The shoulder test: the one fit check worth doing first

If you only ever check one thing on a jacket, coat or structured shirt, check the shoulders.

The reason is practical rather than aesthetic. A tailor can take in the waist, shorten the sleeves, shorten the body, move the buttons and slim the legs. The shoulder is the one part that cannot be meaningfully altered — the sleeve head is set into the armhole with the whole structure of the garment built around it, and recutting it means rebuilding the jacket. Most alterations tailors will simply decline, and the ones who will charge more than the jacket is worth.

Everything else is negotiable. This is not.

What correct looks like

The shoulder seam ends where your shoulder ends. Find the bony point at the outer end of your collarbone where the arm begins. The seam should sit on it, or within about a centimetre.

The shoulder line is flat. Looking from the side, the top of the shoulder should run smoothly from the collar to the sleeve head with no dip in the middle and no bulge at the end.

No divot below the seam. A horizontal dent or ripple in the sleeve just below the shoulder seam means the sleeve head is too big for the armhole, or the shoulder is too wide.

The three ways it goes wrong

Too wide

The seam sits down your upper arm. The shoulder line droops past the end of your shoulder, and there is often a soft collapse where the seam should be.

This is the most common problem in off-the-peg tailoring and the most visible from a distance — it reads as "borrowed" from across a room, even to people who could not say why.

Deliberately dropped shoulders are a different thing. On a casual overshirt, a sweatshirt or an oversized coat, the seam is designed to sit well down the arm and the whole garment is cut to suit it. The tell is consistency: on a designed drop, the sleeve head is soft and unstructured and the armhole is large. On a badly fitting structured jacket, there is padding inside a seam that is in the wrong place, and it looks collapsed rather than relaxed.

Too narrow

The seam sits inboard of your shoulder point. You will see it before you feel it — the sleeve head bulges upward in a small peak because the fabric has nowhere to go, and the armhole binds when you reach forward.

Narrow shoulders limit movement in a way wide ones do not, so this is the version you notice while wearing rather than in a mirror.

Right width, wrong slope

Less discussed and very common. Shoulders vary in slope from quite square to quite sloped, and jackets are cut for an average.

If yours are more sloped than the cut assumes, fabric collects in a soft horizontal fold under the collar at the back. If they are squarer, the jacket lifts away from your neck and the collar gaps.

This one is alterable — a tailor can adjust the shoulder slope — and it is worth asking about, because it is the difference between a jacket that looks fitted and one that looks nearly fitted.

Doing this online

You cannot feel an armhole through a screen, so use the measurement.

Take the shoulder width off a jacket you own that sits correctly: lay it flat, face down, and measure straight across the back from shoulder seam to shoulder seam. Write it down. This is the number to compare, and it is far more reliable than your chest measurement for structured garments.

In product photos, look for:

• A back view. The shoulder line and any collar gap show up there first.
• A flat lay. The armhole shape is visible, and a small armhole on a structured jacket is a sign of a closer fit.
• The model's size and height. A jacket that sits correctly on a 185cm model in a large will not automatically sit correctly on you in a large.

If the shoulders are right and the body is loose, buy it — that is a cheap alteration and a good outcome. If the body is perfect and the shoulders are not, put it back. That one does not get better.

The short version

• Shoulders cannot be altered. Everything else on a jacket can.
• The seam belongs on the bony point at the end of your shoulder.
• Fabric bulging above the seam means too narrow; a drooping seam means too wide; a fold under the collar means the slope is wrong.
• A dropped shoulder is a design, not a fault — the tell is whether the sleeve head is soft or padded.
• Measure the shoulder width of a jacket you already like, and shop with that number.