Fit is four things. Get them right and almost anything else can be lived with.

1. The shoulder

The shoulder seam sits exactly where the flat top of your shoulder turns down into your arm. Not past it, not short of it.

This is first on the list because it is the only measurement that cannot be altered. A tailor can take in a body, shorten a sleeve and move a button. Reconstructing a leather shoulder means dismantling the jacket, and almost no one will do it for a price worth paying.

Too wide: the sleeve head hangs below the shoulder and the jacket looks borrowed. Too narrow: a diagonal drag line runs from the shoulder seam towards the chest, and the sleeve pulls when you reach forward.

2. The chest

Close the jacket fully. You should be able to slide a flat hand — not a fist — between the jacket and your chest.

Tighter than that and the front panels will strain at the closure, which puts stress on the seams and the zip. Looser and the jacket loses the close line that makes leather look deliberate rather than accidental.

Do this check wearing whatever you actually plan to wear underneath.

3. The sleeve

The sleeve should end at the wrist bone, showing about a centimetre of shirt cuff when your arms are down.

Then raise your arms forward to shoulder height. Two things should be true: the cuff should not retreat far up your forearm, and the whole jacket should not lift off your hips. If it does, the armhole is cut too low.

4. The length

Style decides this:

  • Biker / café racer: at or just below the belt line. These are deliberately short — the shape depends on it.
  • Bomber: at the top of the hip, where the ribbed hem can sit naturally.
  • Leather blazer: covering the seat, as a wool blazer would.
  • Oversized / relaxed styles: longer by design, usually a few centimetres below the hip.

Fit by style

The same body needs different amounts of room depending on the cut:

Biker jackets are cut close through the body, with a high armhole and a shaped waist. Size for a t-shirt or a thin knit underneath, not for a jumper.

Café racers are the slimmest cut of all, with minimal ease. If you are between sizes and want to wear anything substantial underneath, take the larger one.

Bombers carry the most ease through the body, with ribbing at the hem doing the shaping. This is the most forgiving style to size.

Blazers follow tailoring rules — the shoulder must be exact, the waist shaped, the length longer.

Oversized styles are still cut, not just enlarged. The shoulder is deliberately dropped, so the usual shoulder-seam rule does not apply — check instead that the drop looks intentional and symmetrical.

Common mistakes

Buying for the shoulder you want. A jacket one size up does not read as relaxed; it reads as the wrong size.

Sizing for a jumper you rarely wear. Size for your usual layer, not your coldest one.

Assuming it will stretch. Leather relaxes and moulds. It does not grow. A jacket that is tight across the back when new will still be tight.

Ignoring the collar. A collar that stands away from your neck means the jacket's back length or neck curve is wrong for you, and it will look wrong in every photograph.