Getting your ring size right is simple. The most accurate option is to use a jeweler or a plastic ring sizer, but you can also get a good at-home estimate with a flexible tape or string and a ruler.
Step 1: Measure the finger
Wrap a flexible measuring tape or a piece of string around the finger where the ring will sit. Mark where the ends meet.
Step 2: Measure the length
Lay the string flat and measure it with a ruler in millimeters. That measurement is your finger circumference. Then compare it with a ring size chart to find the closest size.
Step 3: Check the fit properly
Your ring should feel snug enough not to fall off, but loose enough to slide over your knuckle comfortably. If your knuckle is larger than the base of your finger, measure both and choose a size in between.
Step 4: If you already have a ring, use it
Pick a ring that already fits well and measure its inside diameter in millimeters. Match that measurement to a ring size chart. This is especially useful if you are buying as a gift.
Step 5: Measure at the right time
Measure at the end of the day, when your fingers are warm, and repeat the process a few times for a more reliable result. Finger size can change with temperature, humidity, and time of day.