Like all companies sizing will vary and be based on measurements. Each cut and individual item will have its own sizing range based on the fit that it was designed to achieve.
Contrary to popular belief, there is no standardized USA sizing. So to say that you always wear a size L means very little.
In each listing you will find sizing ranges, varying from the beginning of the measurement to the very end. DO NOT purchase an item that measures 34-40″ for example and say that it was supposed to fit a 40″ waist. It is not. You must account for breathing room, the size of your hips that the item must slide over, whether you need to have a pouch for other endowments and how that will affect the fit.
For women we recommend to be closer to the end of the measurement range for string bikinis, for a sung fit. Allow the item enough spade to slide over your hips. For men, we recommend to be comfortably in the middle if getting a feminine or female cut. You can be closer to the end, if you are getting an item with a pouch however NOT at the very end of the range.
One size items are ONE SIZE, they do not come in other sizes and the range will be listed in each listing. I have made a short and silly video explaining the impact on sizing when men purchase women’s panties. (which we highly recommend trying)
In general if you are new, purchase ONE item and give it a whirl. You will always be able to come back and try more once you know what is right for you!