How to measure finger sizes for a ring at home

How do you measure your ring size at home? The most accurate method is to use a ring that fits well and measure its inner diameter in millimeters. If you don’t have a ring that fits, you can measure the circumference of your finger with a strip of paper or a piece of string and divide the result by 3.14. It’s a good idea to repeat the measurement a few times, since finger size fluctuates throughout the day.

In short: how do you find your ring size?

At home, you can choose one of three methods:

1. Measure the inner diameter of a ring you already own that fits properly. This is the most reliable method to use at home.
2. Measure the circumference of your finger with a strip of paper or a piece of string. Divide the circumference in millimeters by 3.14.
3. Use a ring sizer. If you have one, measuring will be easier and more accurate than using a string.

If you get different results, don’t rush to choose a size based on just one measurement. Measure again at a different time of day.

How to Measure Your Ring Size at Home: 3 Methods

1. Measure the inner diameter of a ring that fits well

If you already have a ring that fits comfortably on the same finger, this is one of the easiest ways to determine your size. You’ll need a ruler with millimeter markings, or better yet, a caliper.

How to measure:

1. Place the ring on a flat surface.
2. Measure from one inner edge of the ring to the other.
3. Measure directly through the center of the ring.
4. Record the result in millimeters.
5. Repeat the measurement at least twice.

If the inner diameter is about 17 mm, this corresponds to approximately size 17 in the size system used. It is important to measure the inner diameter, not the outer diameter. The thickness of the ring’s sides is not included in the size measurement.

You can find more detailed size equivalents in the ring size chart.

2. Measure the circumference of your finger with a strip of paper

If you don’t have a ring that fits, you can measure your finger instead. A thin strip of paper is usually more convenient than elastic thread because it changes length less during measurement.

You will need:

• a narrow strip of paper;
• a pen;
• a ruler with millimeter markings.

Measuring instructions:

1. Wrap the strip around the part of your finger where you’ll wear the ring.
2. The strip should fit snugly but not cut into the skin.
3. Mark the point where the two ends of the strip meet.
4. Unfold the strip.
5. Measure its length in millimeters.
6. Repeat the measurement 2–3 times.

The resulting number is the approximate circumference of your finger.

3. How do you measure ring size with a piece of string?

The principle is the same as when using a paper strip: wrap the string around your finger, mark where the ends meet, and measure its length in millimeters. However, this method carries a higher risk of error.

It’s easy to:

• pull the thread too tight;
• press it against the skin;
• hold it too loosely;
• mark the spot inaccurately.

Therefore, if you get results of, say, 16.8, 17.1, and 17.4 mm when measuring with a string, you shouldn’t simply choose one of them. It’s better to repeat the measurement with a paper strip or try on a ring that fits.

Ring Size Calculator: How to Determine the Size from Circumference?

If you’ve measured your finger’s circumference, you can convert it to an approximate inner ring diameter. The formula is:

finger circumference in millimeters ÷ 3.14 = approximate inner ring diameter in millimeters

This can be used as a simple ring size calculator, but the result is still approximate. The tension in the paper or string can alter the result by as much as a few millimeters.

Ring sizes in cm: how to convert?

If you’re measuring your finger circumference in centimeters, first convert the result to millimeters.

For example:

5.34 cm = 53.4 mm

Then:

53.4 ÷ 3.14 ≈ 17 mm

So, according to this approximate calculation, a finger circumference of 5.34 cm would correspond to a ring with an inner diameter of approximately 17 mm. To compare more sizes, it’s better to use a separate ring size chart rather than listing all the equivalents in this article.

When is the best time to measure your finger size?

Finger circumference isn’t completely constant. It can be affected by hand temperature, physical activity, and the time of day. To ensure the most accurate measurement:

• measure when your hands are at normal temperature;
• do not measure immediately after coming in from extreme cold;
• do not measure immediately after intense exercise;
• avoid measuring when your fingers are visibly swollen;
• measure the same finger several times;
• if possible, repeat the measurement at a different time of day.

If several measurements differ, it’s best to focus not on a single random number, but on a consistent result.

Why should you measure the specific finger the ring is intended for?

Even on the same person, corresponding fingers on both hands are not necessarily the same size. Therefore, if you plan to wear the ring on the ring finger of your left hand, you should measure that specific finger.