You should measure yourself correctly because our clothes should fit well to the body. Size is a basic thing when buying clothes.
You do not want to wear too large pants or too-tight dress! That will not look interesting.
It's best to measure yourself with a tailor's tape measure. Do not add or subtract centimetres. Actual measurements are needed for the garment to fit correctly.
The sizes might be a little different depending on the type of material. Datex and 3D materials