Six alterations worth paying for, and four that never are

The useful principle is structural, not financial. A garment is built outward from a few load-bearing decisions — the shoulder line, the armhole, the rise, the way the pieces are seamed — and everything else is adjustable. Alterations that work are the ones that leave those decisions alone. Alterations that disappoint are the ones that try to undo them.

This is why the same job can be twelve pounds on one jacket and a polite refusal on another, and why the answer to is this worth altering depends less on the price of the garment than on where it is wrong.

Worth it: taking in the side seams

The most common and most transformative job on anything from a shirt to a coat. Side seams are straight, accessible, and carry no structure that cannot be re-sewn. A tailor can remove a surprising amount here and the garment will look as though it was cut that way, provided the shoulder and armhole were right to begin with.

It is also the alteration that makes a size up wearable, which is the practical route through a range that grades badly: buy for the widest part of you, then have the rest brought in.

Worth it: shortening sleeves from the shoulder on a tailored jacket

Shortening from the cuff is cheap and fine on a shirt. On a structured jacket it moves the buttons, changes the taper and flattens the cuff detail. From the shoulder — opening the head of the sleeve and resetting it — costs more, takes longer, and preserves everything that made the sleeve look like a sleeve. If the jacket is worth keeping for five years, pay for it.

Worth it: hemming, always, on everything

The single cheapest change with the largest effect, and the one most consistently skipped. A trouser hem that breaks in the right place and a coat that stops at the intended point on the leg are most of what reads as expensive. It costs less than the taxi you took to the shop.

Worth it: moving buttons on a shirt or coat

A gaping placket is usually a button-spacing problem rather than a size problem: the button sits above or below the widest point and the fabric has nowhere to go. Adding one button between the two that pull, or shifting the whole run by a centimetre, is a ten-minute job that removes a daily irritation. Ask for it on anything you wear weekly.

Worth it: replacing a lining

Linings wear out first, at the underarm and the seat, and they are the cheapest component in the garment. A coat with a shot lining and good cloth is worth relining. A coat with good lining and tired cloth is not worth anything.

Worth it: adding a waist stay or a hook and eye

Small, unglamorous, and it holds a wrap dress closed, keeps a skirt from rotating and stops a coat from pulling open when you sit. Any tailor will do it while you wait. Almost nobody asks.

Not worth it: letting out a garment that has no seam allowance

Check before you buy. Turn the garment inside out and look at the side seam: a generous allowance shows as a good centimetre and a half of spare fabric either side of the stitching. Fast-fashion construction frequently leaves three or four millimetres and an overlocked edge, which is nothing. There is no skill that adds fabric that is not there.

Not worth it: making a shoulder narrower on a coat

The shoulder is the garment. Reducing it means reconstructing the armhole, resetting the sleeve, and often adjusting the collar and the front edge — a rebuild priced accordingly, and one that rarely comes back looking like the coat you liked. If the shoulder is wrong, the coat is wrong. Put it back.

Not worth it: resizing a knitted garment

Knit is a structure, not a cloth. Cut it and it runs; take it in and the seam becomes a rigid line through something that is supposed to stretch. Knitwear is either the right shape or it is a candidate for being worn as it is.

Not worth it: any alteration to a garment you do not already like

The most expensive job in the shop is the one performed on something you bought because it nearly worked. A tailor can make a garment fit. Nothing available at any price will make you want to put it on.

How to find someone

Dry cleaners with a sewing machine visible behind the counter are usually competent at hems and side seams and honest about the rest. For anything structural, ask a menswear shop who does their jacket work; that answer is almost always the best tailor within a few miles, because men’s tailoring keeps them in practice on armholes.

Take one thing first. A hem is a ten-pound audition, and what comes back tells you everything about whether to bring the coat.