10 plus 4 is UK 14, US 10 plus 32 is EU 42, US 10 plus 36 is IT 46 and US 10 plus 5 is JP 15. The band shown for that row runs from the midpoint with the size below to the midpoint with the size above, roughly 93 cm to 97 cm, or 36.6 in to 38.2 in.

Now the jacket. Switch the category to men's jackets and suits, keep US as the known system and choose 40. The result is UK 40, EU 50, IT 50 and letter size M, drafted for a chest of about 102 cm. Confirm it: 40 inches is 40 × 2.54 = 101.6 cm, and half of that is 50.8, which the European ladder rounds to 50. The same additive shortcut, EU = US + 10, gets there in one step.

The instructive part is what happens if you carry the dress offset across. A shopper who remembers "European is 32 higher" and applies it to the jacket would ask for a European 72, which does not exist, or worse, would apply "European is 10 higher" to the dress and ask for a European 20, which does not exist either. Where the mistake actually bites is between the two menswear categories, because both offsets produce real labels: applying the trouser rule of +16 to a 40-inch chest gives European 56, a genuine jacket size that is three sizes too big. That is the exact trap the Fitting Room Rack game below drills.

Finally, run the same jacket from a measurement. Switch to measurement input, enter 102 and leave the unit on centimetres. The converter finds the nearest charted chest anchor, which is the 102 cm row, and returns the identical set of labels. Entering 40.2 in gives 102.1 cm and lands on the same row, which is a useful confirmation that the two input paths agree.

Measuring accurately before you convert

A conversion chart can only be as good as the number you feed it. Use a flexible tape and take every measurement over thin clothing or bare skin, standing upright and relaxed. For the bust, run the tape around the fullest point with the tape level all the way round and parallel to the floor; a tape that rides up at the back adds two or three centimetres and can push you a full size. For the chest, measure under the arms across the widest part with arms down. For the natural waist, find the narrowest point between the ribs and the hips and do not hold your breath or pull the tape tight. For a shirt collar, measure around the base of the neck where the collar sits and add roughly 1 cm of comfort allowance if you plan to wear a tie.

Feet are measured differently. Stand on a sheet of paper with your heel against a wall, mark the tip of the longest toe, and measure from the wall to the mark. Do it late in the day, when feet are at their largest, and measure both feet: an asymmetry of 3 to 5 mm is common and you should buy for the larger foot. Because Japanese shoe sizing is literally that number in centimetres, a good foot measurement gives you a Japanese size directly with no chart in between.

Take each measurement two or three times and use the median rather than the first reading. Where two readings straddle a band boundary, the converter's neighbouring-size line will show you both candidate labels, and the fit preference for the garment — a fitted dress versus a relaxed jacket — should decide which way you round.

Limitations and assumptions of size conversion

This tool converts between size labels using published body-measurement charts, and that framing carries several assumptions you should hold onto. First, it describes the body a size is drafted for, not the finished garment. Two jackets both labelled EU 50 can differ by several centimetres across the chest depending on how much ease the pattern carries, so a slim-cut 50 and a relaxed 50 are not interchangeable. Second, women's ready-to-wear numbering is not standardised in any enforceable way: vanity sizing has shifted US labels downwards over decades, and a vintage US 10 corresponds to a much smaller body than a current one. Third, the European footwear ladder is a convention rather than a standard, and half-size drift of one Paris point between brands is normal — treat an EU shoe result as plus or minus half a size.

Fourth, the tables here cover the common ranges of each ladder and stop there. Petite, tall, plus, half and portly-drop cuts all exist and are not modelled, and neither are children's sizes, which use age and height rather than an index. Fifth, the converter uses a single anchor measurement per category, so it cannot see the relationships that actually determine fit: the chest-to-waist drop for a suit, the hip-to-waist ratio for a dress, sleeve and inseam length, or foot width, which many European lasts encode as a separate letter. Sixth, brands that publish their own chart are always more authoritative than a general conversion, and where the two disagree the brand chart wins.

Use this converter to narrow a decision from five candidate labels to one or two, then confirm against the retailer's own chart and, where available, customer fit reviews. For tailored or expensive items, or anywhere returns are costly or slow, order the size the chart gives and plan on alteration rather than assuming a cross-system label will be exact.

Clothing size conversion questions shoppers ask

Sources: body-measurement definitions and the size-designation approach follow ISO 8559-1:2017, Size designation of clothes — Part 1: Anthropometric definitions for body measurement; European labelling practice follows ISO/TR 10652 and the related EN 13402 size-designation work; US women's and men's body-measurement tables are published as ASTM D5585 and ASTM D6240; footwear length systems, including Mondopoint and the Paris point, are summarised in the shoe size reference; and the inch is defined as exactly 2.54 cm by NIST Office of Weights and Measures. Ladders are conventional and vary by brand, so confirm against each retailer's own chart.