ring size & gold purity guide: quick reference chart

Ring size and gold purity are the two things buyers get stuck on most before ordering jewelry online — this page covers both in one place: a full US ring size chart with millimeter measurements, and a clear breakdown of what karat and gold-type terms actually mean.

Ring size chart (US sizes, with diameter)

To use this chart, measure the inside diameter of a ring that already fits (in millimeters), then find the closest match below.

| US Size | Diameter (mm) | US Size | Diameter (mm) | |---|---|---|---| | 3 | 14.1 | 8.5 | 18.5 | | 3.5 | 14.5 | 9 | 19.0 | | 4 | 14.9 | 9.5 | 19.4 | | 4.5 | 15.3 | 10 | 19.8 | | 5 | 15.7 | 10.5 | 20.2 | | 5.5 | 16.1 | 11 | 20.6 | | 6 | 16.5 | 11.5 | 21.0 | | 6.5 | 16.9 | 12 | 21.4 | | 7 | 17.3 | 12.5 | 21.8 | | 7.5 | 17.7 | 13 | 22.2 | | 8 | 18.1 | | |

US sizes run roughly 3 to 13 for adult rings, with each half-size adding about 0.4mm to the inside diameter. If you're between two sizes, sizing up is usually the safer call for comfort — a ring that's slightly loose is a quick fix, one that's too tight isn't wearable at all.

How to measure your own ring size at home

Wrap a strip of paper or string around the base of the finger, mark where it overlaps, then measure that length in millimeters — that's the circumference, not the diameter, so divide by roughly 3.14 (pi) to get the diameter to match against the chart above. Measure at the end of the day when fingers are at their largest, and avoid measuring right after exercise or in cold weather, both of which temporarily shrink finger size.

Gold purity chart (karat to percentage)

Karat measures how many parts out of 24 are pure gold — the rest is alloy metal, which affects both color and durability.

| Karat | % Pure Gold | Notes | |---|---|---| | 24k | 99.9% | Softest, most prone to scratching and bending | | 22k | 91.7% | Rarely used in everyday jewelry | | 18k | 75% | Strong balance of purity and durability | | 14k | 58.3% | Most common for everyday-wear jewelry | | 10k | 41.7% | Most durable, least pure |

Higher karat means more pure gold and a richer color, but also a softer metal — 14k is the most common choice for daily-wear pieces specifically because it holds up to regular wear better than 18k or 24k while still reading as real gold, not just gold-toned.

Gold-filled vs. gold-plated vs. vermeil — what's the actual difference

These terms get used almost interchangeably, but they describe meaningfully different things. Gold-plated jewelry uses a thin layer of gold (often well under a micron) electroplated over a base metal like brass — the least durable and least expensive option, and the plating can wear through with regular contact. Gold vermeil is sterling silver base plated with a thicker layer of gold — U.S. industry guidelines require at least 10k gold and a minimum 2.5-micron thickness, roughly five times thicker than standard plating, which is why vermeil holds up noticeably longer. Gold-filled jewelry mechanically bonds a much thicker layer of karat gold to a base metal, without electroplating — the most durable of the three non-solid options, though still not solid gold all the way through.

Find your size and finish

Once you know your size and what a gold-type label actually means, our jewelry collection shows what's currently available at each — check the listed material and size range on any product page against the charts above before ordering.