How to Measure Your Ring Size (with Ring Size Chart)

There are three practical ways to measure ring size at home, and they are not equally reliable. The order below is from most to least dependable.

1. Trace a ring that already fits. This is the method the GIA recommends. Take a ring the wearer already wears comfortably on the correct finger, set it on paper, and trace the inside edge of the band. Measure the diameter of that circle in millimeters and read it against the chart above. Because it uses an existing, correctly sized ring, it sidesteps the guesswork of measuring a finger directly.
2. Take a soap or wax impression. GIA also suggests pressing a ring firmly into a bar of soap to leave a clean impression, then bringing that to a jeweler to measure. It is a good way to capture a borrowed ring without keeping it.
3. Measure the finger with a strip — carefully. Wrap a thin strip of paper or a flexible tape snugly around the base of the finger, mark where it meets, and measure that length as the circumference. This is the familiar method, but it is the least accurate: GIA warns that “string can stretch and paper can be easily damaged,” and that humidity can make paper “shrink and curl.” If you use it, use paper rather than string, keep it snug but not tight, and repeat it several times.

Whichever method you use, remember what you are measuring: the ring must slide over the knuckle, so if the knuckle is much larger than the base of the finger, size to pass the knuckle and consider a ring guard to stop it spinning.

Related: Lilly M. Size Guide

A ring sizer is a small tool that turns measuring into reading off a number, and there are three kinds, again in order of reliability.

• A reusable plastic ring sizer. This belt-style loop, marked with sizes, tightens around the finger and reads the size directly. It costs very little, is more dependable than paper, and is the easiest way to find your ring size at home more than once.
• A printable paper ring sizer. Many jewelers offer one to download. The catch is printer scaling: print at 100% with no “fit to page,” and before cutting, check the ruler or scale bar on the sheet against a real ruler — even a few percent of scaling error throws the size off. Once verified, cut the strip, thread it through its own slot, and snug it around the finger.
• A set of sample sizing rings. The most accurate at-home option is to order a ring sizer set — a band of graduated sizing rings you try on directly, exactly as you would in a shop.

Any of these is a better way to measure ring size than a length of string, because each is built to the size standard rather than approximating it. Whichever you use, apply the same timing rules below.

Reading the chart is the last step in how to measure ring size: it converts a physical measurement into a size, and the two measurements it lists are simply two ways of describing the same circle.

• Inside diameter is the straight-line distance across the inside of the band. Use this figure when you have traced an existing ring and measured across the circle you drew.
• Inside circumference is the distance around the inside of the band. Use this figure when you have measured around the finger itself with a strip.

Find your measurement in the relevant column and read across to the US size. If your number falls between two rows, take the larger size — it is easier to make a ring smaller than larger, a point we return to below. The international equivalents beneath the chart are approximate; UK sizes use letters and European sizes track the circumference in millimeters, but the conversions vary slightly between systems, so confirm the exact size with your jeweler before a ring is made.

One quiet source of error is worth naming: measure the correct finger and the correct hand. The left and right ring fingers are often a half-size apart, and the dominant hand tends to be slightly larger.

Timing matters more than most people expect, because a finger is not a fixed size. The GIA puts it plainly: “Fingers shrink in the cold and swell in the heat,” so “a measurement taken on a cool morning can also differ from one taken in the afternoon.”

The practical rules that follow are simple:

• Measure at the end of the day, when the finger is at its largest, so the ring is not too tight in the evening or after activity.
• Measure when your hands are warm, not straight after coming in from the cold or holding a cold drink.
• Avoid measuring when the body is retaining water — after intense exercise, a salty meal, or for some people at particular times — which can add most of a size.
• Take the reading two or three times on different days and average it, rather than trusting a single measurement.

The proposal problem — needing a size without asking — has a few honest solutions, in rough order of reliability.

• Borrow a ring she already wears on the correct finger and trace or take a soap impression of it, then return it before it is missed. This is by far the most accurate route.
• Ask someone who would know — a close friend or family member — to help, or to try on rings with her under another pretext.
• Compare against your own finger. Slide her ring onto your own finger and mark how far it goes; a jeweler can estimate from that.
• Choose a size you can adjust. When all else fails, order a common average — around a US 6 to 6.5 for many women — and plan on a resizing afterward, which is often the most romantic-practical compromise.

If a resize will likely be needed, it is worth choosing a design and metal that resize easily, and buying from a maker who offers resizing — a point that turns a guess into a non-problem.

Related: Bespoke & Personalization

Two common situations call for a deliberate choice rather than a straight reading of the chart.

Between two sizes. Round up to the larger size. A slightly loose ring can be made smaller easily and can be held in place temporarily with a ring guard or sizing beads; a ring that is genuinely too small is harder to enlarge and uncomfortable in the meantime.

A wide band. A wide shank sits against more of the finger and therefore fits more snugly than a thin one at the same nominal size. As GIA notes, “rings with wide shanks usually need to be a bit larger.” A good rule is to add roughly a quarter to a half size for a broad band, and to try a wide sizer if you can rather than trusting a measurement taken with a thin one.

Comfort-fit bands, which are domed on the inside, also tend to slip on more easily and can be taken a touch smaller than a flat-profile band. When a ring is being made to order, these are exactly the details worth settling in advance.

Usually, yes — and knowing the limits in advance takes the pressure off getting the size perfect on the first try. Most plain and lightly set rings in gold or platinum can be sized up or down by a size or two without trouble, and GIA notes the general rule that metal is easier to remove from a ring that is too big than to add to one that is too small.

Some designs resist resizing, and it is better to know which before buying:

• Full eternity bands set with stones all the way around cannot usually be sized, because there is no plain metal to cut and rejoin; they are made to a fixed size or remade.
• Channel-set and heavily pavé shanks can be sized only within narrow limits before the stones are disturbed.
• Tension settings rely on precise spring pressure and generally cannot be resized.

Our own pieces are made to order, so the size is built in from the start, and because we make them we also resize and repair them — in gold from 9 to 18 karat and in platinum. If a ring is a gift and the size is a guess, that is the safety net: the piece can be brought back and fitted properly.

Related: Support & FAQ

Knowing how to measure ring size comes down to measuring the right thing at the right time and reading it against a reliable chart. The most accurate home method is to trace a ring that already fits and match its inside diameter to a US size; the familiar string-around-the-finger method is the least accurate, and the GIA cautions against relying on it.

Whatever method you use, measure when your hands are warm and at the end of the day, take the reading more than once, size for the knuckle, and allow a little extra for a wide band. Where a measurement lands between two sizes, round up — a ring is more easily made smaller than larger.

And treat the first size as a good estimate rather than a final verdict. Nearly every ring except a full eternity band or a tension setting can be adjusted, and for a made-to-order piece the size is built in and can be fitted later if a gift misses by a little. Measured carefully and, for anything valuable, confirmed by a jeweler, your ring size is one detail you only need to get right once.