To know what is your belt size, measure your belt from the end of the belt on the buckle side to the hole you use.
In a perfect world, choosing your size online should be as easy as trying on in shop (minus the queues). Nothing is more frustrating than receiving an item that doesn't fit perfectly. When in doubt (and until technology exceeds our expectations with a custom sizing system), we recommend ordering multiple sizes if you're not sure. Once your order has arrived, you have 14 days to try on the items, choose the one that best suits your figure and return the others.