You don't need a trip to the jeweler to find your ring size — a piece of string, a ruler, and five minutes will get you very close. Here are five reliable ways to measure ring size at home, including how to secretly size a partner's finger for a surprise proposal.
Before you start: 3 quick rules
- Measure at the end of the day. Fingers are smallest in the morning and largest in the evening.
- Don't measure cold hands. Cold fingers shrink and give a size that's too small.
- Mind the knuckle. The ring must slide over your knuckle, so measure the widest point if your knuckle is larger than the base.
Method 1: The string or paper method (easiest)
- Wrap a strip of paper or string around the base of your finger.
- Mark where it overlaps with a pen.
- Measure the marked length against a ruler in millimetres — that's your finger circumference.
- Enter it into our ring size calculator or match it on the ring size chart.
Method 2: Use a ring that already fits
Take a ring that fits the correct finger and measure the inside diameter straight across, edge to edge, in millimetres. Then look up that diameter on the chart. This is often the most accurate home method.
Method 3: Printable ring sizer
Print a paper ring sizer at 100% scale (don't let your printer "fit to page"), check it against a ruler, then wrap it around your finger or place an existing ring over the printed circles. Always verify the print scale with a ruler first, or the sizes will be off.
Method 4: The credit-card calibration trick
On-screen "ring sizer" tools are only accurate if the screen is calibrated, because every screen has a different pixel density. Calibrate using a credit card — every card is exactly 85.6 mm wide — so you have a real-world reference before measuring. If a tool doesn't let you calibrate, treat its result as a rough guide only.
Method 5: How to find their ring size without them knowing
Planning a surprise proposal? Try these stealth methods:
- Borrow a ring they already wear on the ring finger, trace its inside circle on paper, or press it into a bar of soap, then measure the inside diameter.
- Ask a close friend or family member who might know or can ask casually.
- Compare to your own finger — slip their ring onto your finger and mark how far it goes; a jeweler can size from that.
When in doubt, size slightly larger — a ring can be resized down more easily than the surprise can be saved if it won't fit at all.
Convert your measurement to a size
Once you have a millimetre measurement, the rest is easy: use the Ring Size Calculator to convert it, or read it off the full Ring Size Chart for US, UK, Europe, Japan and India sizes.