Belt measuremnet instructions: Put on a pair of pants that fits well and represents what you plan to wear with the belt.Take a flexible measuring tape and thread it through the belt loops as you would a belt. Be sure you have the tape measure at the level on your waist or hips where you plan to wear the new belt. Note your waist/hip circumference. Add two inches to this measurement to determine your belt size. Option 2: measure your existing belt.