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A 40-inch chest takes a size 40 Regular suit with a 34-inch trouser waist. Enter your chest measurement and height to find your jacket size, length, and waist — and check the full 36–52 chart below.
Your suit size is your chest measurement rounded up to the next even number, your trouser waist is your suit size minus 6 inches, and your jacket length comes from your height. Three inputs, one lookup, no guessing in the fitting room.
Suit sizes are built on one measurement: your chest. The number on the jacket is your chest in inches, rounded up to the next even number — so a 40-inch chest is a 40, and a 41-inch chest is a 42, because suits are sold in even sizes only. The letter after the number is the length, and it comes from your height: Short is under 5′8″, Regular is 5′8″ to 6′1″, and Long is over 6′1″. At the defaults — a 40-inch chest at 5′10″ — that gives a 40 Regular, written 40R. The trouser waist follows the standard drop-6 rule: suit size minus 6 inches, so a 40 suit pairs with a 34-inch waist. Centimetres are inches times 2.54, so a 40-inch chest is 101.6 cm and a 34-inch waist is 86.4 cm.
| Suit size | Chest (in) | Chest (cm) | Waist (in) | Waist (cm) |
|---|---|---|---|---|
| 36 | 36 | 91.4 | 30 | 76.2 |
| 38 | 38 | 96.5 | 32 | 81.3 |
| 40 | 40 | 101.6 | 34 | 86.4 |
| 42 | 42 | 106.7 | 36 | 91.4 |
| 44 | 44 | 111.8 | 38 | 96.5 |
| 46 | 46 | 116.8 | 40 | 101.6 |
| 48 | 48 | 121.9 | 42 | 106.7 |
| 50 | 50 | 127.0 | 44 | 111.8 |
| 52 | 52 | 132.1 | 46 | 116.8 |
Rounding convention, stated plainly: suit sizes are whole even numbers, so an odd chest measurement always rounds up to the next even size; centimetres are inches times 2.54, rounded to one decimal.
| Output | Formula | What it means |
|---|---|---|
| Suit size | Chest rounded up to the next even number | 40 in → 40R at the defaults. |
| Jacket length | Under 5′8″ Short; 5′8″–6′1″ Regular; over 6′1″ Long | 5′10″ → Regular at the defaults. |
| Trouser waist | Suit size − 6 in | 40 − 6 = 34 in at the defaults. |
| Chest in centimetres | Chest in × 2.54 | 40 in = 101.6 cm at the defaults. |
| Waist in centimetres | Waist in × 2.54 | 34 in = 86.4 cm at the defaults. |
This is the standard US suit-size convention, not a fitting. Brands vary by about one size, and cuts vary more: a slim cut runs tighter in the chest and waist than a classic cut at the same size, and the drop-6 waist is the standard, not a law — athletic and relaxed cuts use different drops. Measure with a soft tape around the fullest part of your chest, level all the way around, over a shirt, breathing out naturally. Height bands are the common convention, but sleeve and body length also depend on arm length and torso length, so tall men with short arms and short men with long torsos should still try the jacket on. Always check the brand's own chart before ordering, and use a tailor for anything the chart does not cover.
Bright Side Kit. "Men's Suit Size Chart: Jacket, Chest & Waist Lookup" https://brightoolbox.com/mens-suit-size-chart/ Accessed October 24, 2026.A 40 Regular at 5′10″, with a 34-inch trouser waist: a 40-inch chest is 101.6 cm and the waist is 86.4 cm.
You round up to a 42R, with a 36-inch trouser waist (91.4 cm). Suits are sold in even sizes only, so an odd chest always rounds up to the next even size.
38 inches (96.5 cm): the standard drop is suit size minus 6, so 44 minus 6 is 38.
Regular length, for heights from 5′8″ to 6′1″. S is Short, for under 5′8″, and L is Long, for over 6′1″.
Short is under 5′8″, Regular is 5′8″ to 6′1″, and Long is over 6′1″. A 6′3″ man takes a Long.
That is outside this chart. See a tailor or look for a brand's extended sizes rather than forcing a size from the 36–52 table.
Wrap a soft tape around the fullest part of your chest, level all the way around, over a shirt, breathing out naturally. Do not pull the tape tight.
The conversion is inches times 2.54: a 40-inch chest is 101.6 cm and a 34-inch waist is 86.4 cm. European brands label by centimetres, so check the table before ordering.