Quick Converter

Slide to your **inside diameter (mm)** or type it — we’ll suggest the nearest UK & US size.

Diameter: 17.30 mm · UK: O US: 7¼ Inner circumference: 54.3 mm

Tip: measure an existing ring’s **inside diameter** with a ruler/caliper to the nearest 0.1 mm.

Method A — Measure an existing ring

  1. Place a ring that fits the intended finger on a ruler.
  2. Measure the **inside diameter** edge-to-edge (mm).
  3. Use the converter above to find the nearest UK size.

For accuracy, measure to 0.1 mm (digital calipers are best).

Method B — Paper/cord wrap

  1. Wrap a thin strip of paper around the base of the finger (snug but not tight).
  2. Mark the overlap, lay flat, measure the **length** in mm = inner **circumference**.
  3. Divide by π (3.1416) to get **diameter** — or compare circumference to the table.

Measure at the end of the day when fingers are warm. Avoid after exercise/cold.

UK ⇄ US Conversion (Approx.)

Use as a guide — styles with wide bands may feel tighter. If between sizes, consider a half size larger.

UK
US
Inner Ø (mm)
Inner Circ. (mm)
F
3
14.07
44.2
G
3½
14.48
45.5
H
4
14.88
46.7
I
4½
15.29
48.0
J
4¾
15.49
48.7
K
5¼
15.90
49.9
L
5¾
16.31
51.2
M
6¼
16.71
52.5
N
6¾
17.12
53.8
O
7¼
17.53
55.1
P
7¾
17.93
56.3
Q
8¼
18.34
57.6
R
8¾
18.75
58.9
S
9¼
19.15
60.1
T
9¾
19.56
61.4
U
10¼
19.96
62.7
V
10¾
20.37
64.0
W
11¼
20.78
65.3
X
11¾
21.18
66.5
Y
12¼
21.59
67.8
Z
12¾
21.99
69.1

Need sizes below F or above Z (e.g., Z+)? Contact us — we can advise on special orders.

Fit Tips

  • Fingers change size through the day and with temperature. Measure a few times for the best average.
  • Wider bands fit tighter — consider going up half a size for bands ≥ 5–6 mm.
  • Stacking? Measure with all bands together.
  • If choosing a surprise gift, peek at a ring worn on the same finger/hand and measure its diameter.

Still unsure? We’re happy to help by chat or email.

Questions about sizing? support@rafyq.com · +44 7455 642908