Fly opening in boxer briefs or not
Short answer: Short answer: A fly is a practical detail, but it costs two extra seams against the skin. Many people skip it for exactly that reason.
What a fly is
A fly is two layers of fabric lying over each other at the front, so there is an opening without a button. It is also called an opening or a front. It comes with and without an extra cross seam, and the idea behind both is usually the same, which is easy access.
The case for it
A fly makes a toilet visit quicker, especially under a boiler suit or a set of workwear, where you cannot just pull the waistband down. In those situations a small opening feels like a real relief, and that is why many choose it, even when the rest of the underwear is plain. See bamboo underpants for men.
The case against it
Extra layers of fabric mean extra seams and a little more warmth in that spot. If you have sensitive skin or sweat a lot, a model without a fly is often best. Then there are fewer seams that can chafe and less fabric to hold moisture while you move around. See bamboo underwear for men and bamboo clothing for men.
Sensitive skin and seams
Seams are where underwear chafes most often, and a fly adds two more of them right at the front. If you already feel seams in your underwear, that is a good reason to skip the fly. Also check whether the seams are flat, because they rub less against the skin than raised seams do.
The fit is the same
There is usually no difference in fit between a model with a fly and one without. The cut is the same all the way round, and only the front piece is built differently. You can choose your usual size and expect the underwear to sit the same, whether or not there is an opening.
Does the fly wear out first
Not normally. The extra seam sits in a spot with little strain, so it is not stressed the way the waistband and gusset are. You do not need to fear that the fly gives up before the rest of the underwear, as long as you wash it by the label and do not wear it out needlessly.
What the packaging says
Makers use different words for the same thing. Look for phrases like with fly, with opening or open fly when you read the product description. If nothing is stated, there is probably no opening, but if you are unsure, look at the picture of the front and count the layers of fabric.
Who benefits from it
If you have a job where you wear a boiler suit or thick workwear, a fly can be a really good thing. If you mostly sit in ordinary clothes, it is rarely needed, and you do not gain much from it. Think about where and when you would most often use an opening before you choose.
In short
A fly is practical under boiler suits and workwear, but it brings two extra seams and a little more warmth at the front. If you have sensitive skin or sweat a lot, a model without is often better. The fit is the same and the fly does not wear out first, so the choice is mostly about comfort.
Frequently asked questions
Is there a difference in fit
No, the cut is usually the same all the way round. Only the front piece is built differently, so you can choose your usual size without worry.
Does the fly wear out first
Not normally. The extra seam sits in a spot with little strain, so it is not stressed like the waistband and gusset, and it does not wear out faster.
What is it called on the packaging
Often with fly, with opening or open fly. If nothing is stated, there is probably no opening, so look at the picture of the front and count the layers of fabric.
