For the best fit just buy one size larger than your waist for regular use and 2 sizes larger if you will be carrying items on the belt.
So for example, if you are a size 36 waist buy a 38 belt for regular use or a 40 for carrying use. If you are in between sizes round up. We do have free exchanges if needed so no worries if you need a different size.
If you want to measure a belt you have measure from where the buckle meets the leather to the hole you are wearing the belt in comfortably. It does not matter where that hole is. Your new Hanks Belt will fit in the center hole using that measurement.
On each belt page then click on the Sizing Chart tab and there is a chart showing the measurement to the center hole of the belt. Compare your measurement to that and order that size. If you are in-between sizes then round up.