Tagged sizes lie. Measurements don't. The five numbers worth checking before you buy anything secondhand.
A medium from one label can be a large from another, and vintage sizing drifts further still. The only reliable way to know whether something will fit is to compare measurements against a garment you already own and like the fit of.
The five numbers
- Pit to pit — across the chest from one armpit seam to the other. Doubling it gives you the full chest circumference.
- Shoulder to shoulder — seam to seam across the back. The least forgiving measurement on structured pieces like tailoring and outerwear.
- Length — from the base of the collar straight down to the hem, following the back of the garment.
- Sleeve — from the shoulder seam to the cuff. On drop-shoulder cuts, measure from the collar instead and say so.
- Waist and inseam — for trousers, waist flat across the top edge, inseam from crotch seam to hem.
Compare, don't guess
Pick the piece in your wardrobe that fits how you want this one to fit. Measure it the same way and note the numbers. From then on you are comparing like with like instead of trusting a letter on a tag.
If a listing has no measurements, ask. A seller who knows their inventory will have them or will take them for you. Sellers who won't are telling you something.
Watch for shrinkage and wear
Older cotton and wool that has been washed repeatedly can sit noticeably smaller than it did new, especially in length. Conversely, knitwear and leather relax with wear. Treat the measurements as the truth about the garment today, not what the size tag claimed when it was made.