A decade ago, when hashtag-menswear and the Pitti Peacock made suits ubiquitous, there was only one fit that mattered. Slim, trim, Mad Men-inspired tailoring – complete with pocket squares, sprezzatura tie and double monks – replaced the boxy duds your dad wore. Trouser breaks were out, a flash of ankle was in.

Now, though, you’ve got options. Slim’s still around, but so’s skinny. The Savile Row classic endures too – looser but more structured – as well as a new breed of baggy fits that are slowly trickling from the runway down into the real world.

To help you navigate this new world of sartorial choice, we’ve broken down each type of suit so you know how it should fit, how to wear it – and whether it will actually suit you.

Skinny Suits

Topman

Legend has it that when Hedi Slimane debuted his groundbreaking skinny tailoring in the early ’00s, the late Karl Lagerfeld dropped six-and-a-half stone so that he could fit into it. The fit favoured by every rock band since has hung around, especially on the high street, where summer suits fly out in time for proms and weddings. It’s a fit with a youthful feel, largely because it’s most flattering on bodies that time hasn’t yet softened.

Some designer suits still appear in this guise, especially ones with rock ‘n’ roll overtones: think Saint Laurent, John Varvatos and Celine. But the bulk comes at the more affordable end, where it’s not uncommon to see an experimental all-over pattern or even a green suit. Be aware that it’s an unforgiving look, in every sense – skinny suits draw the eye and, unless they’re well cut or have some give in the fabric, can be pretty uncomfortable. It’s not something your tailor would ever recommend. “Don’t do it,” says Jonathan Loe, bespoke co-ordinator at London formalwear store Oliver Brown. But if you insist on a suit as skinny as your jeans, here’s how.

How Skinny Suits Should Fit

Topman

A skinny suit should fit like a second skin, but that doesn’t mean sizing down. The shoulders should sit flush with your own, and you should still be able to button the jacket without the fabric pulling. The waist will nip in very aggressively and the trousers, especially, will taper from the waistband and end bang on the ankle – if they hit your shoes, get them shortened.

Skinny suit trousers can be an issue for guys with bigger thighs. Jeans solve this by adding stretch, although this is not generally the best look in more formal fabrics. “Fabric needs a bit of ease to drape and provide comfort,” says Loe. If you absolutely must, there’s muscle-fit tailoring, be warned though that wearing that much polyester and viscose will make you a fire hazard. Sometimes, stretchy fabrics are best left in the gym.

Dress it up: Add a waistcoat, just make sure there’s enough space under the already snug jacket.

Dress it down: Go full rock ‘n’ roll and pair the jacket with an animal-print shirt, skinny jeans and Chelsea boots.

Slim Suits

Marks & Spencer

Slim-fit suits are arguably the least on-trend, but perhaps still the most physically flattering. They elongate your body shape, they offer enough room to move, and they have a classic air that makes them relatively timeless. They’ve also been the default for the last decade, which means that, fashion being the fickle beast it is, they’re now old hat.

That said, if you’re looking for a fallback suit – the kind of navy two-piece that you’ll break out for weddings, funerals and job interviews – then slim isn’t a bad choice. It won’t date, and it will also always make you look good – the extra shape it creates makes your legs look longer and your waist seem slimmer, which will be handy as the body beneath inevitably changes. And by the time it does, slim will doubtless have come back into style.

How Slim Suits Should Fit

Ted Baker

Everything starts from the shoulders. They should lie flat against your own, as should the chest fabric. “No pulls across the back or puckering at the front, or the lapels lifting away from the body,” says Loe. On a two-button jacket, the top one should sit just above your navel – shorter guys can go a bit higher, taller guys a bit lower, to balance your proportions.

The jacket nips in enough at the waist that you can daylight between sleeve and torso when your arms are hanging, but you should also be able to fit your hand between the lapel and your chest when it’s buttoned. The trousers will taper, but less so than on a skinny fit. If you’re slim, go for a pair that narrow through the thigh; if you’re more athletic, try a pair that tapers from below the knee. If the taper’s quite gentle, you can get away with a bit of fabric on your shoes, but generally, they should just kiss the laces.

Dress it up: Beware of over-accessorising. Take a note from Don Draper and stick to a tie and subtle pocket square.

Dress it down: The modern creative’s uniform – swap the shirt for a plain tee, and your smart shoes for white sneakers.

Regular Suits

Brooks Brothers

The most classic cut, stolid and unyielding to fashion trends. As designers oscillate between skinny and baggy, regular fit always looks a little fusty – it’s never directional, which means it’s never fashionable. But it is always safe. A regular-fit suit today will still look good in 20 years, which is perhaps why it’s the default on Savile Row, where they make suits you could hand down to your children.

That’s not to say that they don’t look good. In fact, because you can be confident they’ll never date, they make great investment pieces, and by picking premium fabrics or going a brand or two more luxury than usual, you get all the benefits of improved materials and better cutting technique, with the same cost-per-wear you would from something cheaper but more fashion-forward.

How A Regular Suit Should Fit

Ted Baker

Again, shoulders are key, but so’s the collar – it should sit flush with your shirt’s, no wrinkling or standing proud when the jacket’s buttoned. “Shoulders should appear broader, with good shape through the waist without too much suppression,” says Loe. “There should be room in the back for movement and a bit of room at the bicep area.” The jacket will probably be longer, too – level with your thumb’s second knuckle, rather than its first.

The trousers should sit on your waist, not your hips, and fall either straight or with a very subtle taper into the ankle. That extra fabric means you can play around with things like pleats (fashionable now, but probably not in a decade) or turn-ups. Whether you go cuffed or not, the hems should sit on your laces with a slight ‘break’ – that’s a small fold in the fabric at your shin.

Dress it up: They’re classic, so don’t mess with the formula; shirt, patterned tie, shiny black shoes.

Dress it down: The trousers can sub in for chinos – try them with trainers and a denim jacket.

Relaxed Suits

COS

Runways in recent seasons have been awash with tailoring of a very specific kind. Loose, billowing, indebted to late-eighties Armani and late-nineties sportswear. “The materials of sportswear have allowed young designers and brands to innovate by using different materials, because it’s more acceptable, and using different silhouettes,” says menswear designer Matthew Miller. “This [baggy] silhouette that we’re seeing coming into the suit at the moment, it all stems from sportswear.”

That non-conformist approach to construction means you can bend the style rules, too. These loose suits have formal roots, but are designed more for weekends than work. “I wear it wherever I want to, with a hoodie, with sneakers,” says Miller. “I’d never wear it with a pair of shoes – it feels really square.”

How A Relaxed Suit Should Fit

COS

It’s a look that lives on a knife-edge – go too oversized and it just looks like you’re dressed up in dad’s work clothes. The body can be loose, but you need to nail the trousers and sleeves – the former at your wrist, the latter with a small break on your shoe. “If they’re too long, it gives the impression of the whole suit being too big and shapeless,” says Loe.

Beyond that, you can go as loose as feels comfortable (the bigger the suit, the more on-trend). Double-breasted jackets are particular of the moment, especially worn open and mixed with other, unexpected elements, like hoodies and joggers.

Dress it up: Lean into the old-school-meets-new-school vibes with a ’70s roll neck.

Dress it down: Take a note from fashion week cool kids and make an oversized suit jacket your new outerwear, over anything from a T-shirt to a hoodie.