I stopped buying my actual size in tops and jackets years ago and it changed how my clothes look more than any single purchase did. So let me argue for it properly, because said badly it sounds like advice to swim in your clothes.

The point is not volume. The point is that a garment sitting slightly away from the body drapes, and drape is most of what reads as expensive. When cloth is under tension across your chest or your upper arm, the eye sees the tension first, and tension reads as a garment that does not fit no matter what the label says.

There is also a comfort argument that I think is underrated. Clothes that touch you everywhere are clothes you are aware of all day, and you can see that awareness in how someone stands.

Below, the three categories where going up genuinely works, and I will also tell you where it does not.

Shirts are where sizing up is nearly always right. Take the larger size and look at three things.

The shoulder seam should sit at or just past the edge of your shoulder. Past is fine and modern. Well past and the whole sleeve head collapses, which reads as a mistake rather than a choice. The chest should have enough room that you can see a shadow between the placket and you when you stand normally. And the sleeve should be long enough to push up and stay up, which means it needs both length and a cuff with some structure.

Fabric decides whether the extra room looks deliberate. Poplin, oxford cloth and heavier silk hold a shape and fall in a clean line. Very thin, very drapey fabric in a large size clings in the wrong places and looks like it belongs to somebody else.

The exception: a shirt you intend to wear tucked and belted, where a huge body just creates bulk at the waist.

Knitwear is the other clear yes, with one caveat: knit stretches and grows, so a size up in a heavy knit can become two sizes up after a season of wear. Buy the larger size in fine gauge and be more careful in chunky.

Check the sleeve length against your wrist rather than your hand, check that the ribbing at the hem is not so tight that it pulls the body into a balloon, and check the neck. A neck that gapes on a size up is the one thing you cannot fix.

Jackets and blazers are more complicated and worth it. Going up gives you the shoulder line that makes tailoring look current, and it lets you wear a jumper underneath, which is the whole point of a jacket in winter. What you must check is the sleeve, because a long sleeve on a big jacket is the single fastest way to look lost in it. Sleeves are cheap to shorten. Shoulders are not.

Where sizing up is wrong: trousers, skirts and anything cut on the bias.