As a general rule, the right size leather belt for you is one size (or two inches) longer than your waistline. When you’re shopping for a comfortable, secure leather belt, start by determining your waist size by measuring yourself or checking the label on a comfortable pair of your pants or shorts. For most good-quality belts, this should mean that you can comfortably fasten the belt in the middle loop. When dressed for a formal occasion, perfect for a black leather belt, a short tail of no more than three inches is style-appropriate.