Are US and UK ring sizes the same?

No. US sizes use numbers (e.g., 7), while UK sizes use letters (e.g., N). A US 7 is approximately UK N½. Always confirm with a jeweler before ordering.

How do I measure my ring size at home?

Wrap a thin strip of paper around your finger, mark where it overlaps, and measure the length in mm — that is your inner circumference. Enter it into the chart to find your size.

What is the most common US ring size for women?

US sizes 5–7 (UK J½–N½) are most common for women. US 9–11 (UK R½–V½) are typical for men.

Does the converter handle half sizes?

Yes. All standard US half sizes (e.g., 5.5, 7.5) are supported and map to the correct UK letter with the exact mm measurements.

US Ring Size to UK Ring Size Converter

Convert US ring sizes to UK letter sizes with inner circumference and diameter in millimeters.

Enter US Ring Size

US Size

Range: 0 – 16 (half sizes supported)

Or enter inner circumference

Full Size Chart

Highlighted row = your size

US	UK	Circ (mm)	Diam (mm)

Summary

Convert US ring sizes to UK letter sizes with inner circumference and diameter in millimeters.

How it works

US ring sizes use a numeric scale (0–16, with half sizes).
UK ring sizes use a letter scale (A–Z+6), where each letter step is roughly 1.25 mm in circumference.
Inner circumference (mm) = (US size × 2.5553) + 36.5. Diameter = circumference / π.
The converter maps US size to the nearest UK letter and shows exact mm measurements.

Use cases

Order a ring from a UK jeweler when you only know your US size.
Verify a ring size before resizing.
Compare ring dimensions when shopping across US and UK stores.
Find the inner diameter to check if a ring will fit a specific finger measurement.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu