A Guide for How to Measure Your Ring Size at Home

With the internet offering us access to every corner of the globe, we rarely need to leave the comfort of our own homes to run errands, exercise, get food—basically, do anything. So the same should be true when it comes to measuring your ring size before ordering from the best jewelry stores or hinting to your boyfriend about some unique engagement rings you’ve had your eye on. You could go to a jeweler, but that doesn’t really fit with the whole doing-it-all-from-my-couch thing you’ve got going on. (It also ruins the subtlety of accidentally leaving a browser open on your partner’s computer with a few simple engagement rings pulled up—they’ll get the hint soon enough.)

According to New York City’s Catbird, a popular fine jewelry store in Brooklyn, “Your ring should fit your finger comfortably; snug enough so that it will not fall off, but loose enough to slide over your knuckle with some resistance.”

U.S. ring sizes follow a scale of numbers (and half numbers), typically from ring size 3 to 13.5 for adults. Women’s rings are commonly between sizes 3 and 9, while men’s rings are usually sized between 8 and 14. Those units match up to your finger’s width in millimeters: A ring size 3 fits a ring finger (or any finger) that is 14 millimeters across, and the sizes climb from there. The average ring size for women is between 5 and 7, but it’s always best to get an exact ring measurement before spending a lot of money—that average engagement ring cost isn’t cheap.

Before you sit down to measure your ring size, there are a few how-to pointers you should keep in mind:

• Consider your knuckle. If you know your knuckle is on the larger side, you should order half a size bigger than what your finger alone indicates, otherwise you won’t be able slide a ring into the right place.
• Ensure accuracy with multiple tries. Catbird’s site recommends measuring your finger three to four different times because the size actually fluctuates depending on temperature: It can be smaller the colder you are and more swollen if you’re overheated.

Below are three common and easy ways to measure your ring size at home—using string, a ring size chart, and a ring sizer—so you can get the right piece of jewelry, whether it’s a treat-yourself gift or a wedding ring.

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You can measure your ring size using either string or, perhaps a more common item in your home, floss. Take one of these measurement tools and wrap it around the base of your finger, marking where the string or floss first overlaps with a pen. Then, line that up with a ruler and take down its length in millimeters.

With standard ring sizes, every half-size matches up to a 0.4 millimeter increment, starting with size 3 equaling 14 mm, size 3.5 equal to 14.4 mm, size 4 equal to 14.8 mm, and so on. Common ring sizes for women are 6 (16.5 mm), 6.5 (16.9 mm), and 7 (17.3 mm). For men, the most common sizes are 10 (19.8 mm), 10.5 (20.2 mm), and 11 (20.6 mm).

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The ring size chart above should tell you how many millimeters the matching circle is as well as what ring size that measurement correlates to.

There is one caveat with this method: String and floss can stretch, so try not to force your measuring tool too taut. If you do, your measured ring finger size may be larger than your finger actually is, and any rings you purchase may be too big.

You can measure your ring size using a piece of jewelry that you already have and know fits you. Print out a true-to-size ring size chart—like this one from Catbird—and place your ring on the circles until you find the one that matches up with the inside circumference of your ring.

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If you’re worried about one of the above two strategies not guaranteeing accuracy, you can purchase your own ring-measurement tool. They don’t tend to be expensive, and there are many options online so, again, you don’t have to leave your house to get this step accomplished.

The best-reviewed ring-sizing tools fall into two categories: a thin measuring tape or a keyring lined with a gradient of ring sizes. Peacock Jewels has a top-rated measuring tape that works like a mini belt, with a sliding plastic arrow marker to measure your ring size ($3; amazon.com). It measures ring sizes 1 through 17 for women, men, and children. A top-rated ring of rings made by Mudder ($8; amazon.com) lets you try on sizes 1 through 13, including half sizes. It also works for women, men, and children.