What GSM Actually Means
, 2 min reading time
GSM is grams per square metre — the one honest number in clothing. What 180, 250, and 310GSM actually feel like, explained with the shirts we make.
Every Obrava product page leads with a number: 235GSM. 280GSM. 310GSM. It is the most honest spec in clothing, and almost nobody explains it.
GSM, defined
GSM is grams per square metre — the weight of one square metre of fabric, on a scale. That's the whole definition. No marketing lives inside it. A higher number means more cotton in every inch: thicker hand, more structure, more opacity.
The scale, with reference points
- 120–160GSM — promotional tees and undershirts. Semi-sheer, and the hem curls after a month of washes.
- 160–200GSM — the standard. Most mall and fast-fashion tees live here. Fine. Forgettable.
- 200–250GSM — where "heavyweight" honestly begins. The shirt holds its shape on its own.
- 250–320GSM — true heavyweight. Boxy silhouettes work at this weight because the fabric can stand, not cling.
- 320GSM and up — tee territory ends and fleece begins. Hoodies and sweats live here. A 420GSM hoodie carries roughly triple the fabric of a mall tee.
Why weight changes everything
Weight decides how a shirt hangs: light fabric clings and creases, heavy fabric falls straight and holds a silhouette. It decides opacity — no undershirt logic. And it decides lifespan, because more fibre survives more washes. A heavyweight tee fades and softens with age. A light tee warps and thins.
What GSM doesn't tell you
Weight is necessary, not sufficient. Yarn quality matters: 40S combed cotton at 235g wears smoother than coarse yarn at the same weight. Knit density and finish — a sunfade, a snow wash, hand-distressing — change how identical weights feel. GSM tells you how much fabric you're getting. It doesn't tell you how good the fabric is. Read both specs.
The ladder, in shirts we actually make
- 200GSM — Core Baby Tee: cropped and fitted, the lightest weight we cut.
- 235GSM — Neo Blade Oversized Tee: 40S combed cotton, proof that yarn quality carries the mid-weights.
- 250GSM — Kanji Dragon Sunfade Tee: hand-scrunched finish on a true heavyweight base.
- 280GSM — Heavyweight Rib Tank and Kanji Dragon Cropped Tank: structure without sleeves.
- 310GSM — Kanji Longevity Tee: the heaviest tee we make.
- 420GSM — Dystopian Zip Hoodie and Shinsei Sun Fade Hoodie: fleece weight, built for years.
How to check before you buy
Look for the number in the product specs. If a listing says "thick" or "quality cotton" but won't publish a weight, that is the answer.
Weight is the spec. Everything else is the mark. Start with Core, Kanji Dragon, or Shinsei.