UK ring sizes (letters) vs US/Canada ring sizes (numbers)
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
UK and Ireland jewellers, British jewellery sizing.
US, Canada, most of the Americas.
| Aspect | UK ring sizes (letters) | US/Canada ring sizes (numbers) |
|---|---|---|
| UK H | H | 4 |
| UK J | J | 4.75 |
| UK L | L | 5.75 |
| UK N | N | 6.75 |
| UK P | P | 7.75 |
| UK R | R | 8.75 |
| UK T | T | 9.75 |
| Measurement basis | Circumference in mm | Diameter in mm × π, scaled |
Frequently asked
How do I measure my ring size at home?
Wrap a narrow strip of paper around your finger, mark where it overlaps, and measure the length in mm — that's your circumference. UK size K is roughly 50-51 mm circumference. Online ring-size charts convert circumference to UK letters or US numbers.
Does ring size vary with temperature?
Yes. Fingers are typically 0.5-1 size larger in warm weather. Get sized in the afternoon (fingers are larger then) if you want a comfortable all-day fit.
Frequently asked questions
How do I measure my ring size at home?
Wrap a narrow strip of paper around your finger, mark where it overlaps, and measure the length in mm — that's your circumference. UK size K is roughly 50-51 mm circumference. Online ring-size charts convert circumference to UK letters or US numbers.
Does ring size vary with temperature?
Yes. Fingers are typically 0.5-1 size larger in warm weather. Get sized in the afternoon (fingers are larger then) if you want a comfortable all-day fit.