Suit Size Calculator
What size suit am I? Enter your height, weight, and build to instantly estimate your US jacket size, shirt size, and trouser waist.
US suit sizes combine your chest measurement in inches with a length letter: S (short) for heights under 5'8", R (regular) for 5'8"–6'1", L (long) for 6'1"–6'4", and XL for 6'4"+. A 5'10", 170 lb man with regular build typically wears a 40R jacket, 34" trousers, and 15.5" neck shirt. Enter your details below for an instant estimate.
Free · No sign-up · Based on standard US menswear sizing conventions · Trusted by 436+ Nathan Tailors clients
Interactive suit size calculator
Your details
- — Classic fit flatters most balanced proportions.
- — Notch lapels and single-breasted work well.
- — Medium-weight fabrics (260–320g wool) hang best.
How suit sizing works
US suit sizes are written as a number + letter (40R, 42L, 38S). The number is your chest measurement in inches. The letter is the jacket length:
- S (Short) — heights under 5'8" (173 cm)
- R (Regular) — heights 5'8" to 6'1" (173–185 cm)
- L (Long) — heights 6'1" to 6'4" (185–193 cm)
- XL (Extra Long) — heights over 6'4" (193+ cm)
Trouser waist is typically 6 inches smaller than chest for average builds (the “drop”), but can range from 4 inches (larger build) to 8 inches (athletic build). Our calculator adjusts for this automatically.
Common sizes by height and weight
| Height | Weight | Regular build | Athletic build |
|---|---|---|---|
| 5'8" | 150 lb | 38R | 36R |
| 5'10" | 170 lb | 40R | 38R |
| 6'0" | 185 lb | 42R | 40R |
| 6'0" | 200 lb | 44R | 42R |
| 6'2" | 200 lb | 44L | 42L |
| 6'3" | 230 lb | 46L | 44L |
When a calculator isn't enough
Height and weight get you within one size for most bodies. But suits fail on fit, not on size number. What the calculator can't see:
- Shoulder width — wider or narrower than average
- Posture — forward, upright, or swayback
- Chest-to-waist drop — athletic V-shape vs. straight
- Arm length relative to torso
- Thigh circumference for trouser break
For off-the-rack, use the calculator and expect tailoring. For a perfect fit, skip the compromise and go custom — book a fitting or see all 8 measurement guides.
US to European suit size conversion
| US | EU | UK | Chest (inches) |
|---|---|---|---|
| 36R | 46R | 36R | 36" |
| 38R | 48R | 38R | 38" |
| 40R | 50R | 40R | 40" |
| 42R | 52R | 42R | 42" |
| 44R | 54R | 44R | 44" |
| 46R | 56R | 46R | 46" |
Frequently asked questions
How accurate is a suit size calculator?
A good one gets 80% of people within one size. It's a starting point, not a replacement for measurement.
What does 40R mean?
40-inch chest, regular length jacket (heights 5'8"–6'1").
What size suit for a 5'10", 170 lb man?
Regular build typically 40R jacket, 34" trouser, 15.5" neck shirt. Athletic build usually 38R-40R.
What size suit for a 6'0", 200 lb man?
Regular build typically 44R with 38" trouser. Athletic V-shape is notoriously hard off-the-rack — the chest fits but the waist gapes.
Does this work for women's suits?
This calculator is tuned for US men's tailoring conventions. Women's sizing uses a different system — contact us directly for women's custom suits and bridal separates.
Can I order a custom suit with just these numbers?
No — we need 12+ measurements for a custom build. The calculator narrows down your size; our Guided Measurement App at /measurement/new handles the rest, step-by-step with photos.
Why does my size feel different between brands?
Different brands use different fits (slim, modern, classic) at the same nominal size. A 40R can vary by 1-2 inches across brands. Custom eliminates the problem.
Related free tools
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Eight step-by-step guides to measure chest, waist, inseam, and more yourself.
What to look for in your first real suit — fabric, fit, tailoring notes.
Ready for a suit that fits perfectly?
Custom-made suits starting at $109, shipped worldwide in 4 weeks. Rated 5/5 by 436+ clients.