Stand straight with feet shoulder-width apart
Relax your abdomen and breathe normally
Locate your waist: the narrowest point between your bottom rib and hip bones
Use a flexible measuring tape
Wrap the tape around your waist level, keeping it parallel to the floor
Ensure the tape is snug but not compressing your skin
Make sure the tape is level and not twisted
Read the measurement at the end of a normal breath
Record the number in inches or centimeters
Measure twice and use the consistent result
Repeat at the same time of day for tracking changes (optional)