The centre of shinfin
So in colder water, the fins fit with a wetsuit. Then, when the water is warmer, you can readjust the straps to wear them without a wetsuit. The fins still fit.
The straps go around the narrowest part of your leg, just above your ankle. So, please measure the circumference around this narrowest part whilst wearing your wetsuit. If this circumference is 20-40 cm (8-16 inches) then the standard straps supplied with the fins will fit you. If this circumference is larger than 40 cm (16 inches), then just select the option for longer straps when you order your fins.
If you prefer to measure your leg circumference without your wetsuit, then just add the following to your measurement to compensate. For a thin 3mm suit add 2 cm (1 inch). For a thick 8mm suit add 5 cm (2 inches).
See related faqs about why these fins keep fitting growing children and why you can share these fins with different sized people.
See all faqs about the adjustable fit of these fins.