The margin for error when it comes to wearing a well-fitting suit is long and wide, especially if the one you’ve been pulling out for weddings, interviews and every office party in between is either too long or too wide.

Few of us are blessed with the model build to be able to wear an off-the-peg version without needing a few nip and tucks from a tailor (the suit, not us).

However, much like visiting the barbers for a trim, it pays to be armed with knowledge – in this case knowing what good fit looks like.

So, whether you’re in the market for a new suit and want to give your tailor the best canvas to work with, or simply want to run your current collection through this handy guide before considering alterations, here are the basic rules of suit fit.

1. The Jacket


Everything starts with the shoulders. These are the hardest parts of a jacket to adjust and if you go wrong here, sometimes not even the best tailor can save you.

The shoulders should lay flat and the seam should end where your natural shoulder ends. If this seam sits too high or too low it throws the whole jacket off and can create a ripple effect, particularly down the arms.

Good Suit Shoulder FitImage: M&S AW15


A jacket is going to be worn both buttoned (when standing) and unbuttoned (when seated), so it’s important the fit is checked both ways.

The button should fasten without struggle and the material should not strain (i.e. create wrinkles around the button). Once fastened, you should be able to insert a flat hand into the suit under the lapels, again, without it pulling.

In terms of length, the top button of a two-button suit jacket should sit in line with, or just above, your navel. On a three-button design this should be measured by the middle button: standing with your arms by your sides, the bottom of the jacket should fall in line with your knuckles – this should make it just long enough to cover your trouser zip.

Good Suit Jacket Body FitImage: Mango Man Fall 2014


Unlike shoulders, arm length is fairly easy for a tailor to alter, providing they are bought slightly too long rather than too short.

Jacket sleeves should hit around where the base of your thumb meets your wrist. This positioning will ensure the cuffs of any (properly fitting) shirt will be exposed by the right amount; about a quarter to half an inch.

Good Suit Blazer Sleeve LengthImage: Brothers AW14


A poorly fitting collar is usually the knock on effect of a problem elsewhere. One that is too loose will sit away from the neck, while if it’s too tight, it will bunch up above the back. The collar of the jacket should sit comfortably against the collar your shirt.

It’s not wise to rely on a tailor to fix this problem; opt for a different jacket to avoid paying out dearly for alterations to the jacket’s construction.

Good Suit Blazer Collar FitImage: Boglioli AW15

The Trousers


A suit should be tested as it is meant to be worn, which means trying it on with a good pair of smart shoes.

Start with width: the ideal fit gives slightly more room in the thigh and then tapers below the knee. The old foe, strain, can appear when there isn’t enough room in the top part of the leg. No one wants to see the outline of what’s in your pocket (or anything else for that matter).

When it comes to length, you’ll often hear the term ‘break’ – this refers to the small fold of material that appears where your trousers cuff hits your shoe. Too much of this results in unsightly puddling.

For a clean, modern look aim for little to no break, but make sure your ankles aren’t permanently on show.

Lookbook Inspiration - Good Suit Trouser Break

jaeger aw14pal zileri ss13barneys new york 2013reiss aw13gieves & hawkes aw13m&s best of british aw14reiss aw14sanahunt aw13charles tyrwhitt 2014


Your natural waist is around two inches below your navel. When sat here, your trousers should not require a belt to stay up, nor should they squeeze you into agony.

Worried about needing a little extra room post-lunch? Find a pair fitted with a side-adjuster or ‘daks-strap’.

Suit Trousers With Side AdjustersGo Side adjusters help deal with the natural fluctuations our waistlines tend to go through


The seat is where you sit, essentially it’s your butt. As tempting as it may be to try to emphasise your curves, the material here should drape with the natural shape of your body.

Much like your jacket, if the material is strained, it’s too tight. Similarly, a sag in the material means the seat is too loose, though this is easier to take in than let out.