Hmmh, not sure what you are asking. If you mean the actual measurement of the belt compared to your waist size, then get it the same. Based on conversations I have had with some belt makers, they size the belt to be whatever waist size you specify when buckled at the center hole. This gives you the ability to add or lose weight without having to buy a new belt.

So when I ordered a 42" belt, it fit at 42" when buckled on the center hole, which give me at least 1", and almost 2", of adjustment either way.