Choose the finger: Decide which finger you want to wear the ring on. Keep in mind that fingers on your dominant hand may be slightly larger.

Time of day: Measure your finger at the end of the day when it's likely to be at its largest due to factors like temperature and activity.

Tools needed: You'll need a flexible measuring tape or a piece of string, a marker and a ruler.

Measure diameter: Wrap the measuring tape or string around the base of the finger where the ring will sit. Make sure it's snug but not too tight. Mark the point where the string or tape meets, then straighten it out and measure the length in millimetres from the end to the mark. This measurement is the diameter.

Measure circumference: Alternatively, if you have a ring that currently fits the finger well, you can measure the inside diameter of the ring and convert it to circumference. Divide the diameter by 3.14 (π) to get the circumference.

Check sizing chart: Once you have your measurement, compare it to a ring sizing chart. These charts usually have measurements in both millimetres and corresponding ring sizes. Keep in mind that different countries may use slightly different sizing systems.

Consider width: If you're choosing a wider ring, you might want to go up a half or full size for comfort.

Get a professional measurement: If you're unsure about measuring at home or if you're between sizes, it's a good idea to visit a jeweller who can provide an accurate measurement.