Measure a shirt you already like

The letter on the label is not a measurement. A medium from one brand and a medium from another can differ by several centimetres across the chest, which is the difference between a shirt that drapes and one that clings.

There's one number that resolves it, and it isn't a measurement of you.

What's the number?

Pit to pit: the flat width of a shirt across the chest, from one armpit seam to the other.

Take a shirt you already own and like the fit of, lay it flat without stretching it, and measure straight across just below the sleeve seams. That figure is the single best predictor of how another shirt will feel, because it's measuring the same thing on both garments.

Everything else about a t-shirt is preference. This one is arithmetic.

Why not just measure my chest?

Because a garment isn't the same size as the body inside it, and the gap between them is the whole design.

Your chest measurement tells you nothing about how much room a particular cut is supposed to leave. A close-fitting shirt is drawn to sit near the body; a relaxed one is drawn with several centimetres of ease built in. Two shirts that fit the same person perfectly well can differ substantially across the chest, and neither is wrong.

Measuring a garment you already like skips the guesswork entirely — you're not estimating the ease, you're copying it from something that already works.

How do I compare my number to a chart?

Carefully, because charts don't all mean the same thing by "chest".

Some list the full circumference — what goes around the body — and some list the flat width, which is half of that. The two differ by a factor of two, and mixing them up is the single most common sizing mistake there is. Check which one you're reading before comparing anything to it, then match your pit-to-pit figure to the right column.

If you land between two rows, the smaller one gives a closer fit and the larger one gives the drape. That's a choice about shape, not a fitting error.

Does a recommended height and weight help?

It's a starting point, not the answer.

Where a chart publishes body recommendations, they're genuinely useful if you have nothing else to go on — and good enough to buy for somebody else. But two people at the same height and weight are shaped differently, and no chart can know that.

Use the recommendation when you have no shirt to measure. Use the tape when you do.

Does the cut change the answer?

Not the number, but definitely the feel.

The same measured chest can hang closer or looser depending on how the garment is drawn. So the size you pick doesn't move; what changes is how it sits. Which means the decision that actually matters isn't the letter, it's which cut you're choosing — and people who order a size up "because it's relaxed" end up with a long shirt, because the width they wanted was already in the pattern.

What if it's a gift and I can't measure their shirt?

Ask what size they usually wear, or work from the body recommendation.

For a relaxed cut their usual size is nearly always right, because the roominess is in the pattern rather than achieved by rounding up. The failure mode with gifts is buying a size up to be safe, which produces a garment that's too long rather than one that's comfortably wide.

What about the length?

It's the measurement people notice most and check least.

If length matters to you — under a jacket, tucked, or if you're particularly tall or short — measure your own shirt from the highest point of the shoulder to the hem and compare it to the chart's length column. That's a second twenty-second measurement, and it prevents the most common source of disappointment.

How do I order?

Pick the design at JustOG, choose the garment and size, drag the crop frame, and see it composited on the real thing before ordering. It's made to order and shipped.

Designs other people have published are in the shop.

The label is a letter. The tape measure is a fact.