Leather jacket size conversion chart: US, UK, EU, Italian, Japanese and Korean sizes
Quick answer: US and UK men’s jacket sizes are the same number, and that number is your chest measurement in inches. A 40 fits a 40-inch (102 cm) chest. Most European and Italian labels add 10 (a US 40 is a 50), Japanese numeric labels add 2 (a 42), and Korean labels run on a 5-step scale (a 105). Letter sizes (S, M, L) are the least reliable of all.
The chart below gives every common conversion in one place, in inches and centimetres. Under it is the part most size charts leave out: from about size 42 upward, the familiar “+10” shortcut drifts away from the European body-measurement standard, one reason a “converted” European jacket can feel tight across the chest on larger men.
Men’s jacket size conversion chart
Use this to translate a label. The chest figure is the body chest the size is meant for (the number on a US/UK label, in inches, converted to cm).
| US / UK | EU / Italian (usual label) | Japan (numeric) | Korea | Letter size (typical) | Body chest (in) | Body chest (cm) |
|---|---|---|---|---|---|---|
| 34 | 44 | 36 | 90 | S | 34 | 86 |
| 36 | 46 | 38 | 95 | S | 36 | 91 |
| 38 | 48 | 40 | 100 | M | 38 | 97 |
| 40 | 50 | 42 | 105 | M | 40 | 102 |
| 42 | 52 | 44 | 110 | L | 42 | 107 |
| 44 | 54 | 46 | 115 | L | 44 | 112 |
| 46 | 56 | 48 | 120 | XL | 46 | 117 |
| 48 | 58 | 50 | 125 | XXL | 48 | 122 |
| 50 | 60 | 52 | 130 | XXXL | 50 | 127 |
How to read it:
- US and UK use identical numbers for tailored jackets and most leather jackets. The number is the chest in inches; the letter after it on suits (S, R, L) is the length, not the width.
- EU / Italian: the usual retail conversion is US/UK + 10. Many Italian and other continental brands label this way.
- Japan: numeric jacket labels run US + 2 in the common conversion tables, but many Japanese brands use their own scales (1-2-3-4, or S-M-L letters that can run smaller than US letters). Always check the brand’s chart.
- Korea: the 90-95-100-105 scale steps by 5 for each US size.
- Letters have no fixed meaning between brands. Treat them as a rough guide and go by measurements.
Why the “+10” rule breaks above size 42
The European standard for size labelling (EN 13402, now carried into ISO 8559) measures men’s jackets by chest girth in centimetres. Under the German and Northern European numbering, a jacket size is roughly half the chest in cm: size 48 covers a 94–97 cm chest, size 50 covers 98–101 cm, and so on in 4 cm steps.
Compare that with what a US/UK chest really measures:
| US / UK size | Real chest (cm) | Size by “+10” | Size by chest in cm (German standard) | Gap |
|---|---|---|---|---|
| 36 | 91 | 46 | 46 | none |
| 38 | 97 | 48 | 48 | none |
| 40 | 102 | 50 | 50–52 | borderline |
| 42 | 107 | 52 | 54 | one size |
| 44 | 112 | 54 | 56 | one size |
| 46 | 117 | 56 | 58 | one size |
| 48 | 122 | 58 | 60–62 | one to two sizes |
| 50 | 127 | 60 | 64 | two sizes |
The reason is simple arithmetic. One inch is 2.54 cm, so each 2-inch US step adds about 5 cm of chest, while each European step adds only 4 cm. The two scales start together around 36–38 and slowly pull apart.
What this means in practice:
- Up to US 40, the +10 shortcut works for most brands.
- From US 42 up, check whether the brand sizes by the European body standard or by the shortcut. If its chart says “size 52 = chest 102–105 cm” and your chest is 107 cm, you need a 54, even though the shortcut says 52.
- When a brand publishes a chest measurement for each size, trust the measurement over any conversion, ours included.
Convert by measurement, not by label
Labels are a starting point; your measurements are the answer. You need two numbers:
- Your body chest: a soft tape around the fullest part of the chest, under the armpits, level and snug, breathing normally. Our fit guide shows how to measure shoulders, sleeve and back length too.
- The jacket’s garment chest: lay the jacket flat, zipped, and measure straight across from armpit seam to armpit seam (“pit to pit”). Double it for the full garment chest.
The garment chest should be larger than your body chest. That extra room (the “ease”) is what lets you move and wear a layer underneath. How much you want depends on the style: a fitted biker or café racer jacket needs the least, a flight jacket or anything worn over a knit needs more. If a seller lists only a body-chest size chart, they have already built ease into the pattern.
