How to measure

How to measure a ring

Every point, drawn on the garment so there is no guessing where the tape goes.

Quick answer

A ring has two numbers: circumference, around the inside of the band, and diameter, straight across that opening. Circumference is the sizing number, and unlike a flat garment you take it around the band, not across a layer. Hover or tap each step on the diagram to see where the tool sits. Sizely keeps both on one chart.

A buyer matching your ring to one that already fits checks the inside circumference first, since that single number maps straight to a US, UK or EU size. Generic listings give one vague "size 7" and stop. This page shows both points on the band so the buyer can confirm the fit against a ring they own before they commit.

Create your free size chart

A
Circumference
The distance all the way around the inside of the band, taken with a flexible tape or a strip of paper wrapped inside the ring. This is the sizing number that converts to a US, UK or EU ring size, so it leads. Hover or tap this step to see where the line wraps.Recorded as-is, measured around the inside. Do not double.
B
Diameter
The straight line across the inside of the band, from one inner edge to the opposite inner edge. Lay the ring on a ruler or use a caliper and read the widest inner gap. It is the quickest check against a ring the buyer already owns.Recorded as-is, measured across the opening. Do not double.

Measure the inside of the band, never a stretched or worn one, and take it cold and flat on a table. A ring is small-scale, so work in millimeters for accuracy and convert after. Here the two numbers behave differently: circumference is read around the inner band, diameter is the straight line across the same opening. Neither one doubles, because you are already measuring the full inside of the ring, not a folded garment edge.

Ring size reference

Representative inside measurements in inches, ordered by fit-impact. Your real numbers go on your own chart.
Size	Circumference	Diameter
5	1.94	0.62
6	2.04	0.65
7	2.15	0.68
8	2.26	0.72
9	2.36	0.75

Frequently asked

What ring size am I?

Measure the inside circumference of a ring that already fits the right finger, then match it to a sizing scale. About 51.9 mm inside circumference is a US 6, 54.4 mm is a US 7, and roughly 2.5 mm separates each whole size. Fingers swell in heat and shrink in cold, so measure at room temperature. For the full US, UK and EU conversion, see our ring size conversion chart.

Do I measure ring circumference or diameter for sizing?

Circumference, the distance around the inside of the band, is the number that maps to a size. Diameter, the straight line across the inside, is easier to take with a ruler but you convert it to a size by multiplying by pi (about 3.14). Listing both lets a buyer use whichever tool they have at home.

Should I measure a ring in millimeters or inches?

Millimeters give cleaner numbers for jewelry because each whole ring size is only about a tenth of an inch apart, which is easy to misread on an inch ruler. Measure in millimeters, then show inches too if your buyers think that way. Stay consistent and label the unit on every listing.

Do men's and women's ring sizes use the same measurement?

The measurement method is identical, inside circumference and diameter, but men's rings simply run larger on average, often US 8 to 12 against a women's US 5 to 9. The same scale covers both, so one inside circumference always equals one size. Men can check our men's ring size chart for the typical range.

Why does my ring size feel different on a wide band?

A wide or thick band sits tighter because it covers more of the finger and traps less give, so the same inside circumference feels snugger than a thin band. Resellers often note that buyers size up a quarter to a half size for bands wider than about 6 mm. State the band width in your listing so buyers can adjust.