Dress pants from the office to the evening

A pair of tailored trousers in a dark, plain cloth is the most useful thing in a working wardrobe, and most people use about a third of it. They wear the pair to the office, hang it up, and reach for something else when an invitation says “smart” or “cocktail”. Usually there’s no need. If the trousers fit and the cloth is right, they can stay on all day while the rest of the outfit does the changing.

Start with the right pair

The trousers that move best between settings have a few things in common.

• A dark, plain colour. Navy, charcoal and black work at nine in the morning and at nine at night. Mid grey is nearly as flexible. Tan, light grey and patterns are lovely, but they belong to the daytime.
• A smooth worsted wool, or wool with a little stretch. Worsted cloth has a faint sheen and holds a crease, which reads as dressed. Flannel is warmer and softer and looks better with knitwear than with silk.
• A clean front. Flat, or a single shallow pleat. Deep double pleats are a style of their own and look best with their own jacket.
• A pressed crease. It costs nothing, makes the leg look longer and makes the pair look intended.

Fit matters more than any of this. Trousers that pull across the hips or pile up at the ankle look wrong in every setting. The hem should sit on the shoe you wear most, with no more than a slight break, and the seat should fall straight from the hips without clinging. Dress pants that flatter goes through what to look for in the mirror.

At the office

On a normal working day, the trousers’ job is to look calm. Tuck in the shirt or blouse. Wear a belt in a leather that goes with your shoes, or none if the trousers have side adjusters. Leather shoes with a slim sole sit better under a tailored hem than chunky trainers do: a heavy shoe pushes the hem up and makes the break look accidental.

A jacket is optional in most offices now. If you wear one, it doesn’t have to match. Navy trousers under a grey or brown jacket look deliberate as long as the two cloths are clearly different in colour or texture. Two navies that almost match look like a suit that lost its other half.

At lunch, or anything called smart casual

This is where people overthink it. Keep the trousers and change two things: the top and the shoes.

Swap the shirt for a fine merino or cotton knit, a polo with a proper collar, or, if the place is relaxed, a plain T-shirt in a heavier cotton. Swap the office shoes for loafers, clean leather trainers or suede boots. The crease and the cut of the trousers keep the outfit from sliding into weekend clothes, which is the whole point.

Texture helps. A knit, a suede shoe or an unstructured jacket softens a sharp worsted trouser without fighting it. Flannel trousers are at their best here, especially in autumn and winter.

In the evening

For dinner or an event, go darker and add a little shine somewhere. Black or midnight navy trousers are the base. Then choose one of these:

• a silk or satin shirt or top,
• a velvet or dark wool jacket,
• polished shoes, or a heel with some presence.

One is enough. Three at once starts to look like a costume.

If the event is formal, proper evening trousers differ from day trousers in small ways. They have no belt loops, they usually carry a braid or satin stripe down the outside seam, and they’re cut to be worn with braces or side adjusters. A plain black wool trouser with a clean hem and no belt loops gets you most of the way at anything short of black tie.

Watch the hem in the evening. If you change into a higher heel or a slimmer shoe, the trousers will sit differently. Trousers that will be worn with heels are best hemmed for the heel, so check before you leave that the back of the hem isn’t dragging on the floor.

Small things that get a pair through the day

A long day in one pair of trousers is mostly a matter of care.

• Empty the pockets. A phone in a front pocket spoils the line of any trouser, and keys wear holes in the pocket bags.
• Between wearings, hang them by the hem from a clamp hanger, or fold them along the crease over a wide bar. Wool recovers overnight if it’s allowed to hang.
• Keep a lint brush at work. Dark wool picks up everything.
• If the knees crease badly after a long sit, a few minutes of steam takes most of it out.

How to tell a pair will work

Before you buy, picture the trousers in three places: a meeting, a lunch and a dinner. If you can name the shoes and the top for each one without buying anything else, the pair has earned its place. If it only works with one jacket and one pair of shoes, it’s half of a suit, and you should treat it as one.