Most of the developer tees you collect for free are 140–160GSM cotton. They feel papery in the hand, go translucent in bright sun, twist along the side seams after a tumble-dry, and stretch into ovals at the neck within two months. GemZy tees are 240GSM — heavyweight, structured, opaque and built to keep their shape past the first hundred washes.
This is the long answer to "what is GSM" and the field-tested reason GemZy picked 240, written by the engineer who bought thirty sample blanks across five Bengaluru mills before signing a supplier.
Written by Venkatesh, founder of GemZy. Backend engineer by day; spent a quarter turning my flat into a t-shirt testing lab to pick the GemZy spec.
What GSM actually means
GSM stands for grams per square metre — the mass of one square metre of the fabric. It is the single most useful number on a t-shirt spec sheet because it captures three things at once: how much cotton is in the yarn, how tightly the knit is built, and how the finished garment will hang on a human body.
A higher GSM means a denser knit, more cotton fibre per square inch, and a fabric that drapes with weight instead of clinging to skin. A lower GSM means less material, more transparency, faster wear-through and a flatter, limper drape.
The fabric-weight chart, decoded
| GSM | Feel | Where you find it | Verdict for a daily-wear tee |
|---|---|---|---|
| 120–140 | Tissue-thin, translucent | Free hackathon tees, giveaway swag | Avoid. Wears through inside a season. |
| 160–180 | Light, soft, slightly see-through | Entry-level retail, fashion brand basics | Decent for layering, weak as a standalone |
| 200–220 | Substantial, opaque | "Premium" Indian DTC brands | Solid mid-range. Most buyers stop here. |
| 240+ | Heavyweight, structured | Tokyo and LA streetwear houses | The print-longevity sweet spot for cotton |
| 300+ | Sweatshirt-adjacent | Boxy heavy tees, workwear | Too warm for Indian climates outside winter |
The right number is the highest one your climate and use case will tolerate. For India that ceiling is around 240–260; past that you start trading wearability for spec-sheet bragging rights.
The thirty-blank test
Between January and March 2024 I bought roughly thirty sample tees from five mills around Tirupur and Bengaluru. Same size, similar cotton grade, GSMs ranging from 160 to 280. I wore each on a rotating schedule for two weeks, washed them on the same cycle, and rated them on five axes.
The gap between 200 and 240 was not subtle:
- Drape. A 240GSM tee falls in a clean rectangle from the shoulder. A 200GSM tee starts clinging to the stomach after a meal.
- Opacity. Even white 240GSM stays white-white in direct sun. White 180GSM goes pink-grey the moment a fan blows on it.
- Print durability. DTF and water-based screen prints bond harder into a denser knit — fewer micro-gaps in the fabric for the pigment to bridge. (We wash-tested the print methods separately, and the day-to-day wash-care routine is here.)
- Shape retention. Pre-shrunk 240GSM combed cotton kept its collar circle and side-seam alignment past 40 washes. The 160GSM samples stretched into ovals inside ten.
- Hand feel. This one is subjective, but every non-developer I handed a 240GSM tee to said "this feels expensive" before I told them the price.
Does 240GSM work in Indian summers?
This is the objection I hear most often, and it is fair. India is not Tokyo and a Bengaluru April is not a Daikanyama October.
The honest answer: 240GSM combed ringspun cotton is comfortable from October through May across most of India, and bearable through a Bengaluru or Bangalore summer because the city stays under 35°C most days. In peak Chennai, Delhi or Hyderabad summer — 40°C+, high humidity — a 180–200GSM tee is genuinely more wearable for outdoor use.
What you trade is longevity. A 180GSM tee is cooler in May and a rag by August. A 240GSM tee is slightly warmer in May and still on rotation three years later. For a tee that lives mostly in air-conditioned offices, co-working spaces and laundry rotation — which is the GemZy use case — 240 is the right call.
Why GSM alone is not enough
Two 240GSM tees can feel completely different. GSM tells you the weight of the fabric; it does not tell you:
- Yarn type — combed ringspun cotton feels smooth and dense; carded open-end cotton at the same GSM feels rougher and pills faster.
- Knit structure — single jersey, interlock and pique at the same GSM behave differently in drape and stretch.
- Pre-shrink treatment — an untreated tee can shrink 5–8% the first wash regardless of GSM.
- Stitch quality — twin-needle hems and shoulder taping decide whether a tee survives a tumble dryer or comes out twisted.
GemZy locks all four: 240GSM, combed ringspun, single jersey, pre-shrunk, twin-needle hemmed, shoulder-taped. GSM is the headline number; the rest is what makes the headline number worth paying for.
How to check GSM before you buy
Most Indian DTC brands publish GSM on the product page. When they do not, three field tests get you close:
- Hold the tee up to a window. Lower GSM lets through light at the shoulders and across the chest. 240+ stays opaque.
- Pinch and release. A heavyweight knit springs back into shape immediately. A light knit holds the crease for a beat.
- Weigh it. A men's medium 240GSM tee weighs roughly 210–230g on a kitchen scale. A 160GSM medium comes in around 140–160g.
If a brand will not tell you the GSM, that is the answer.
Frequently asked questions
What is the best GSM for a t-shirt? For daily wear in most Indian climates, 200–240GSM is the sweet spot — heavy enough to drape and hold prints, light enough for year-round use. Below 180 you sacrifice durability; above 260 you sacrifice summer wearability.
Is 240GSM too heavy for summer in India? Not for air-conditioned indoor use, which is most of a software engineer's day. For peak summer outdoor wear in 40°C+ cities a 180–200GSM tee is more comfortable. GemZy ships 240 because the use case is daily rotation, not a beach day.
Why do premium t-shirt brands use 240GSM cotton? Three reasons. The fabric drapes cleanly without clinging, it holds DTF and screen prints past 50 washes because the knit is dense, and it keeps its shape after dozens of cycles because the yarn has more fibre to spring back with.
Will a 240GSM cotton t-shirt shrink? A properly pre-shrunk 240GSM combed cotton tee shrinks under 2% across its life. An un-treated blank can lose 5–8% on the first wash. Always check whether the brand pre-shrinks.
Does higher GSM mean better quality? Up to a point. GSM is necessary but not sufficient — yarn type, knit structure, stitching and pre-shrink treatment matter just as much. A 240GSM combed ringspun pre-shrunk tee will outlast a 280GSM carded open-end tee at almost any price point.
If you want to put a 240GSM GemZy blank in your hand before deciding, message us on WhatsApp at +91 80730 88890 and we will ship a single tee. One feel test is worth a thousand spec-sheet arguments.
If you have ever pulled a free conference tee out of the wash and it looked like a dishrag, you already know the answer.
— Venkatesh, founder, GemZy