How Should a Suit Jacket Fit?

Check the shoulders first, then run the button test, the hem check, the sleeve check and the collar check, and learn which problems a tailor can fix.

Quick take

• The shoulder seam should end exactly where your shoulder ends and your arm begins, because the shoulders are the one part a tailor cannot realistically rebuild.
• On a buttoned jacket, a flat hand should slide inside at the chest, the lapels should lie flat, and the waist should taper slightly without pulling.
• The hem should just cover your seat and reach roughly the middle knuckle of your thumb with your arms hanging relaxed at your sides.
• Jacket sleeves should end just above the wrist bone, showing about half an inch of shirt cuff, and most jackets need a sleeve alteration.
• Buy for the shoulders and tailor the rest: waist, chest, sleeves and collar are fixable, while shoulder reconstruction is rarely worth the cost.

A suit jacket that fits well will look better than an expensive one that does not. Fit is the biggest single factor in whether tailoring reads as sharp or sloppy, and it matters more than colour, fabric or brand. The upside is that almost everything can be checked in a few minutes in the fitting room.

Where Should the Shoulder Seam Sit?

The shoulder seam should end exactly where your shoulder ends and your arm begins, resting snugly along the shoulder’s natural shape with no overhang. When the seam spills over onto the arm, the jacket is too large. When it stops short of your shoulder edge and rides upward, it is too small.

The shoulders come first because they are the one part of a jacket a tailor cannot realistically rebuild. Chest, waist, sleeves and hem can all be adjusted; restructuring a shoulder means taking much of the jacket apart, and the results are rarely worth the money.

Signs of a wrong shoulder are easy to spot. A jacket that is too tight stretches the fabric, creases and restricts movement. One that is too loose leaves extra fabric and a seam that drops below the shoulder, often with a small dent, called a divot, on the arm toward the back of the sleeve head. A clean, smooth line from the top of the shoulder down into the sleeve means you have found your base size.

What Does the Button Test Tell You About the Chest?

The button test shows whether the chest is too tight or too loose: button the top button on a two-button jacket, or the middle one on a three-button, and check whether a flat hand slides comfortably between the buttoned edge and your chest. If your hand will not fit, the jacket is too tight. If you can make a fist in there, it is too loose.

Lapels tell the same story. Buckling lapels mean the jacket is too small. Horizontal wrinkles across the back or chest, or an X-shaped fold spreading out from the closing button, are size problems worth fixing, not quirks of the fabric. A correctly fitted chest skims the body with no stress lines, and the lapels lie flat against it.

How Should the Waist Be Shaped?

The waist should taper in slightly, just enough to give the jacket shape without pulling or bunching. A boxy, shapeless profile reads as a sack rather than a suit.

This is also the most forgiving area. A waist that is too loose is one of the easiest alterations, since a tailor can take it in or let it out through the side seams. A waist that pulls open at the button is a different problem, and when the fit is too tight through the middle, going up a size beats counting on alterations. The buttoning point itself should land close to your natural waist.

How Long Should the Jacket Be?

The hem should just cover your seat. If it sits above your bottom, the jacket is too short. If it falls well past the bottom, longer than your arms, it is too long.

Two rules of thumb point to the same place. The classic measure is that the hem falls roughly midway between the collar and the floor. The quicker version is to let your arms hang relaxed at your sides: the hem should reach about the middle knuckle of your thumb, or roughly the middle of your hand.

Length is harder to adjust than most other parts of the jacket. A tailor can usually trim a hem by a small amount, around two centimetres, before the pocket placement starts to look off, but more than that changes the proportions of the whole jacket.

Where Should the Sleeve End?

The jacket sleeve should end just above the large bone at the wrist, leaving about half an inch, roughly 1.5 centimetres, of shirt cuff visible beyond it. That sliver of cuff is one of the easiest signs of a finished-looking suit. Our guide to how dress shirt sizing works explains how shirt sleeves get measured in the first place.

Off the rack, almost no jacket has a perfect sleeve length, so plan on an alteration. One catch: if the jacket has working buttonholes at the cuff, as many better suits do, the sleeves must be shortened from the shoulder rather than at the cuff, which costs more.

Check how the sleeves hang as well. With your arms at your sides, the sleeve should fall cleanly, with no divots or spiralling wrinkles near the top, which can signal a mismatch between the sleeve and your natural arm angle.

What Does a Collar Gap Tell You?

A gap between the jacket collar and your shirt collar means the jacket does not match your shoulders or posture. A correct fit has the jacket collar resting naturally against the shirt, with neither pressure nor space between the two layers.

Check from the back as well as the front. A collar gap shows as visible space at the back of the neck. The opposite problem is a collar roll, when extra material gathers in folds behind the neck because the jacket does not match your body.

The collar should stay close to your neck even when you move your arms, within reason. A tailor can correct collar problems, so a small gap is not a deal breaker, but a jacket that fits well here off the rack saves you an alteration, and collar work can be extensive.

Do Armholes and Movement Matter?

They matter as much as anything in the mirror, because a jacket can look right standing still and fail the moment you move. Raise your arms in front of you; the jacket should let you move without pulling across the chest or lifting the whole jacket with you.

Armhole height drives much of this. Higher armholes allow better mobility, while low ones limit how freely you can move and make the fabric tug at the chest or stomach. Construction plays a role too. Soft, unpadded shoulders with higher armholes move better, while heavier cloths such as tweed and flannel hold a more structured shape that suits a Canadian winter, though the added bulk makes the shoulders matter even more.

Two small checks finish the fitting room visit. The vents at the back hem should stay mostly closed while you wear the jacket, though new jackets are usually sewn shut, so snip the threads at home with a seam ripper before judging. And if the suit is for a specific occasion, picture the right shirt and shoes with it; our guide to job interview outfits shows how the whole look comes together.

What Can a Tailor Fix Later, and What Can’t They?

A tailor can rescue a lot, but not everything. The fixable list covers most of the checkpoints above: taking in or letting out the waist and chest through the side seams, shortening sleeves, trimming a hem slightly and adjusting the collar. The unfixable list is short but decisive. Shoulders that are too big or too small are almost impossible to correct, because the alteration is complex, costly and rarely looks natural.

Fabric changes the picture. Lightweight cloths such as tropical wool and linen drape close to the body and show any pulling across the chest if the jacket is snug, so leave a little more ease. Heavier fabrics hold their structure and can make shoulders look more defined, but they add bulk, so fit errors show in different ways.

The same checkpoints apply when shopping secondhand. Judge the shoulders first, then estimate the alteration bill before you commit; our breakdown of the real cost of tailoring secondhand finds helps you decide whether the numbers add up.

Run these checks in order, shoulders first, and you will know within a few minutes whether a jacket deserves to leave the store with you.

Your style questions

Q: Can a tailor fix suit jacket shoulders?

A: Almost never. Restructuring a shoulder means taking much of the jacket apart, and the result is rarely worth the cost, so decide on shoulder fit in the store.

Q: How much shirt cuff should show under a jacket sleeve?

A: About a quarter to half an inch, roughly 1 to 1.5 centimetres. Few jackets get this right off the rack, so most sleeves need altering.

Q: Is a jacket that is too big or too small easier to fix?

A: Too big, by far. Waist and chest can be taken in through the side seams, while a jacket that pulls at the button is better solved by sizing up.

Q: What causes a collar gap?

A: The jacket collar not matching your shoulders or posture, showing as visible space at the back of the neck. The reverse problem is a collar roll, when extra material gathers in folds behind the neck.