The three points a tailor can fix and the label cannot

Two men in the same jacket, same size, same price. One looks like the jacket was made for him and the other looks like he is wearing his brother. The difference is three measurements, and none of them is the one printed on the label.

The collar gap

Stand straight and look at the back of the neck in a mirror with a second mirror. The jacket collar should rest against the shirt collar along its whole length, with no daylight between them and no bunching. A gap means the jacket is hanging off the back of your neck instead of sitting on your shoulders, usually because the balance of the garment does not match your posture.

This is the fault that reads most clearly as cheap, from across a room, on any garment at any price. It is also correctable, by a tailor, for about 60 to 120, by adjusting the collar seam. If you own one jacket with a collar gap, that is where the next hundred should go before any new purchase.

The shoulder line

The shoulder seam should finish at the point where the flat of your shoulder turns down into your arm. Not before, which pulls and creases diagonally from the armhole. Not after, which drops the sleeve head into a soft collapse halfway down the upper arm.

This is the measurement to get right in the shop, because it is the one alteration that is genuinely expensive. Re-cutting a shoulder means detaching both sleeves, reshaping the pads and the canvas and setting them again, which runs from 180 to 350 and is beyond the skill of most high street alteration counters. A jacket with the wrong shoulder is not a bargain at any discount.

Buy the shoulder, alter everything else.

The sleeve and the cuff

The jacket sleeve should end so that about one centimetre of shirt cuff shows with your arms relaxed at your sides. Half a centimetre reads as a jacket slightly too long, two centimetres reads as a jacket borrowed for the afternoon.

Shortening from the cuff costs 40 to 80 and takes a week. If the jacket has working buttonholes, the alteration has to be done from the shoulder instead, which is three times the price, which is the small joke hidden inside a feature sold as a mark of quality.

The four that are easy and the two that are not

• Easy: sleeve length, trouser length, waist suppression on a jacket, taking in a shirt body. Each 30 to 90, each done in a week.
• Moderate: moving buttons, reshaping a lapel roll, replacing a lining. 80 to 250.
• Hard and rarely worth it: shoulders, chest width, anything that changes where the armhole sits.
• Impossible: making a garment larger by more than the seam allowance, which on ready to wear is usually two centimetres and sometimes nothing at all.

What this does to the buying decision

Once you know which faults are cheap to fix, the shop becomes a simpler place. Try the size that fits the shoulder and the chest, ignore everything hanging loose below the ribs, and add eighty to the mental price of anything that needs the waist and the sleeves brought in. That is still the cheapest way to buy a jacket that looks made for you, and it is available at every price level in the market.

It also explains an otherwise odd piece of advice. A 400 jacket that fits your shoulder, altered for 120, will look better than an 1,800 jacket that does not, and that comparison holds all the way up the price list. The cloth is the part you notice second.

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