Please measure yourself around the stomach where the belt is going to sit (belly button is usually the best place to measure). Please DO NOT use your trouser size. This will often be different; especially for anyone with trouser size over 34". All sizing is in inches ("), you can convert from cm to inches (if you only have cm on your tape) by dividing your cm length by 2.54 (use your phone calculator if you're not good at complex maths!). This will give you the size in inches.
Please note: Our sizing for weightlifting belts and powerlifting belts can differ (i.e. a small weightlifting belt won't necessarily be the same as a small powerlifting belt). They can be similar (the overall belt lengths can often be similar) but the holes are in different places so the size ranges differ.
If in doubt please ask!