We recommend you have a think about the way you like to wear your underwear and then use our measurements below to guide you. You wear underwear all day, everyday so it's important to get the right fit. If you like a tight fit, go down a size and if you like it loose, go up as theres plenty of stretch to keep them snug.
With the retro, the fabric has no stretch so use the 'extended waist' measurements to gauge how much room you will have.