There are a few ways to go about this. Whichever method you use, be as precise as possible, when it comes to ring sizes, small amounts matter.

Please note, if the ring you're measuring isn't the same width as the one you're ordering, make sure you check out the DOES THE WIDTH AFFECT THE SIZE section of our In-depth Sizing Guide.

USING OUR Printable Ring Sizer: No special tools? Print out and follow our Printable Ring Sizer.

USING CALLIPERS: Make sure you measure to the nearest 0.1mm. The callipers below show an internal diameter of 16.5mm or US size 6 (UK L ½).

To convert your internal diameter to a ring size see our Ring Size Conversion Chart

USING A RING SIZING MANDREL: Make sure you measure to the edge of the ring, not the centre.

Measured to the edge, the ring below is sized US 6 (UK L ½) but measured to the centre it would be US 5¾ (UK L) AKA too small.

 USING A RULER: In our opinion, this isn't a very good idea, it's just too hard to be accurate enough.