TL;DR (too long; didn't read):
- Never button the bottom button of a suit jacket or a waistcoat, as jackets are cut to hang open at the bottom.
- Unbutton a single breasted jacket when sitting, while a double breasted jacket stays buttoned.
- Show between a quarter and half an inch of shirt cuff, and keep the jacket long enough to cover the seat.
- Keep the tie darker than the shirt for contrast, and never wear suspenders and a belt at the same time.
- For black tie, match lapel facing, bow tie, cummerbund, and trouser braid in the same satin or grosgrain.
Menswear rules you should follow and why they matter
There are plenty of menswear rules you can happily break, and some you probably should. But there are others worth following, and not because they're traditional or because some self-appointed expert insists on them. They're worth following because there's an actual, sensible reason behind each one. Have you ever looked at a man in a suit and sensed something was slightly off, without being able to say exactly what? More often than not, it's one of these rules being quietly ignored.
The rules that genuinely earn their place tend to fall into a few camps. Some are about proportion, the balance that makes an outfit look right. Some are about how a garment is actually designed to fit and function, so breaking them literally works against the clothing. And some simply stop you doing something that never made much sense in the first place. None of them are arbitrary, which is exactly why they've stuck around. They sit at the heart of good classic tailoring proportions for men.
In this piece we'll walk through the rules I actually follow and the reasoning behind each, kept deliberately concise. We'll cover the buttons you should never fasten, how to get your jacket's proportions right through cuff and length, a couple of easy styling rules for ties and suspenders, and the black tie details that must always match. Learn the why behind each one and you won't just be following rules, you'll understand your clothes. Let's begin with the buttons.
The two bottom buttons you should never fasten
Let's start with the rule that trips up more men than any other, and it's genuinely non-negotiable: never button the bottom button of your suit jacket or sport coat. It's one of the clearest tells that someone doesn't quite understand how tailored clothing works. There's a practical reason behind it, too. Modern jackets are cut with the expectation that the bottom button stays open, so the moment you fasten it you start pulling the front of the jacket in a way it was never designed to sit. The skirt stops falling properly, the quarters close up, and the whole silhouette distorts. The old shorthand is "sometimes, always, never", meaning on a three-button jacket the top is sometimes, the middle is always, and the bottom is never. The same logic carries over to the three-roll-two jackets you see far more often today, and it runs through almost every well-cut piece in a good three button suit jacket and beyond.
The same principle applies to the waistcoat. If you're wearing a three-piece suit, always leave the bottom button of the waistcoat undone. The popular origin story points to King Edward VII, who reportedly began leaving his undone as he gained weight because it was more comfortable when seated, whether in a chair or on a horse, and because he was the king, other men followed suit until it became convention. How much of that is fact and how much is folklore is up for debate, but there's a genuine practical benefit: leaving it open gives the waistcoat a little more freedom around the waist and hips, especially when you sit down.
While we're on the subject of sitting, there's a related button rule worth knowing. When you're wearing a single-breasted jacket, you should unbutton it as you sit down. A single-breasted jacket is designed to hang properly when buttoned and standing, so sitting with it fastened pushes the fabric up, creates creasing, and puts needless stress on the button and cloth. The exception is the double-breasted jacket, which traditionally stays buttoned even when seated. Small details, all three, but each one quietly signals whether a man understands what he's wearing.
Getting jacket proportions right with cuff and length
Two of the most important rules have nothing to do with buttons and everything to do with proportion, starting with your shirt cuff. When you're wearing a suit or sport coat, you should always show a little shirt cuff beyond the jacket sleeve. The generally accepted range is between a quarter and half an inch, and personally I lean toward the upper end of that. It's a tiny amount of fabric, but visually it makes a huge difference: that sliver of cuff looks polished and intentional, and it tells you someone has actually paid attention to how his clothes fit.
When there's no cuff showing at all, one of three things is usually going on: the jacket sleeve is too long, the shirt sleeve is too short, or the wearer simply doesn't know or care. You can overdo it in the other direction, though. Once you're showing an inch or more, it tips into looking sloppy, as if your jacket sleeves are just too short. So aim for that quarter-to-half-inch window and you'll hit the mark every time. Getting this right is part of what separates a considered look from a careless one, and it applies across every navy blazer and grey trousers outfit in your wardrobe.
The other big proportion rule is overall jacket length, and the guiding principle for classic tailoring is simple: your jacket should cover your backside. An easy way to check is the curl-your-fingers test. Stand naturally with your arms at your sides, make a loose fist, curl your fingers under the hem of the jacket, and they should just kiss it. About a decade ago, during the slim-fit era, jackets got dramatically shorter, which is fine if a sportier, fashion-forward look is your aim. But for classic tailoring, length is critical to the balance of the whole outfit, and a jacket that's too short looks as though it simply doesn't fit, even when the shoulders and body are correct. This is one rule I really wouldn't play around with.
