Myth, all mediums are the same

Short answer: There is no shared standard for letter sizes. A medium from one brand can match a small or a large from another, so the letter alone does not tell you how a garment will fit.

Every brand has its own scale

The letter on the label is the brand's own choice, not an international norm. Each brand decides how many centimetres a medium should measure at the bust, waist and hips. Some cut a little larger, others a little smaller. So you may fit a medium in one brand and need a large in another. See bamboo slips.

Why there is no standard

Letter sizes are not regulated. Each brand cuts to its own scale and to the customers it serves. A brand that sells mostly in one country may adjust its sizes to the bodies there. Another brand picks a different model. The result is that the same letter covers different measurements depending on where you shop.

Centimetres are the only shared language

The measurements in the size guide can be compared across brands, the letters cannot. A centimetre is the same whichever brand made the garment. Once you know your own measurements, you can hold them up against any brand's guide. See bamboo socks, where the size follows your shoe size.

How to measure yourself

Use a soft tape measure and measure directly on the body in thin clothing. Measure the bust at the widest point, the waist at the narrowest and the hips at the widest. Keep the tape level and snug without pressing in. Write the numbers down so you have them ready next time you shop.

The cut shifts the size too

Even within one brand, the cut can change how a size fits. Slim fit and oversize in the same letter can fit completely differently, because they are cut with different amounts of room. An oversize medium can be wider than a slim fit large. Always check which cut a style has. See women's most popular.

The fabric plays a part

The fabric also affects how a size feels. A fabric with plenty of stretch gives and can sit close without feeling tight. A fabric with little stretch needs more room. When two styles in the same size feel different, the reason may be the fabric rather than the measurements.

When you fall between two sizes

If your measurements fall between two sizes, the choice depends on how you want the garment to fit. For a close fit, the smaller one may work, especially in a stretchy fabric. For more room, the larger one is the safe choice. Also think about whether the piece is worn under or over other clothes.

The conclusion

A medium is not a medium everywhere. The letter is the brand's choice, and cut and fabric can shift the size further. Measure yourself, compare with the centimetres in the size guide and check the cut before you choose. That way you get the right size more often.

Frequently asked questions

Is a medium the same everywhere

No. There is no shared standard, and a medium from one brand can match a small or a large from another brand.

What should you use instead

The centimetre measurements in the size guide. They can be compared across brands and countries, because a centimetre is always the same.

Why is there no standard

Because each brand cuts to its own scale and its own customers. Letter sizes are not regulated, so it is up to each brand.