How Do You Measure Your Ring Size?

There are a few different ways you can measure your finger to get your ring size. Jameson Murphy/Shutterstock

Beyoncé is no fool. Her song "Single Ladies" ("If you liked it then you shoulda put a ring on it") basically tells single women to dump their men if they don't step up and propose with a ring. Her man, Jay-Z, did just that five months before the song debuted in 2008. The couple have been married ever since.

But how did Jay-Z know Beyoncé's ring size? He did, after all, propose with a whopping 18 carat emerald cut diamond stunner.

If you're ready to put a ring on it — even if it's not 18 carats — here's how to assure it's a successful fit. Choreographed Sasha Fierce dance routine not required.

How Rings (and Fingers) Are Measured

Just like clothing, ring sizes vary from country to country. And of course, every person is different, so it's hard to nail down a true average finger size. But for general purposes, the average U.S. ring size for women is between 5 and 7. For men, it's between 9 and 10.

Jewelers use a scale of numbers that convert to the circumference of your finger in millimeters. That means a ring size 5 fits a finger with an inside circumference of about 49 millimeters, and a ring inside diameter of about 15.7 millimeters. For more ring size conversions, check out this handy chart.

How to Measure for Ring Size

In theory, a flexible tape measure and the information above could help you buy the right ring size, but it's still a little too unreliable. So to find the right ring size, here are a few other options to consider.

Download a paper ring sizer. However, this may not be the most accurate option since printer settings can vary.
Wrap a piece of string, floss, thread — you get the idea— around the base of your finger, marking where it first overlaps. Unroll and lay it next to a ruler and note the length in millimeters. (This also may not be ideal if you're trying to get someone else's ring size for a surprise gift.)
If you plan on regular ring shopping, either for multiple fingers or multiple people, invest a few bucks in a set of ring sizers. They're relatively inexpensive online; you can also buy from an online jeweler like manlybands.com that reimburses the cost when you make a ring purchase.
If it's truly meant to be a surprise, then it can be difficult to get a true sizing of someone else's finger. Your best bet is to find a ring they already wear and measure the inside diameter. You can try the "secret test" at the bottom of this printable from Zales, or better yet, take their ring to a jeweler and have the size professionally confirmed.

Other Considerations

While getting the base measurement is primary, there are a couple more things to consider when you're trying to determine ring size.

Most notably, measure your knuckles, as well, as you may need to size up. You want the ring to have slight resistance going over the knuckle with a twisting motion. If the ring is too big, it could go flying off.
Consider your preferred style. A wider ring band can have a different fit than a standard size band.
Consider your preferred fit. Do you like a snug or a little looser fit? Many jewelers sell comfort fit rings that give a little extra room.