You can easily find your size by measuring your hips with a tape measure. The hip measurement is the measurement taken from the most protruding part of the buttocks while in a natural, upright posture. It is best to be naked when measuring.
Feet should not be touching each other while standing during measuring. They should naturally stand next to each other. When measuring, you should keep the tape measure parallel to the ground. You should not tighten the tape measure too much or leave it loose. You can measure your hips yourself in front of a full-length mirror or get help from someone.