If you’ve ever ordered a ring online (or tried to figure out your ring size so you could tell someone who wanted to surprise you with a gift!), you may have found yourself stumped with how to measure your finger at home. There are a few simple things to remember, and lots of ways to figure out the right size without leaving your house.

Getting started

The basic objective for determining your ring size is to measure your finger’s width in millimeters and match it up to a guide. (As a general rule of thumb, women’s rings tend to fall somewhere between a size 3 and a 9 in the U.S.) Before you take your measurement:

1. Choose the finger you’re going to match the ring to.
2. Keep in mind that the fingers on your dominant hand tend to be larger than your other hand.
3. Don’t forget to size up slightly to accommodate your knuckle.
4. Measure more than once — and at different times throughout the day. Cold weather can shrink your fingers, while heat, exercise, water retention or even illness can cause your finger to swell.

Let’s get measuring

While having your finger professionally measured in a jewelry store is ideal for accuracy (and we’re happy to help you anytime here at Swierenga’s), here are a few things to help you do it at home:

1. Use a small piece of string or dental floss. Cut a couple inches of thread or floss and wrap it around the base of your finger. If you’re using dental floss, make sure you don’t pull it too tightly. In order to get an accurate read, the floss should slip off your finger relatively easily. Mark where the string or floss overlaps with a pen or marker. Then line that segment up with a ruler and write down the length in millimeters. (If your size seems to fall between two numbers — it’s always best to size up. Keep in mind that different ring thicknesses will fit tighter of looser than the floss will. And don’t forget to accommodate for the knuckle!)
2. Place a ring you already have on a sizing chart. The internet is loaded with printable charts you can use to compare a ring you already have. These charts typically print true-to-size, and you simply have to compare your ring to the measurements or circles provided until you find the one that matches your ring’s circumference. All circles are listed in millimeters and their corresponding ring size.
3. Buy a ring sizer. If you’re worried about the accuracy of the ideas listed above, you can always purchase an official ring-measurement tool — a thin measuring tape of a keyring lined with a series of brass circles to try.