How to measure for the perfect fit

Gather Your Supplies. You'll need a piece of string and a ruler to get your measurement. We recommend using a string instead of trying to use a soft tape measure.

Measure. Wrap the string around your penis and behind your balls. Mark the string where it meets. You want the ring quite snug. You should be able to just fit a finger between your skin and the string when you're soft. And it should be comfortably tight when you're hard so that you can't fit in a finger. You may want to measure both soft and hard to double-check your size.

Determine Your Size. Measure the distance from the end of the string to the mark.  This is the circumference.  Use the handy table below to get your size.

Circumference Ring Diameter
13.0-14.5cm (5.0-5.75in) 40mm (~1.6in)
14.5-16.5cm (5.75-6.25in) 45mm (~1.8in)
16.5-18.0cm (6.25-7.0in) 50mm (~2.0in)
18.0-19.5cm (7.0-7.75in) 55mm (~2.2in)


If you're used to round cock rings, you should go down 5mm (~.2 in) from your round ring size. Our keyhole shape fits a bit looser than a round ring with the same diameter.

Tips For Measuring

  • Be sure to pull the string as tight as you'd like your ring to be.
  • If you're between sizes, go down to the smaller size.
  • Measure twice!  Due to the intimate nature of these rings, we can't accept returns or exchanges.