How to Measure Your Ring Size at Home (Without a Sizer)

Buying a ring as a gift or shopping online means you need to know the ring size, but most people do not own a jeweler sizer. This guide shows three accurate at-home methods, plus a conversion chart between mm, US, UK, and EU sizes.

Method 1: The String and Ruler Method

The most popular DIY method. Works for any finger.

1. Wrap a piece of string, dental floss, or a thin strip of paper around the base of your finger.
2. Mark the spot where the string meets itself.
3. Measure the marked length on a ruler in millimeters. This is your finger circumference.
4. Divide by π (3.14159) to get the inner diameter, or use the chart below.

Use our online millimeter ruler to measure the string if you do not have a physical ruler.

Method 2: Measure a Ring You Already Own

If you have an existing ring that fits the correct finger, this is the most accurate method.

1. Place the ring flat on a table.
2. Measure the inner diameter across the widest point in millimeters.
3. Look up the matching size in the chart below.

Our centimeter ruler online (switch to MM mode) is calibrated to actual size and works perfectly for this.

Method 3: The Printable Ring-Sizer Strip

Many jewelry sites print a paper strip you cut out and wrap around your finger. The catch: most home printers slightly scale the print, so the strip is rarely accurate. If you use this method, always verify the printed reference square against an actual credit card before trusting the result.

Ring Size Conversion Chart

Tips for Accurate Measurement

• Measure when your hands are warm. Cold fingers shrink; warm fingers swell. Aim for room temperature.
• Measure at the end of the day. Fingers are slightly larger in the afternoon than first thing in the morning.
• Measure the right finger. Engagement and wedding rings go on the ring finger (4th finger) of the left hand in most Western countries. Your dominant hand fingers are usually slightly larger than your non-dominant hand fingers.
• If between sizes, go up. A slightly loose ring can be resized; one too tight risks getting stuck.
• Wide bands need a larger size. A 6 mm wide band fits tighter than a 2 mm one. Go up half a size for wide bands.

When You Need a Jeweler

For expensive rings (engagement, heirloom, custom pieces), get a professional sizing at a jewelry store. They use precision metal sizers and can account for knuckle width versus base-of-finger width. The at-home methods above are great for casual rings and surprise gifts, but a real diamond is worth a free 60-second jeweler visit.