Why sizes differ from brand to brand
Short answer: There is no binding standard for clothing sizes. Each brand builds on its own measurement curve, which reflects its typical customer rather than a shared norm. That is why two garments with the same letter can fit quite differently.
No shared standard
A medium is not defined anywhere. Each brand decides how many centimetres it should be, so two mediums can differ by several centimetres in chest, waist and length. Guideline systems exist, but nobody is obliged to follow them. The letter only tells you where a garment sits in that brand's own range. See bamboo underwear for men.
The curve follows the customer
A brand that sells to a particular market adjusts its measurements to the average customer there. That is why sizes can feel different from country to country and from brand to brand. A brand with a younger audience may cut narrower, while another gives more room over the stomach and hips to suit its customers.
The cut plays a part
Even within one brand, two models in the same size can fit differently. A slim fit T-shirt and a regular fit T-shirt in medium do not share the same measurements, because they are drawn to sit differently. Always check which cut a model has, and look at the measurements for that model rather than the brand.
Fabric changes the feel
A fabric with stretch feels less tight than a firm fabric with exactly the same measurements. Jersey with elastane gives and follows the body, while a woven fabric holds its shape. Two garments with identical numbers in the chart can therefore feel like two different sizes once you put them on and move.
Why size charts exist
The chart in centimetres is the only thing that can really be compared across brands. The letter is just a label, but the numbers show how big the garment actually is. Check whether the chart lists body measurements or garment measurements, as they are two different things. Read more in our guide to briefs and underwear.
Measure something you own
The most reliable method is to measure a garment that already fits you well and compare the numbers directly with the chart. Lay it flat and measure the width under the arms and the length from shoulder to hem. That gives you a concrete starting point, so you do not have to guess from letters. See bamboo T-shirt for women.
Shrinkage counts too
A garment that shrinks a few percent can move almost half a size. On jersey it is mainly the length that changes. Wash according to the label, usually at 40 degrees, and be careful with the tumble dryer if the garment fitted exactly from the start. See washing and care.
Note your brands
Once you have found a size that fits with a particular brand, write it down together with the model name. Next time you can order with confidence, because you know how that brand cuts. It saves time and returns, especially when you shop online and cannot try things on first.
Use returns sensibly
If you are unsure, it can make sense to order one size, try it at home and exchange it if it does not fit. Try the garment on unwashed and keep the tags on until you are sure. That way you can exchange without hassle and end up with the size that suits your body.
Frequently asked questions
Why does medium not fit the same at every brand?
Because there is no binding standard. Each brand builds on its own measurement curve that reflects its typical customer, and the cut varies as well.
What can you rely on?
The size chart in centimetres. The letter is only a label, but the centimetre figures show how big the garment actually is and can be compared across brands.
How do I find my size most reliably?
Measure a garment that already fits you well, and compare the numbers with the chart for the model you are considering instead of going by the letter.
You can find the full range at Bamboo-Clothing.com.
