A trouser either fits at three points or it does not fit at all. The rise, the seat and the break decide everything else.
Most people who say they cannot wear trousers have worn the wrong rise. It is almost always the rise. The cut is blamed, the size is blamed, occasionally the body is blamed, and the actual problem is an inch and a half of fabric between the waistband and the crotch seam.
There are three places a dress pant can fail. Get all three right and the cut, the color and the price matter far less than anybody pretends.
The Rise
The rise is the distance from the crotch seam to the top of the waistband. It decides where the trouser sits on you and therefore where your waist appears to be.
A high rise sits at or just above the natural waist. It gives the longest leg line and it is the most comfortable to sit in for a full day, because the waistband rests on the narrow part of the torso rather than sliding.
A mid rise sits a couple of inches below. This is what most ranges cut by default and it suits the most people, which is not the same as suiting you.
A low rise sits on the hip. It is the hardest of the three to wear to work and the easiest to get wrong.
The test in the fitting room: fasten the trouser, then sit down and stand up twice. If the waistband has moved, the rise is wrong for you. No amount of taking in at the waist fixes a rise.
The Seat
The second failure point and the one most people cannot diagnose. Stand sideways to a mirror. A trouser that fits at the seat has smooth fabric with no horizontal pulling below the waistband and no pooling under the seat.
Horizontal drag lines mean it is too tight through the seat, whatever the waist measurement says. Loose fabric hanging below it means the opposite. Both are alterable, and a good alterations shop charges very little to do it.
If you routinely fit at the seat and gape at the waist, that is the single most common trouser problem there is, and taking in the center back seam by an inch fixes it permanently.
The Break
The break is what the hem does when it meets the shoe. It is the most visible of the three and the cheapest to correct.
No break means the hem finishes just above the shoe with the fabric hanging clean. Modern, and the safest with a wider leg.
A slight break means the hem rests on the shoe and creates one soft fold. The most traditional and the most forgiving.
A full break means the fabric folds twice or more. It reads as too long, and almost always is.
The hem is set for one shoe height. If you own the trouser and love it, buy the shoe first and hem to it.
Three points decide a trouser: the rise, the seat and the break. Two of them are cheap to alter and one of them is not.
The Cuts, and What Each One Is For
Straight Leg
The same width from knee to hem. The most versatile cut there is and the one that works with the widest range of shoes. If you own one dress pant, own this.
Wide Leg
Widening from the hip or the knee. Elegant, comfortable and the most forgiving to sit in. It wants a high rise and a hem close to the floor, and it looks wrong with anything but a defined waist above it.
Tapered
Narrowing toward the ankle. Neat and practical, and the easiest to wear with a flat shoe or an ankle boot. Watch the width at the calf, which is where a taper either skims or clings.
Flare
Fitted to the knee, opening below it. The most fashion-led of the four and the one most dependent on the hem being exactly right, because there is a lot of fabric below the knee and nowhere to hide a bad length.
Pleated
Not a leg shape but a front detail, and worth knowing. Pleats add room across the front of the hip and hang best in a fabric with some weight. In a very light cloth they pop open and look untidy.
Fabric
The thing that decides whether a trouser still looks like a trouser at four in the afternoon.
A cloth with weight holds a crease at the front and recovers overnight. A very light one creases at the knee and the seat within an hour of sitting down, and no amount of pressing prevents it.
A little stretch helps at the seat and the thigh. A great deal of stretch makes a trouser behave like a legging, which is comfortable and reads as considerably less smart.
Texture forgives. A cloth with some surface to it disguises creasing and ordinary wear far better than a flat one, which is why a subtly textured trouser outlasts a plain one in practice as well as in appearance.
Wearing Them
Tuck something in, or wear something that ends at the waistband. The point of a good rise is the line it creates, and a top that covers the waistband hides the only thing the trouser was doing for you.
Match the shoe tone to the trouser where you can. A dark trouser with a dark shoe reads as one continuous line. A dark trouser with a pale shoe draws attention to the hem, which is fine if the hem is right and unhelpful if it is not.
Keep the layer above at the waist or open. A blazer left undone over a straight trouser is the most reliable work outfit there is, and it survives every change in what is fashionable.
For a full guide to the wider shapes and how they differ, the trouser edit covers the rest.
Trousers Worth Tailoring Around
Common Questions
What Are Dress Pants for Women?
Dress pants are tailored trousers cut in a cloth with enough weight to hold a crease and a clean line, as distinct from casual trousers such as jeans or chinos. They usually have a flat or pleated front, a proper waistband and a finished hem, and they are cut straight, wide, tapered or flared. The defining feature is the fabric and the finish rather than the leg shape.
Are Chinos Dress Pants?
Not usually. A chino is a casual trouser in cotton twill with a flat front and patch or slash pockets, and it sits below dress pants in formality. In a relaxed office a dark, well pressed chino will pass for business casual, but it will not stand in for a dress pant at a formal event or in a traditional workplace. The giveaway is the cloth: twill reads casual where a smooth suiting cloth does not.
The Short Version
Check the rise first, because it is the one thing that cannot be altered. Check the seat in profile for drag lines. Set the hem to one shoe height and keep to it. Buy a straight leg in a cloth with some weight, tuck something in, and the trouser does the rest.