|
Inside
|
Inside
|
Inside
|
Inside
|
Number Sizes
|
Approx.
|
Approx.
|
Approx.
|
|
Diameter
|
Diameter
|
Circumference
|
Circumference
|
US/Canada
|
British/
|
Japanese
|
Swiss
|
|
(inches)
|
(mm)
|
(inches)
|
(mm)
|
Standard
|
Australian
|
Equivalent
|
Equivalent
|
|
|
|
|
|
|
Equivalent
|
|
|
|
0.618
|
15.7
|
1.941
|
49.3
|
5
|
J 1/2
|
9
|
|
|
0.626
|
15.9
|
1.966
|
49.9
|
5 1/4
|
K
|
|
10.00
|
|
0.634
|
16.1
|
1.991
|
50.6
|
5 1/2
|
K 1/2
|
10
|
|
|
0.642
|
16.3
|
2.016
|
51.2
|
5 3/4
|
L
|
|
11.75
|
|
0.650
|
16.5
|
2.041
|
51.8
|
6
|
L 1/2
|
11
|
12.75
|
|
0.658
|
16.7
|
2.066
|
52.5
|
6 1/4
|
M
|
12
|
|
|
0.666
|
16.9
|
2.091
|
53.1
|
6 1/2
|
M 1/2
|
13
|
14.00
|
|
0.674
|
17.1
|
2.116
|
53.8
|
6 3/4
|
N
|
|
|
|
0.682
|
17.3
|
2.141
|
54.4
|
7
|
N 1/2
|
14
|
15.25
|
|
0.690
|
17.5
|
2.167
|
55.0
|
7 1/4
|
O
|
|
|
|
0.698
|
17.7
|
2.192
|
55.7
|
7 1/2
|
O 1/2
|
15
|
16.50
|
|
0.706
|
17.9
|
2.217
|
56.3
|
7 3/4
|
P
|
|
|
|
0.714
|
18.1
|
2.242
|
56.9
|
8
|
P 1/2
|
16
|
17.75
|
|
0.722
|
18.3
|
2.267
|
57.6
|
8 1/4
|
Q
|
|
|
|
0.730
|
18.5
|
2.292
|
58.2
|
8 1/2
|
Q 1/2
|
17
|
|
|
0.738
|
18.7
|
2.317
|
58.9
|
8 3/4
|
R
|
|
19
|
|
0.746
|
18.9
|
2.342
|
59.5
|
9
|
R 1/2
|
18
|
|
|
0.754
|
19.2
|
2.368
|
60.1
|
9 1/4
|
S
|
|
20.25
|
|
0.762
|
19.4
|
2.393
|
60.8
|
9 1/2
|
S 1/2
|
19
|
|
|
0.770
|
19.6
|
2.418
|
61.4
|
9 3/4
|
T
|
|
21.5
|
|
0.778
|
19.8
|
2.443
|
62.1
|
10
|
T 1/2
|
20
|
|
|
0.786
|
20.0
|
2.468
|
62.7
|
10 1/4
|
U
|
21
|
|
|
0.794
|
20.2
|
2.493
|
63.3
|
10 1/2
|
U 1/2
|
22
|
22.75
|
|
0.802
|
20.4
|
2.518
|
64.0
|
10 3/4
|
V
|
|
|
|
0.810
|
20.6
|
2.543
|
64.6
|
11
|
V 1/2
|
23
|
|
Ring sizing is difficult to guess, even in person, without being measured using a ring gauge sizer. Keep in mind that finger size is prone to change with temperature, humidity, exercise, what you have been eating, time of day, time of the month, pregnancy and other factors. Your dominant hand is usually 1/2 size larger. Take the knuckle into consideration when sizing – the base of your finger may be smaller than your knuckle, yet it needs to get over the knuckle to slip on.
The best size is the ring that fits snugly and gives a little resistance when you take it off. Rings with wide bands should be a little looser than narrow rings.
As a guide, the average ring finger sizes for women are a size 6 to 8 (US equivalent) / L to Q (British equivalent).
Note: I tend to use the US equivalent for sizing the rings you see on this site.