Gomon Custom Clothing · Suit Buying Guide

Men’s Suit Size Guide: How to Find Your Perfect Fit

Short answer: A suit size is really two pieces of information — a chest number (like 40) and a length code (Short, Regular, or Long) — and standard US/UK sizing runs from roughly 34 to 54 across those categories. To find yours, you need four real measurements: chest, waist, shoulder width, and sleeve length, taken with a tape measure rather than guessed from height and weight. The catch is that two men who land on the exact same size number can still have meaningfully different proportions — which is exactly why standard size charts and generic calculators get a real percentage of guys close, but not actually right, and why made-to-measure exists as the fix for that gap.

What a Suit Size Number Actually Means

A suit jacket size isn’t one number — it’s a chest measurement paired with a length code, and most guides skip explaining the second half. Per Wikipedia’s entry on clothing sizes, standard sizing tables for “men’s suits, suit jackets, blazers, overcoats” list equivalent sizes across regions, with the UK/US numbering system running “from 30 to 54.” That number is your chest size in inches, rounded to an even number. The length code that follows it — Short, Regular, or Long — adjusts the jacket’s overall length and sleeve proportions for your height, which is why two men can both wear a “40” and still need different jackets entirely.

European sizing works on a different but related system. Wikipedia notes that French and German standards calculate “suit sizes, s… by chest circumference, b, measured in centimetres,” using a formula rather than a direct inch translation — which is part of why a European size 50 isn’t simply a metric relabeling of a US 40, and why cross-referencing a real conversion table matters if you’re shopping between regions.

How to Measure Yourself, Step by Step

A tape measure and a well-fitting shirt are all you need. Per tailoring guidance from Oliver Wicks, a custom clothier’s measurement guide, here’s how each measurement is actually taken:

• Chest: “Wrap a measuring tape around the fullest part of your chest,” keeping it level across your back. The fit should be “snug, but not tight — you should be able to fit one finger between it and your body.”
• Waist: Measured “at your belly button for higher rise trousers, and two to three fingers below it for low-rise,” aiming for a comfortable fit rather than pulling the tape tight.
• Shoulder width: “Measure straight across your back from the point of one shoulder seam to the other,” wearing a shirt that already fits you well as your reference.
• Sleeve length: “Start the tape measure at the shoulder seam of your shirt and measure down your arm to the second knuckle of your thumb,” with your arm relaxed at your side.

Write down all four numbers before you look at any size chart — guessing your size first and measuring second just anchors you to the wrong number.

A Suit Size Reference Chart

Chest (in)	US/UK Size	Build Note
34–35	34	Smaller frame
37–38	38	Below-average build
39–40	40	Average build — the most common size sold
41–42	42	Above-average build
45–46	46	Larger frame
50+	50–54	Largest standard off-the-rack range

Pair your chest number with a length code based on height: Short generally fits 5’4″–5’7″, Regular fits 5’8″–6’1″, and Long fits 6’2″ and up — though these bands are rough starting points, not guarantees, since torso and arm length don’t scale with height at exactly the same rate for every guy.

The “Drop,” and Why Standard Sizing Breaks Down for Many Builds

“Drop” is the gap built into standard sizing between your jacket size and your trouser size, and it’s narrower than most people realize. Per Oliver Wicks’ measurement guide, “the industry standard is a 6-inch drop” — meaning a standard size 40 jacket is paired with a 34-inch trouser waist by default. If your actual chest-to-waist difference is more or less than six inches, a stock suit’s jacket and trousers won’t both fit correctly straight off the rack, even if the jacket size itself is right.

Standard sizing also assumes one general body shape, and tailoring literature has long built separate formulas to account for the ones it doesn’t. Wikipedia’s clothing sizes entry describes distinct European sizing categories for “short, stocky,” “portly,” and “tall, lean” builds, each with its own adjustment formula relative to the standard chest-based size. That’s a formal acknowledgment of something worth taking at face value: a single chest number was never designed to describe every proportion, and if your build falls into one of these categories, a standard-size chart is working against you by design, not by accident.

When a Chart Genuinely Isn’t Enough

A size chart and a tape measure will get most guys to a workable off-the-rack starting point. They stop being enough when your proportions fall outside what a standard drop and a three-way length code can account for — a shorter torso with longer arms, a fuller midsection with narrower shoulders, or any combination a size label just averages away. That’s the specific gap made-to-measure is built to close: instead of mapping your measurements onto the nearest pre-set size, your actual numbers become the pattern. Our Made-to-Measure Explained guide covers how that process works in full, including why a generic size calculator estimate is a useful sanity check but not a substitute for real measurements.

Getting Your Measurements Right with Gomon

Gomon builds each suit from your own submitted measurements — chest, waist, shoulder, sleeve, and several others — rather than mapping you onto the closest standard size. A detailed measurement guide walks you through taking your own numbers accurately, or you can reference a jacket that already fits you well as a starting point. Standard production runs about 20 days, with a two-week expedited option available, and if a measurement turns out to be off once the suit arrives, the process starts with alterations first.

FAQ

References

• Wikipedia — Clothing sizes — US/UK suit sizing range, European chest-based sizing formulas, and short/stocky, portly, and tall/lean body-type variants.
• Oliver Wicks — How to Measure and Understand Men’s Suit Sizes — step-by-step self-measurement technique and the standard 6-inch jacket-to-trouser drop.

Content prepared for Gomon (customclothinghere.com). Internal links to specific product/collection pages, and to the companion “Made-to-Measure Explained” article, to be added by the Gomon team before publishing.