A worked example
Your chest measures 104 cm (41 in). You are looking at three jackets:
| Jacket | Its chart | Your size |
|---|---|---|
| US brand, sizes in inches | 40 = 40 in chest, 42 = 42 in chest | 42: at 41 in you’re between sizes, so size up for a jacket you’ll layer, or try both if it’s a slim biker |
| Italian brand, +10 labels | 50 = US 40, 52 = US 42 | 52 |
| German-standard brand | 52 = 102–105 cm | 52, the same as above, because you sit near the point where the two scales still agree |
Now repeat it with a 112 cm (44 in) chest: the US jacket is a 44, the +10 Italian label is a 54, but a brand that follows the cm standard would put you in a 56 (110–113 cm). Buying a 54 from that brand would leave the chest about one size tight, and leather stretches very little.
Leather and shearling adjustments
Size charts are written for cloth jackets. Leather and sheepskin behave differently:
| Material or style | How it fits against the chart | What to do |
|---|---|---|
| Cowhide, horsehide | Firm at first; gives slightly at elbows and shoulders, never in length | Buy for shoulders and sleeve length; a snug chest is fine |
| Lambskin, goatskin | Softer, relaxes more with wear | Stay true to size or close-fitting |
| Shearling (wool inside) | The wool takes up room, so it runs small | Measure over the layers you’ll wear; often one size up |
| Aviator / B-3 | Cut roomy by design to go over layers | Follow the maker’s chart closely; see our aviator and B-3 guide |
| Biker / café racer | Cut close to the body | If between sizes, size down only if the shoulders still fit |
More on how each hide behaves: cowhide vs lambskin vs goatskin. For shearling warmth and layering, see what shearling is.
Short, regular and long
On suits and some leather jackets, a letter after the size gives the body length. Tailors don’t agree exactly on the cut-offs, but most published guides fall close to this:
| Fit | Your height (approx.) | Typical back length of a tailored jacket |
|---|---|---|
| Short (S) | up to about 5 ft 7–8 in (170–173 cm) | about 28–29.5 in (71–75 cm) |
| Regular (R) | about 5 ft 8 in to 6 ft 1 in (173–185 cm) | about 30–31.5 in (76–80 cm) |
| Long (L) | about 6 ft 1–2 in (185–188 cm) and over | about 32–33.5 in (81–85 cm) |
Leather jackets are usually shorter than tailored jackets (a biker or bomber ends at the waist), so use these only to choose between short, regular and long versions of the same jacket. The sleeve is the measurement that most often goes wrong; see the sleeve check in our fit guide.
Buying from another country: a checklist
- Measure your chest in both inches and cm and write both down.
- Find the brand’s own size chart; ignore generic charts (including this one) if theirs gives measurements.
- Check whether the chart lists body or garment measurements.
- If you are a US 42 or larger buying a European size, check the chest in cm, not the +10 shortcut.
- For shearling, allow for the wool lining and your winter layers.
- Read the returns and exchange policy before ordering. Returning a heavy jacket across a border can be slow and costly.
Frequently asked questions
What is a size 50 leather jacket in US sizes?
On most Italian and European labels, a 50 is a US/UK 40, for a chest of about 40 in (102 cm). On a brand that follows the European cm standard strictly, a 50 is for a 98–101 cm chest, which is closer to a US 39–40.
Are UK and US jacket sizes the same?
Yes, for men’s tailored and leather jackets the numbers match: both are the chest measurement in inches. A UK 42 is a US 42.
Do Japanese jackets run small?
Japanese numeric labels usually run two numbers above US sizes (a Japanese 42 is a US 40), and Japanese S-M-L letter sizes can be cut smaller than US letter sizes. Go by the brand’s chest measurement in cm.
Should I size up for a shearling jacket?
Often, yes. The wool inside takes up room, and you will usually wear a sweater under it. Measure your chest over the layers you plan to wear and compare it with the jacket’s garment chest.
What if I am between two sizes?
For a fitted leather jacket, choose the size whose shoulders fit; leather gives a little in width over time but never in length or across the shoulder seams. For a jacket you’ll wear over knits, take the larger size.
Sources (checked October 2026): EN 13402 size-labelling standard and its chest-girth size bands (summarised on Wikipedia, “Joint European standard for size labelling of clothes” and “Clothing sizes”); tailoring guides from Nathan Tailors and SuitsExpert on chest-inch sizing and short/regular/long heights. Brand charts vary: always check the maker’s own measurements.