To work out your belt size, please make sure to take measurements as described below and don't just reference the size of your pants.
If purchasing for yourself, you can take the measurement by threading a measuring tape through the loop of your pants/bottoms to determine the size (as long as this corresponds to where most of your pants sit). The measurement should be taken wearing clothes as a belt is normally worn with clothes...
Alternatively, and in the case of purchasing a belt for somebody else, it is simplest to take measurements off an old belt you/they currently wear.
Go to the end of the buckle and take the measurement from just on the inside of this buckle end (to account for buckle hardware thickness differences).
Then measure to the hole you/they mostly wear it at. You'll be able to tell as the hole will be the most worn.
The measurement you get from your/their belt will then correlate to the measurement from the inside of the end of our buckle to the middle hole in our belt. Thus giving you some room to move if your pants sit higher, or lower, you wear more layers, or you gain or lose some weight over time. There are five holes in total on our belts.
Note as a guide, your belt measurement in inches is usually a few sizes larger than your pant size, so be sure to take this accurately as belts made-to-order cannot be returned for an incorrect measurement.