Sizing and fit
How do you measure a T-shirt to check the size?
Short answer
Lay a shirt that already fits flat on a table, smooth out the wrinkles, and measure straight across from armpit seam to armpit seam. Double that number for the chest. Then measure from the centre of the collar seam straight down to the hem for the length. Compare both against the listing's measurements.
Measuring a garment beats measuring a body, because listings quote garment measurements. Measuring a child's chest and then trying to guess how much ease to add introduces an error you do not need to make.
Two numbers do almost all the work. Chest determines whether it fits; length determines whether it looks right. Sleeve length matters far less on a T-shirt than people expect.
Where a listing gives no measurements at all, that is itself information. Established licensees almost always publish them, and their absence usually indicates a seller working from a generic blank.
- Use a shirt that fits now, not one bought to grow into.
- Measure flat and unstretched — pulling the fabric adds an inch that does not exist.
- Armpit to armpit, doubled, is the chest. Collar seam to hem is the length.
- Allow two to four inches over the body measurement for comfortable ease.
- If the listing and the chart disagree, trust the listing.
Published measurements to check yours against
Chest is measured flat across the shirt, so double it to get the way round. Body length runs from the high point of the shoulder to the hem.
Youth sizes, chest measured flat
If your shirt measures well outside these, you are probably measuring at the wrong point — chest width is taken an inch below the armhole, not at the widest part of the sleeve.
| Blank | Labelled | Chest, flat | Body length |
|---|---|---|---|
| Gildan 2000B | M (10-12) | 18 in | 23½ in |
| Gildan 64000B | M (10-12) | 17 in | 22 in |
| Hanes 5450 | M | 17 in | 23 in |
| Next Level 3310 | M (8) | 17 in | 22 in |
| Bella+Canvas 3001Y | M (10-12) | 16¼ in | 22⅛ in |
Across these blanks, the chest ranges from 16¼ to 18 in across — 1¾ in of difference, or 3½ in the whole way round, and the body runs 22 to 23½ in long.
Where these come from: each manufacturer's own published spec sheet, read on September 29, 2026 — Gildan 2000B, Gildan 64000B, Hanes 5450, Next Level 3310, Bella+Canvas 3001Y. Manufacturers allow a tolerance on every measurement, so an individual shirt can differ by up to an inch. We have not measured these shirts ourselves.
More detail: US T-Shirt Size Guide: Toddler to 3XL covers this subject in full.
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