We craft our rings using U.S. and Canada ring size standards, ensuring accurate fit and heirloom-level craftsmanship. For the most precise sizing, we recommend visiting a local jewelry store where your finger can be measured professionally using calibrated tools.
If you prefer to measure at home, we’ve included a safer method below - along with an International Ring Size Conversion Chart to help you find your size in different standards.
How to Measure Your Ring Size at Home
Wrap a thin strip of paper or soft string around the base of your finger.
Mark the point where the ends meet.
Flatten the strip and measure it in millimeters.
Use the chart below to match your measurement with the closest size.
International Ring Size Conversion Chart
RING SIZE CONVERSION CHART. US SIZES, CANADA SIZES, UK SIZES, INCHES, MM
Inside Diameter
Inside Circumference
Sizes
MM
Inches
MM
Inches
British & Australian
US & Canada
French & Russian
German
Japanese
Swiss
9.91
0.390
31.13
1.22
-
0000
-
-
-
-
10.72
0.442
33.68
1.39
-
00
-
-
-
-
11.53
0.454
36.22
1.43
-
0
-
-
-
-
11.95
0.474
37.54
1.49
A
1/2
-
-
-
-
12.18
0.482
38.26
1.51
A 1/2
3/4
-
-
-
-
12.37
0.487
38.86
1.53
B
1
-
-
1
-
12.60
0.496
39.58
1.56
B 1/2
1 1/4
-
-
-
-
12.78
0.503
40.15
1.58
C
1 1/2
-
-
-
-
13.00
0.512
40.84
1.61
C 1/2
1 3/4
-
-
-
-
13.21
0.520
41.50
1.63
D
2
41 1/2
13 1/2
2
1 1/2
13.41
0.528
42.13
1.66
D 1/2
2 1/4
-
-
-
-
13.61
0.536
42.76
1.68
E
2 1/2
42 3/4
13 3/4
3
2 3/4
13.83
0.544
43.45
1.71
E 1/2
2 3/4
-
-
-
-
14.05
0.553
44.14
1.74
F
3
44
14
4
4
14.15
0.557
44.45
1.75
F 1/2
3 1/8
-
-
-
-
14.25
0.561
44.77
1.76
F 3/4
3 1/4
-
-
-
-
14.36
0.565
45.11
1.77
G
3 3/8
45 1/4
-
5
5 1/4
14.45
0.569
45.40
1.79
G 1/4
3 1/2
-
14 1/2
-
-
14.56
0.573
45.74
1.80
G 1/2
3 5/8
-
-
6
-
14.65
0.577
46.02
1.81
H
3 3/4
46 1/2
-
-
6 1/2
14.86
0.585
46.68
1.84
H 1/2
4
-
15
7
-
15.04
0.592
47.25
1.86
I
4 1/4
47 3/4
-
-
7 3/4
15.27
0.601
47.97
1.89
I 1/2
4 1/2
-
15 1/4
8
-
15.40
0.606
48.38
1.90
J
4 5/8
49
15 1/2
-
9
15.53
0.611
48.79
1.92
J 1/4
4 3/4
-
-
-
-
15.70
0.618
49.32
1.94
J 1/2
5
-
15 3/4
9
-
15.80
0.622
49.64
1.95
K
5 1/8
50
-
-
10
15.90
0.626
49.95
1.97
K 1/4
5 1/4
-
-
-
-
16.00
0.630
50.27
1.98
K 1/2
5 3/8
-
-
10
-
16.10
0.634
50.58
1.99
L
5 1/2
51 3/4
16
-
11 3/4
16.30
0.642
51.21
2.02
L 1/4
5 3/4
-
-
-
-
16.41
0.646
51.55
2.03
L 1/2
5 7/8
-
-
-
-
16.51
0.650
51.87
2.04
M
6
52 3/4
16 1/2
12
12 3/4
16.71
0.658
52.50
2.07
M 1/2
6 1/4
-
-
-
-
16.92
0.666
53.16
2.09
N
6 1/2
54
17
13
14
17.13
0.674
53.82
2.12
N 1/2
6 3/4
-
-
-
-
17.35
0.683
54.51
2.15
O
7
55 1/4
17 1/4
14
15 1/4
17.45
0.687
54.82
2.16
O 1/2
7 1/4
-
-
-
-
17.75
0.699
55.76
2.20
P
7 1/2
56 1/2
17 3/4
15
16 1/2
17.97
0.707
56.45
2.22
P 1/2
7 3/4
-
-
-
-
18.19
0.716
57.15
2.25
