You do not need a jeweler to find your ring size. A piece of string, a ruler, or a ring you already own will get you there in about five minutes.

The four methods, from most to least accurate:

1. Use a dial ring sizer or order an inexpensive plastic one.
2. Measure a ring that already fits with a ruler. Make sure it is a ring worn on the same finger you intend to wear the new ring on.
3. Wrap string or dental floss around your finger and measure it.
4. Wrap a soft tape measure around your finger and read it directly.

Any of these methods will work, but the most reliable is the plastic sizer. The rest of this guide walks through each one, plus the small mistakes that throw a size off by a half size or more.

How do you measure ring size with string?

The string method is the classic at-home approach. You need string, thread, or dental floss, a pen, and a ruler.

1. Cut a piece of string about six inches long.
2. Wrap it around the base of the finger you will wear the ring on.
3. Keep it snug but comfortable. It should slide slightly, like a real ring.
4. Mark the exact point where the string overlaps.
5. Lay the string flat and measure to the mark in millimeters.

That measurement is your finger's circumference. A US size 7, for example, is about 54.4 mm around. To turn your number into an exact size, use our ring sizer and size table, which converts millimeters to every US and international size.

One warning: string stretches, and floss can dig in. If your number lands between two sizes, measure twice more and take the middle result.

How do you measure ring size with a tape measure?

A soft sewing tape measure skips the ruler step. Wrap it around the base of your finger, read the millimeter mark where it overlaps, and you have your circumference in one move.

If your tape only shows inches, that still works. A size 7 is about 2.14 inches around. Multiply inches by 25.4 to get millimeters, then convert with the size table.

Two tips make this method more accurate. First, measure at the end of the day, when your fingers are at their largest. Fingers are smallest in the cold morning and largest when warm. Second, if your knuckle is noticeably wider than the base of your finger, measure the knuckle too and pick a size between the two numbers. The ring needs to be large enough to slip over the knuckle, but not so large that it slips off the finger.

How do you find your ring size from a ring you already own?

This is the best method when you want to know your ring size without measuring your finger at all. It also works for sizing someone else, as long as you can borrow a ring they actually wear on the correct finger.

Take a ring that fits well and measure the distance straight across the inside of the band, edge to edge, in millimeters. That is the inside diameter. A US size 7 has an inside diameter of about 17.3 mm.

Even easier: hold the ring up to a calibrated on-screen circle and match it by eye. Our ring sizer page has a dial you calibrate with a bank card, so the circles on your screen are true to life. Match a ring you own to the circle and read your exact size, with no math involved.

Buying secretly for a partner? Borrowing a ring is the core of most stealth tactics. We cover the full playbook in our guide to finding her ring size without asking.

Can you print a ring sizer at home?

Yes. A printable ring sizer is a paper strip or a page of sized circles you print, cut out, and use like a jeweler's tool. It is more reliable than freehand string, because the sizes are pre-marked.

Printing has one trap: your printer must print at 100 percent scale. If the print dialog says “fit to page,” turn it off, or every circle will be slightly wrong. Most printable sizers include a credit card outline so you can check the scale before you trust it.

You can grab our free printable sizer on the same Foreverings sizer page linked above. If you would rather not gamble on printer settings, the page also lets you order a physical dial sizer for one dollar, and it comes with a $5 coupon toward your ring. That is the closest thing to a jeweler's fitting you can do from your couch.

Tips for a ring that actually fits

Getting the number is half the job. These fit rules cover the other half:

• Measure the exact finger. Your left and right hands differ by up to half a size. Measure the finger you intend to wear the ring on.
• Measure warm, not cold. Cold fingers shrink. Late afternoon at room temperature is the most honest reading.
• Between sizes? Go up. A slightly loose ring can spin on the base of the finger, but it is better to be slightly loose than too tight. A too-tight ring causes discomfort, and a stuck ring is a real problem. If a ring does get stuck, do not pull; there are safe ways to remove it.
• Wide bands run snug. Bands 6 mm and wider grip more skin. Consider a half size up for wide styles, common in men's tungsten rings.
• Half sizes exist for a reason. If a whole size flops and the next size down pinches, the half size between them is your size.

Ready to check your size?

Five minutes with any method above gets you a number you can trust. Confirm it against the interactive ring sizer, and you will never have to guess at checkout again. For international size systems and the full mm conversion table, the same page covers every standard, as documented in the ISO ring size standards.