Blazer Size Conversion Chart

How US, UK and EU blazer sizes relate

Blazer sizes use two systems at once, number sizes and letter sizes, and the number systems differ by country. In the US and the UK, blazer number sizes are usually the same number, so a 40 in one is generally a 40 in the other. In the EU system, the number is about ten higher, so a US 40 is generally an EU 50, a US 42 is generally an EU 52, and a US 38 is generally an EU 48.

Letter sizes sit on top of the number sizes and are less precise. One letter can cover two number sizes, which is why a size M blazer from one maker can feel like a 40 while another feels closer to a 38. When you order across systems, convert to the number size first and use the letter only as a rough check, because the number carries more information.

Reading the conversion table

The table on this page lists US and UK sizes side by side with their usual EU equivalents and the letter size that most often covers them. Start from the size you know, read across the row, and note the equivalent in the system you need. Then check your chest measurement against the range for that size, because your body measurement is more reliable than any converted label.

Treat the table as a general guide rather than an exact rule. Some makers use a different EU offset, and some letter sizes cover a wider range than the table shows. If a listing gives both a number and a letter, trust the number, and if it gives a chest range in inches or centimetres, trust that above both labels.

Letter sizes hide real differences

Letter sizes are convenient but they hide differences that number sizes reveal. A size L can mean a 42 in one range and a 44 in another, and that two inch gap changes how the shoulders and chest fit. This is why two blazers labelled L can fit very differently even when they come from makers in the same country.

When a listing shows only a letter, look for the chest range or the garment measurements in the product details before ordering. If the listing shows neither, treat the purchase as a guess and check the return policy first. A blazer is a tailored garment, so a guess at the size is more likely to disappoint than a guess at a looser garment.

Ordering a blazer from another country

Cross border orders add two risks, a size system you do not know and a return that costs more and takes longer. Reduce both by measuring your chest, waist, shoulder width and sleeve length first, then comparing those numbers with the brand chart in the country of origin, not with a converted label from a general table.

Check the stated garment measurements too, especially shoulder width and sleeve length, because those decide blazer fit and vary more between countries than chest does. If the seller lists measurements in centimetres, convert them with the calculator or divide by 2.54, and write the converted numbers down before you choose a size.

Short, regular and long lengths in conversions

Size conversions cover width, but blazer length is a separate choice that conversions do not show. A US 40 regular and a US 40 long have the same chest number, yet the long version adds about an inch at the sleeves and an inch at the body, which changes where the hem falls. When you convert a size from another country, check whether the listing says regular, short or long, because the length label travels with the size and matters as much as the number.

Short lengths suit shorter frames, long lengths suit taller frames, and regular lengths suit most people in the middle. If you convert a size and the length label is missing, look at the stated sleeve length and back length in the product details before you order. A converted chest size that is right can still leave sleeves that cover your hands or a hem that sits too high, so length is part of the conversion, not an afterthought.

General blazer size conversion chart

The chart below gives usual equivalents between US, UK and EU blazer sizes. Treat these as general guides, not as brand sizes. Always check the brand chart for the blazer you are buying.

If the listing gives a chest range in inches or centimetres, use that range instead of the converted label, because body measurements are more reliable than labels.