⚖️ Comparison · Updated for 2026
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.
Quick answer: UK uses letter sizes (A through Z+6). US uses number sizes (1 through 15+). UK J = US 4.75. UK L = US 6. UK N = US 6.75. UK P = US 7.75. UK R = US 8.75. Ring sizing varies by country, jeweller, and whether you're measuring inner diameter (mm) or circumference.
Decision guide — when to use which
Use UK ring sizes (letters) when…
UK and Ireland jewellers, British jewellery sizing.
Use US/Canada ring sizes (numbers) when…
US, Canada, most of the Americas.
📊 Side-by-side comparison
| 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 = 49.3 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.
Reviewed for 2026. All conversion factors and historical references verified against official sources (ISO standards, government weights & measures legislation, IEC technical specifications). Built by a UK-based qualified primary teacher and FA Level 2 coach as part of 247QuickTools' free utility-tools project. We don't sell SEO links or accept paid placements in this content.