Suit sizing looks simple on the label — "40R" — but it's actually encoding three pieces of information at once: chest size, length category, and an assumed waist-to-chest ratio. Getting any one of them wrong noticeably affects the fit.

Decoding the Size Label

A label like 40R breaks down as:

  • 40 — chest measurement in inches, measured around the fullest part of the chest under the arms.
  • R — length category: S (Short, for 5'4"–5'7"), R (Regular, for 5'8"–6'0"), L (Long, for 6'1"–6'4").

Understanding "Drop"

Drop is the gap between chest and waist size built into the jacket. A standard drop is 6 inches, meaning a 40 chest jacket is cut for a roughly 34-inch waist. Athletic builds (broader chest, narrower waist) often need a larger drop — 7 or 8 inches — while fuller builds may need a smaller drop of 4–5 inches, sized as "Portly" or "Executive" cuts by some brands.

Suit Size Reference Chart

Chest (in) US Suit Size Height Category EU Size
36 36R 5'8"–6'0" 46
38 38R 5'8"–6'0" 48
40 40R 5'8"–6'0" 50
42 42R 5'8"–6'0" 52
44 44R 5'8"–6'0" 54

Measuring the Three Key Numbers

For an accurate suit size, you need: chest circumference (fullest part, under the arms), waist circumference (where trousers will sit), and height (to determine S/R/L). If you can get even one existing well-fitting jacket to measure, that's far more reliable than estimating from body measurements alone.

🤵 Big-occasion sizing, saved ahead of timeSuits are bought for weddings, graduations, and job interviews — often under time pressure. Save chest, waist, and height to a Size Notes profile well before the event so there's no last-minute scramble.

The Bottom Line

Suits are the least forgiving clothing category to buy as a surprise. If a fitting isn't possible, get chest, waist, and height as accurately as you can, choose a retailer with a generous alteration or return policy, and budget time for a tailor to make final adjustments.