Somewhere in the last decade, fit names got out of hand. Athletic, tailored, engineered, performance, dynamic, streamlined. None of them are defined, none of them are comparable between brands, and most of them exist so that a garment can be described as fitted without saying tight.
We use two: close and regular. Here is what each one means and when you want it.
Close
Close means the garment is cut with no deliberate ease. It follows the body without compressing it. You should be able to pinch a little fabric at the chest or the thigh, but not a handful.
You want close in three situations. First, under another layer, because loose fabric under a shell bunches at the shoulder and stays bunched. Second, on efforts over about an hour, because loose fabric moves, and fabric that moves against damp skin is what produces a rub at the fifteen kilometre mark. Third, anywhere the garment needs to stay put on its own: a bra, a tight, a base layer.
The trap with close fit is buying it in the size you wear for a t-shirt. A close-fit running tee in your normal size will feel snug in a fitting room and correct at kilometre eight.
Regular
Regular means there is real room through the chest and the waist, cut to be worn on its own or over something else. It is what you want for the gym, where you are moving in every direction rather than one, and for anything you will still be wearing afterwards.
Regular does not mean oversized. There is enough room to layer a base underneath and no more. A wind shell cut regular has to go over a hoodie without pulling at the shoulder seam, so it is the roomiest thing in the range.
Between two sizes
The general rule: size up in tops, size down in bottoms.
A top one size up gains room in the chest, which is usually welcome, and roughly two centimetres in length, which is rarely a problem. The failure mode of a top that is slightly too big is that it looks slightly too big. The failure mode of one that is slightly too small is that you stop wearing it.
A bottom one size down keeps the waistband under tension, which is the only thing holding it up. A drawcord will pull a waistband in a little, but it will not fix a waistband that is a full size too wide, and a bonded waistband has no drawcord at all. Bottoms fail upwards, not downwards.
The measurement that actually decides it
For bottoms, the inseam matters more than the size letter, and it is the one measurement you can check against something you already own. Lay a pair you like flat, measure from the crotch seam straight down to the hem, and compare that to the inseam printed on the product page. A five inch short and a seven inch short in the same size are two different garments.
When the garment runs small
Sometimes a piece just runs small or large against the chart. When it does, that belongs on the product page in plain language, not buried in the reviews for you to find. If you order something from us and it runs off the chart, tell us, and it goes on the page.