A ring that fits well is one you forget you are wearing. Too tight and it pinches by the afternoon; too loose and it spins, slides over the knuckle, and one day goes down a drain. Getting the size right takes a few minutes and a little patience, and it matters most for the rings you plan to wear every day.
Here is how ring sizing works, the ways to measure, and the things that throw a measurement off.
How Ring Sizes Work
In the United States, ring sizes run on a number scale, usually from about 3 to 13, in half and quarter steps. Each whole size adds roughly 0.8 millimeters to the inside diameter of the ring, or about 2.5 millimeters to the inside circumference. That sounds tiny, but half a size is the difference between a ring that slides on comfortably and one that will not pass the knuckle.
Other countries use different systems. The United Kingdom and Australia use letters, and much of Europe uses the inside circumference in millimeters. If you are buying from overseas, check which system the size is written in.
Common women's sizes run from about 5 to 7, and common men's sizes from about 8 to 11, but plenty of people sit outside those ranges.
The Most Reliable Way: Ring Gauges
Jewelers size fingers with a set of metal sizing rings, one for every half or quarter size. You try them on until one slides over the knuckle with a little resistance and sits snugly without pinching. It is quick, and it is the most accurate method because it measures the way a real ring fits: as a rigid circle that has to pass the knuckle.
If the ring you have in mind has a wide band, ask to try a wide gauge as well. Wide bands fit tighter than narrow ones at the same size.
Measuring a Ring That Already Fits
The next best method is to measure a ring that already fits the right finger. Lay it on a ruler and measure the inside diameter, edge to edge on the inside, in millimeters. Then compare it with these approximate US sizes:
- 14.9 mm: size 4
- 15.7 mm: size 5
- 16.5 mm: size 6
- 17.3 mm: size 7
- 18.1 mm: size 8
- 19.0 mm: size 9
- 19.8 mm: size 10
- 20.6 mm: size 11
- 21.4 mm: size 12
Measure across the widest inside point, and use a ring with a band width similar to the one you want. A thin stacking ring and a wide band that both fit the same finger can measure differently.
The String or Paper Method, and Its Limits
Wrapping a strip of paper or a piece of string around the finger, marking where it meets, and measuring the length gives you the circumference. Divide by 3.14 for the diameter and use the chart above.
It is the least reliable method. String stretches and compresses, paper can be wrapped too tight or too loose, and neither tells you whether the ring will pass your knuckle. If you use it, use a non stretch strip, measure three times, and treat the result as a starting point rather than a final answer.
Printable ring sizers have the same weakness, plus one more: if the printer scales the page even slightly, every size on it is wrong. If you use one, check the printed ruler against a real ruler first.
What Changes Your Size
Fingers are not a fixed size. They change through the day and with the weather:
- Heat and humidity make fingers swell. Cold makes them shrink, which is why rings feel loose in winter or in heavy air conditioning.
- Time of day matters. Fingers can change size between morning and evening, so measure more than once, at different times.
- Exercise, salty food and flying can all cause temporary swelling.
- Your dominant hand is usually a little larger than the other, so the same finger on each hand can be different sizes.
The best time to measure is in the afternoon or evening, at a comfortable room temperature, on a normal day. In Hawaii, where it is warm most of the year, a ring sized here may feel a touch looser on a winter trip to the mainland. That is normal, and it is better than a ring that is tight every summer afternoon.
Knuckles and Wide Bands
A ring has to pass over the knuckle and still sit comfortably at the base of the finger. If your knuckles are noticeably larger than the base of your finger, size for the knuckle so the ring goes on and off without a struggle. A ring sized that way may turn a little at the base; a jeweler can add small sizing beads or bars inside the band to keep it upright.
Wide bands cover more of the finger, so they feel tighter. For a band wider than about 6 millimeters, many people need a quarter to a half size larger than they wear in a thin ring.
Sizing a Ring for a Surprise
Planning a proposal or a gift without giving it away takes some care:
- Borrow a ring they already wear on the same finger, measure it, and return it before it is missed. A ring from the other hand or another finger will not be the same size.
- If you cannot take it, press it into a bar of soap or trace the inside edge carefully on paper.
- Ask a close friend or family member, who may know the size or can find out.
- When in doubt, go slightly larger. Most rings are easier to make smaller than larger.
Rings That Are Hard to Resize
Most plain gold and silver bands can be resized up or down by a size or so. Some designs make it difficult or impossible, so it is worth getting the size right first time:
- Eternity bands, with stones set all the way around.
- Rings with a continuous pattern or engraving around the whole band, which a resize would interrupt.
- Tension settings, where the band itself holds the stone.
- Tungsten, titanium and similar metals, which generally cannot be resized at all.
If you are designing a ring from scratch, the size is part of the design, so settle it early. Our guide to custom engagement rings walks through the rest of the process, and you can get in touch to start talking about a custom piece.
