Suit jacket size from your chest.

Worked example

A 40 in chest is jacket size 40 and a height of 5 ft 10 in (70 in) falls in the Regular band, so the size is 40R. EU is 40 + 10 = 50. A suit with the standard 6 in drop has trousers with a 34 in waist.

How it works

US and UK jacket size is the chest in inches to the nearest even number. EU size = US size + 10 (40 is 50). Length by height: Short for 5 ft 4 in to 5 ft 7 in, Regular 5 ft 8 in to 5 ft 11 in, Long 6 ft to 6 ft 3 in, and Extra long at 6 ft 4 in and up.

Suit trousers are cut with a standard 6 in drop, meaning the trouser waist is the jacket size minus 6. If your waist is more than 6 in smaller or larger than the chest, buy the suit as separates or ask a tailor.

Fits differ between cuts and brands. Try a jacket on and check the shoulders first, since they are the hardest part to alter.

Sources and basis (checked 2026-10-05):

• Jacket size = chest to the nearest even inch, EU = US + 10, S/R/L height bands and the 6 in drop: standard menswear and tailoring conventions. Checked 2026-10-05.

FAQ

What size suit is a 40 inch chest?

A size 40 jacket, EU 50, usually with 34 inch trousers.

What does 40R mean?

40 is the chest size in inches, and R means Regular length, for men around 5 ft 8 in to 5 ft 11 in.

What is the 6 inch drop?

The usual difference between jacket size and trouser waist, so a 40 jacket has 34 inch trousers.

How do I measure my chest for a suit?

Under the arms across the fullest part of the chest and shoulder blades, over a thin shirt, with the tape level.

Which is hardest to alter: shoulders or waist?

Shoulders, so fit the jacket to the shoulders and let a tailor adjust the waist and sleeves.