Mens belt sizes.....yawn, yawn, yawn

[PersisFord]

I have decided to buy DH a belt. His current one measures 41 inches but says 31 inside it. The one I want to buy comes in sizes 32, 34, 36. What does this mean? Which do I buy?? I have been up all night with a teething baby and I do not need this kind of mental stimulation. I just want to order it so I can pick it up from waitrose tomorrow when I go for my free coffee. I'm so mumsnet!

Please help me. Don't make me take my screaming baby into an actual shop and measure the fucking belts!!