It generally depends on the tightness of the elastic band used. It is best to wrap the elastic band around your waist, not too tight, just be comfortable. After the test, don't hold elastic belt, and check whether elastic belt can easily cross his hips. Take off the elastic band. Don't forget to make a mark when you take off the pin. Don't forget the sewing head (about 3cm) when cutting. Or you can subtract 5cm from the waist circumference.

reach

10cm

To calculate the length of the elastic band. (Of course, it's better to try. )