Size & Fit Guide
Every tee we make has its own personality — and its own fit. Here's everything you need to get the size right on the first try, whether you're treating yourself or surprising your favorite scientist. No PhD required.
The 60-second fit check
The most reliable method, backed by rigorous peer review (our customers): grab a shirt you already own and love, lay it flat, and measure it. Then compare with the charts below. Done — that's the whole experiment.
How to measure
Length — from the highest point of the shoulder straight down to the bottom hem.
Chest width — across (not around) the chest, one inch below the armhole, with the shirt laid flat.
All measurements below are of the garment laid flat, straight from the manufacturers' spec sheets. Allow a manufacturing tolerance of about ±1 inch — even lab equipment has error bars.
Classic T-Shirts
Our workhorse. Relaxed unisex fit, true to size — if you normally wear an M, order an M. 100% ring-spun cotton, pre-shrunk.
| Size | Chest width | Length |
|---|---|---|
| S | 18″ / 46 cm | 28″ / 71 cm |
| M | 20″ / 51 cm | 29.3″ / 74 cm |
| L | 22″ / 56 cm | 30.3″ / 77 cm |
| XL | 24″ / 61 cm | 31.3″ / 80 cm |
| 2XL | 26″ / 66 cm | 32.5″ / 83 cm |
| 3XL | 28″ / 71 cm | 33.5″ / 85 cm |
V-Neck T-Shirts
Retail fit: cut a touch slimmer and about half an inch shorter than our classic tee. Between sizes, or just prefer more room? Size up. Unisex — the V flatters everyone.
| Size | Chest width | Length |
|---|---|---|
| S | 18″ / 46 cm | 27¾″ / 70 cm |
| M | 20″ / 51 cm | 28¾″ / 73 cm |
| L | 22″ / 56 cm | 29¾″ / 76 cm |
| XL | 24″ / 61 cm | 30¾″ / 78 cm |
| 2XL | 26″ / 66 cm | 31¾″ / 81 cm |
Premium T-Shirts
Our premium heavyweight tee. Garment-dyed and soft-washed, with a relaxed, slightly boxy cut — roomier through the body, true to size. Because each piece is dyed after sewing, measurements vary a little more than usual: that's the charm, not a defect.
| Size | Chest width | Length |
|---|---|---|
| S | 18¼″ / 46 cm | 26⅝″ / 68 cm |
| M | 20¼″ / 51 cm | 28″ / 71 cm |
| L | 22″ / 56 cm | 29⅜″ / 75 cm |
| XL | 24″ / 61 cm | 30¾″ / 78 cm |
| 2XL | 26″ / 66 cm | 31⅝″ / 80 cm |
| 3XL | 27¾″ / 70 cm | 32½″ / 83 cm |
| 4XL | 29¾″ / 76 cm | 33½″ / 85 cm |
Sweatshirts & Hoodies
Cozy Heavy Blend™ fleece (50% cotton / 50% polyester, 8 oz) with a relaxed unisex fit — true to size, with room to layer over a tee. The crewneck sweatshirt and the hoodie share the same measurements, so one chart covers both.
| Size | Chest width | Length |
|---|---|---|
| S | 20″ / 51 cm | 27″ / 69 cm |
| M | 22″ / 56 cm | 28″ / 71 cm |
| L | 24″ / 61 cm | 29″ / 74 cm |
| XL | 26″ / 66 cm | 30″ / 76 cm |
| 2XL | 28″ / 71 cm | 31″ / 79 cm |
Buying a gift?
You're in good company — most of our tees are gifts for a favorite scientist. Three tips from the field:
- Sneak into their closet. Find a tee they actually wear (not the conference freebie at the bottom of the drawer), measure it flat, and match it to the charts above.
- When in doubt, size up. A slightly relaxed tee gets worn; a tight one stays in the drawer with the freebie.
- Still unsure? Our classic tee is true to size — if you know their usual size, order exactly that.
And if the size isn't right, our 30-day guarantee has you covered — get in touch and we'll sort out an exchange. Fewer than 1% of customers ever need it, but it's there.