The beach onesies currently come in just one size. They fit anyone with a measurement of up to 40 inches. It looks like they have plenty of fabric but the trick is that you must be able to fit into the straps. Otherwise, the top would be as wide as the pants and would hang from your underarms like those people who wore barrels in old cartoons.
How to measure:
Take a tape measure and wrap it across your back at the bra line around to meet at the front. This is the fullest part of your bust. Make a note of this measurement. Please note that the band size of your bra is not the same as your bust measurement.
Next, measure around the fullest part of your hips and derriere. This is your hip measurement.
If both numbers are under 40 inches, the beach onesie is already sized for you. The straps are adjustable which keeps them from slipping down your arms but doesn’t help with the sizing.
Is your biggest number above a 40? Let me know! If there is enough interest I will make a second size.