US Ring Size Calculator and Chart

Circumference =   mm
Inner Diameter = mm


In the US and Canada, standard ring sizes range from 0 to about 18 with increments of 1/4 (0.25). A ring size of 0 corresponds to a circumference of about 36.55 mm, or a diameter of 11.63 mm. A ring size of 16 corresponds to a circumference of around 77.38 mm, or a diameter of 24.64 mm.

You can measure your ring size using the Ring Finger Sizing Tool, and then input the measurement into the calculator or look it up in the chart below. If your ring size is between two standard sizes, it's usually better to go with the higher of the two to ensure that your ring fits.

You can also use the calculator and chart for UK ring sizes. Note that a 1/4 US size increment is approximately equal to a 1/2 UK size increment, but the two sizing systems do not match up perfectly.

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