For the best fit, take an existing belt and measure from the leather at the buckle end to the hole you use the most. Then round up to the nearest available measurement (usually an even number). If you don't have an existing belt take your waist size and add 2-3 inches to get your size.
Do Not: Do Not measure the waist band of your pants.
Do: If you don't have a belt to measure, add 2-3 inches to your waist size.