Q
8
57 3/4
18
16
17 3/4
18.35
0.722
57.65
2.27
Q 1/2
8 1/4
-
-
-
-
18.53
0.729
58.21
2.29
Q 3/4
8 1/2
-
18 1/2
17
-
18.61
0.733
58.47
2.30
R
8 5/8
59
-
-
19
18.69
0.736
58.72
2.31
R 1/4
8 3/4
-
-
-
-
18.80
0.740
59.06
2.32
R 1/2
8 7/8
-
-
-
-
18.89
0.748
59.34
2.35
R 3/4
9
-
19
18
-
19.10
0.752
60.00
2.36
S
9 1/8
60 1/4
-
-
20 1/4
19.22
0.757
60.38
2.38
S 1/4
9 1/4
-
-
-
-
19.31
0.760
60.66
2.39
S 1/2
9 3/8
-
-
-
-
19.41
0.764
60.98
2.40
S 3/4
9 1/2
-
19 1/2
19
-
19.51
0.768
61.29
2.41
T
9 5/8
61 1/2
-
-
21 1/2
19.62
0.772
61.64
2.43
T 1/4
9 3/4
-
-
-
-
19.84
0.781
62.33
2.45
T 1/2
10
-
20
20
-
20.02
0.788
62.89
2.48
U
10 1/4
62 3/4
-
21
22 3/4
20.20
0.797
63.46
2.50
U 1/2
10 1/2
-
20 1/4
22
-
20.32
0.800
63.84
2.51
V
10 5/8
63
-
-
23 3/4
20.44
0.805
64.21
2.53
V 1/4
10 3/4
-
-
-
-
20.68
0.814
64.97
2.56
V 1/2
11
-
20 3/4
23
-
20.76
0.817
65.22
2.57
W
11 1/8
65
-
-
25
20.85
0.821
65.50
2.58
W 1/4
11 1/4
-
-
-
-
20.94
0.824
65.78
2.59
W 1/2
11 3/8
-
-
-
-
21.08
0.830
66.22
2.61
W 3/4
11 1/2
-
21
24
-
21.18
0.834
66.54
2.62
X
11 5/8
66 1/4
-
-
26 1/4
21.24
0.836
66.73
2.63
X 1/4
11 3/4
-
-
-
-
21.30
0.839
66.92
2.64
X 1/2
11 7/8
-
-
-
-
21.49
0.846
67.51
2.66
Y
12
67 1/2
21 1/4
25
27 1/2
21.69
0.854
68.14
2.68
Y 1/2
12 1/4
-
-
-
-
21.89
0.862
68.77
2.71
Z
12 1/2
68 3/4
21 3/4
26
28 3/4
22.10
0.870
69.43
2.73
Z +1/2
12 3/4
-
-
-
-
22.33
0.879
70.15
2.76
Z+1
13
-
22
27
-
22.60
0.890
71.00
2.80
Z+1.5
13.5
-
-
-
-
22.69
0.893
71.28
2.81
Z+2
-
-
-
-
-
22.92
0.902
72.00
2.83
Z+2.5
-
-
-
-
-
23.06
0.908
72.45
2.85
Z+3
-
-
-
-
-
23.24
0.915
73.01
2.87
Z+3.5
-
-
-
-
-
23.47
0.924
73.73
2.90
Z+4
-
-
-
-
-
23.55
0.927
73.98
2.91
Z+4.5
-
-
-
-
-
23.87
0.940
74.99
2.95
Z+5
-
-
-
-
-
24.27
0.956
76.25
3.00
Z+6
-
-
-
-
-
Additional Tips for the Best Fit
Allow adequate area for your knuckle to fit.
Keep in mind that various fingers on the same and opposite hands may have different sizes.
Take a measurement of the finger where the ring will be worn.
Take your finger measurement at the end of the day, when it is most likely to be the longest.
Order a size up (larger) if you are in-between sizes.
If your finger is cold or hot, make sure it is at room temperature.
Take two different measurements and choose a size in the middle of your knuckle that is substantially larger than your finger's base. A ring should fit perfectly over your knuckle but must not be too loose; otherwise, it will keep moving around your finger.
Need More Guidance?
You can always reach out to us for help or refer to our full ring sizing article for deeper insights into selecting your perfect fit. We’re here to make sure your BlackTreeLab piece becomes a lifelong companion - crafted to fit you perfectly from the very first wear.
