Armhole and shoulder line, two measurements that decide the fit

Short answer: Two measurements decide whether a T-shirt sits right on the upper body: the armhole and the shoulder line. The armhole measurement shows how much room the arm has, and the shoulder line shows whether the seam lies on the shoulder. Here is how to find both and what they mean for the fit.

What is the armhole

The armhole is the opening in the T-shirt where the sleeve sits. The armhole measurement is often used to compare how much room there is for the upper arm. A narrow armhole can pull when you lift your arm, while a wide one can feel loose under the arm.

How to measure the armhole on a T-shirt

Lay the T-shirt flat and measure from the shoulder seam down to the bottom of the armpit. The armhole measurement can also be the circumference of the whole opening, so check which method the chart uses. Always read how the measurement was taken before you compare it with yourself.

What is the shoulder line

The shoulder line is the seam where the sleeve meets the body at the shoulder. When the T-shirt fits, the seam lies on top of the shoulder point, where the shoulder curves down towards the arm. The shoulder line is one of the quickest signs of whether the size fits.

How the two measurements decide the fit

The shoulder line decides whether the top sits on the shoulder or falls over the arm. The armhole decides how freely the arm can move. Together they control whether the T-shirt feels close, roomy or relaxed and whether it looks good on the body.

When the shoulder seam sits too far out

If the seam hangs down over the upper arm, the T-shirt is probably too big or the cut is relaxed. That can be intended for a loose look. If you want a more fitted look, try one size down.

When the armhole is too narrow

If the T-shirt pulls under the arm when you lift it, the armhole is too narrow or the size too small. Try one size up and compare with the chart. You can also look at bamboo T-shirts for men, where the size chart shows several measurements.

Compare with a T-shirt you know

If you have a T-shirt that fits well, measure it and compare with the chart. It is the surest way to find out which size to choose. Remember to measure in the same place and in the same way, so the measurements can be compared.

Fabric and stretch matter

A soft fabric with stretch gives way, so a small armhole feels more forgiving. A stiff fabric does not. Bamboo fabric is soft and stretchy, but the size still has to fit. Also see socks for men and bamboo boxer briefs.

Frequently asked questions

How do I measure the armhole?

Lay the T-shirt flat and measure from the shoulder seam down to the bottom of the armpit, or measure the circumference of the opening. Check which method the size chart uses before you compare.

Where should the shoulder seam sit?

The seam should lie on top of the shoulder point, where the shoulder curves down towards the arm. If it hangs over the upper arm, the T-shirt is big or the cut is relaxed.

What if the sleeves pull?

Try one size up and compare with the size chart. If the T-shirt pulls under the arm, the armhole is too narrow or the size too small.