Simple styling rules for ties and suspenders
Not every rule worth following is about fit and proportion. Some are about styling, where something simply looks right even if you've never consciously registered the rule behind it. A good example: your tie should generally be darker than your shirt. You may not think about it when you're getting dressed, but there's clear logic to it. The shirt acts as the background, and the darker tie creates contrast, establishes a clear visual hierarchy, and helps draw the eye upward toward your face, which is exactly where you want attention to land.
Flip that around with a dark shirt and a lighter tie and you drift into mafioso territory, which is a deliberate look rather than a classic one. There's one exception I genuinely like, though: going fully tonal, matching the shirt and tie in the same colour. Done consciously, it has a little flair and a touch of throwback style, and it works precisely because it's so clearly a choice. But for traditional tailoring, the darker tie wins. It frames the face, creates contrast, and simply looks right, pulling together a classic dark suit combinations look with no effort at all.
The second styling rule has no room for interpretation: never wear suspenders and a belt at the same time. Braces and a belt do exactly the same job of holding up your trousers, so wearing both is completely redundant and, frankly, looks absurd. Choosing between them really comes down to formality. With a suit, and always with formalwear, suspenders are the natural choice, because they preserve the clean line of the trousers with no belt cutting across the waist, ideally paired with side-adjuster trousers rather than belt loops. As things get more casual, business casual and below, that's when a belt makes sense. And if you do wear braces with tailoring, choose button-on ones, since clip-ons look juvenile.
Black tie details that must always match
There's one area of menswear where the rules matter more than almost anywhere else, and that's black tie. It's one of the most prescriptive dress codes for men, pretty cut and dried, and that's precisely what makes it such a reliable barometer for who's done their homework and who's just playing dress-up. Black tie is all about the details, and getting them right signals real understanding in a way almost nothing else does.
Four details in particular need to match: your lapel facing, bow tie, cummerbund, and trouser braid. The facing is the contrasting material on the lapel of your tuxedo jacket, and the braid is the stripe running down the outside of your trousers. The rule is simple. If your lapel facings are satin, then you want a satin bow tie, satin cummerbund, and satin braid. If the facings are grosgrain, then it's grosgrain across the bow tie, cummerbund, and braid. There's no right or wrong between the two finishes themselves, it's purely a matter of preference, but mixing them is absolutely out. Build your classic dark suit combinations for the evening around one finish and keep it consistent throughout.
Where people most often slip up is treating the bow tie and cummerbund as separate accessories rather than parts of a single, complete ensemble. That's the heart of black tie: it's full of tiny details most people won't consciously notice, yet they instantly reveal who knows their stuff and who doesn't. Satin with satin, grosgrain with grosgrain, no exceptions. Get this right and you'll look entirely at home in a room where plenty of other men quietly won't.
Get the classic details right with Westwood Hart
Here's the thing about nearly every rule we've covered: following them is far easier when your clothes are actually built to the right proportions in the first place. At Westwood Hart, that's exactly what we do. We make custom-tailored suits and sport coats to your measurements, so your jacket is cut to the correct length to cover your seat, your sleeves are set so you can show that clean quarter to half inch of cuff, and the buttoning point sits where it should. When the foundation is right, looking polished stops being a daily struggle and simply becomes how your clothes fit.
Whether you're after an everyday business suit, a three-piece with a properly cut waistcoat, or black tie done correctly down to matching satin or grosgrain details, we'll help you get every proportion and finish right. You can design your own suit using our online configurator, choosing the cloth, the cut, side adjusters instead of belt loops, and the small touches that separate considered tailoring from off-the-peg guesswork. Browse our timeless menswear outfits to see what's possible, and let's build you something that follows these rules effortlessly, because it was made to.
Frequently asked questions about menswear rules you should follow
Why should you never button the bottom button of a suit jacket?
Modern jackets are cut with the expectation that the bottom button stays open. Fastening it pulls the front of the jacket out of shape, stops the skirt falling properly, and distorts the whole silhouette. The old shorthand is "sometimes, always, never" for a three-button jacket, with the bottom button always left undone.
Should you unbutton your jacket when sitting down?
Yes, for a single-breasted jacket. It's designed to hang properly when buttoned and standing, so sitting with it fastened causes creasing and puts stress on the button and cloth. A double-breasted jacket is the exception and traditionally stays buttoned even when seated.
How much shirt cuff should show below a jacket sleeve?
Between a quarter and half an inch is the accepted range, with many men preferring the upper end. No cuff at all usually means the jacket sleeve is too long or the shirt sleeve too short, while showing an inch or more looks sloppy, as though the jacket sleeves are simply too short.
Can you wear suspenders and a belt at the same time?
No. Braces and a belt both hold up your trousers, so wearing both is redundant and looks odd. Choose based on formality: suspenders with suits and formalwear to keep the waistline clean, and a belt for business casual and more relaxed outfits.
What has to match in a black tie outfit?
Four details must share the same finish: the lapel facing, bow tie, cummerbund, and trouser braid. If the lapel facing is satin, everything else should be satin; if it's grosgrain, everything else should be grosgrain. Mixing the two finishes is the most common black tie mistake.