Men’s Casual Suits vs Formal Suits: What’s the Difference?

To the uninitiated, the differences between a men’s casual suit and a more formal one can appear very subtle indeed. Often to the point of creating confusion. Dressing for a formal occasion but unsure whether you’re doing it right? Wanting to look more casual, but don’t know how? Our guide to the differences between men’s formal and casual suits will have you up to speed in no time.

How to Tell the Difference Between a Formal and Casual Suit for Men?

Single or Double Breasted?

Men’s suit jackets typically come in one of two main styles; single or double-breasted. In practice both can be worn in formal and informal situations, depending on everything else that’s going on with the suit and its accessories.

All other things being equal, though, a double-breasted suit is the more formal of the two styles. So if you’re looking for a men’s casual suit, and really want to avoid anything too dressy, the single most important step you can make towards achieving a causal style is simply opting for a single-breasted jacket.

On the flip side, if you’re out to create a smarter and more elegant impression, merely the act of choosing a double-breasted suit will already take you half of the way there.

As we’ll see, though, the difference between a formal and casual suit is more about the combined effect of a number of different elements than any single design feature. So don’t feel like you are forced to choose one particular style of jacket if your personal preference would actually be to go with the other. It’s more about the total look than any single element.


As with the front fastening (above), there are two main types of lapel that you’ll see in everyday use: notch and peak (there’s also the shawl collar, but that’s a whole other story and not a design you’ll see very often in the wild). Of the two styles, a peak label is undoubtedly the more formal looking. And, not coincidentally, it is also the standard type of lapel that you’ll find on a double-breasted jacket.

Meanwhile, notch lapels are more commonly seen than peaks. Unsurprisingly, then, notch lapels are also considered more causal. To be clear, you can certainly make a very formal impression in a jacket with notch lapels, but this will depend a great deal on how you wear it.

In short, if your goal is to put together an appropriate look for a formal occasion, peak lapels will give instant credibility. Meanwhile, although a jacket with notch lapels can also appear very formal if all the other details combine to make it so, notch lapels are more versatile than the peak in that they can easily be dressed down, too. As a general rule, though, men’s casual suits will always feature notch lapels.

Aside from the shape of lapels, the final thing to mention when considering casual vs formal suits is lapel width. Skinny lapels are clearly more casual. So if trying to put together a relaxed look, you will probably want to avoid truly wide lapels. However, just keep in mind that looser, wider fits have come to dominate the catwalks over recent seasons, so the extreme skinny look is clearly on its way out of fashion.


Single-breasted suits come in one, two, three (and occasionally even four) button varieties. A two-button fastening is widely acceptable in most professional and social situations – either formal or informal.

Don’t take this as a hard, fixed rule, but generally the more buttons a jacket has, the more likely it is to look formal. A single-button suit, by contrast, somehow always feels much more casual.

It’s the same situation with double-breasted suits; four buttons feel quite relaxed, while six buttons create a primmer, more ceremonial air.

Of course, just because you have all these buttons doesn’t mean you’ll necessarily want to use them. In fact, the bottom button on a two or three-button single-breasted suit should never be fastened anyway. But beyond this, you can influence how smart or casual your three-button suit feels, simply by deciding whether or not to fasten the top button. Hint; two closed buttons usually look more conservative.

Also, consider that the type of buttons a suit has will equally influence the impression it makes. Mother of pearl will always look smart, especially when in a similar color to the suit fabric. And brass will look equally formal on a double-breasted blazer. But less conventional materials such as wood, or even otherwise quite classic buttons in a contrasting color, will be more appropriate on men’s casual suits.


Unsurprisingly, most men’s formal suits come in rather reserved colors such as dark blue and charcoal gray. Meanwhile, men’s casual suits are free to come in a much wider range of unusual, and even downright eccentric, colors and patterns.

It’s not just about the color, though. The type of cloth also plays a part in deciding