Understanding Belt Sizing
This calculator converts a waist or pant size into the belt size you should buy, using the sizing convention followed by most belt and apparel brands: a belt runs about 2 inches longer than the pant or waist size it fits. Because the belt sits over the pants at the waistband and the buckle itself takes up a little length, a size-34 pant typically calls for a size-36 belt.
The formula
Belt size (inches) = Waist or pant size (inches) + 2
Most belts are manufactured only in even-numbered sizes (30, 32, 34, 36, and so on), so this calculator rounds the result up to the next even number by default. Switch the rounding option to "Exact calculated size" to see the raw, unrounded figure — useful when comparing against a brand that sells odd sizes or half-sizes.
Measuring your waist
If you already know your pant size, you can enter it directly — it is normally close enough to your waist for sizing a belt. For a direct measurement, wrap a soft tape measure around your body at the height your pants sit when worn (through the belt loops), not necessarily your natural waistline, and read the value where the tape meets zero without pulling it tight.
Size categories
Alongside the numeric size, this tool maps the result to an approximate alpha size (S, M, L, and so on) using a common belt sizing chart. Brands vary slightly in where they draw these lines, so treat the category as a rough guide and check a specific manufacturer's chart when one is available.