A heavyweight t-shirt is a shirt above a certain fabric weight. That is the definition. The weight is what you are actually talking about when you call something heavyweight. Not the cut, not the brand, not the price.
Here is what the number means and why it matters if you are having one printed.
The weight
Fabric weight is measured in grams per square meter, or GSM. A standard t-shirt runs at 140 to 160 GSM. You can feel the difference between that and nothing, but it is thin. Light enough to see through on white.
Heavyweight starts at roughly 180 GSM and goes up. Some shirts sit at 200 GSM. Some go to 230 or 240. At 200 GSM and above, the shirt is fully opaque, holds its shape out of the dryer, and does not move when you put it on.
If you see “6 oz” or “6.5 oz” on a blank, that is the American measurement for the same thing. 180 GSM is about 5.3 oz. 200 GSM is around 5.9 oz. Anything over 6 oz is solid.
Why it matters for printing
For custom printing, fabric weight changes the result in two ways.
First, opacity. On a thin shirt, ink does not have a solid surface to sit on. The white you print reads as off-white because light comes through from the back. On a heavyweight garment the contrast is correct. White reads white and colors read saturated. The difference is visible from ten feet away.
Second, heat stability. During curing, the shirt runs through a heat tunnel at around 300°F. Thin fabric can shift and pucker under that heat. A heavier shirt holds flat and comes through the other side with a clean print. Less chance of cracked ink or misaligned edges.
How it feels
Weight alone does not tell you everything about feel. Two shirts at 200 GSM can feel completely different depending on how the cotton was spun.
Ring-spun cotton is softer because the spinning process aligns the fibers tightly. Combed ring-spun is softer still, because the short fibers are combed out before spinning. A 180 GSM combed ring-spun tee can feel softer than a 200 GSM open-end shirt.
Most blanks we stock are ring-spun and pre-shrunk. Pre-shrunk means the fabric was washed before cutting, which takes most of the shrinkage out before the shirt reaches you. A shirt that shrinks 10% after printing is a problem. Pre-shrunk brings that down to under 5%.
The fit
Heavyweight blanks tend to run a true size. They do not stretch or drape the same way a thin athletic tee does. The fabric has more structure so the shirt holds its shape. Boxy if it is cut boxy, fitted if it is cut fitted.
If you are going oversized intentionally, a heavyweight blank read as oversized on purpose. If you are going standard fit, it reads as a shirt that was made properly. Either way the weight supports the intention.
What to order
For a screen-printed t-shirt that you want to look good and hold up: start at 180 GSM minimum. 200 GSM is better. If you are doing a large print on a white or light shirt, 200 GSM is where the colors stay correct.
Send us your design and the quantity and we will confirm the blank that fits the print.
For puff print or any dimensional technique, the same rule applies. Heavier is better. We cover what that looks like on a hoodie on the puff print hoodie page.
By Michael Monfared, ThreadGhost