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Size converter Conversion chart How to measure Wide rings Sizing FAQ
A clearer way to choose
Ring size converter
Choose the size system or measurement you have. See the nearest US reference size and compare its measurements before selecting a product option.
Use the conversion table below if the interactive tool does not load. The full guide works without JavaScript.
Choose a size or enter a measurement to see your result.
Approximate US equivalent
US
Inside diameter
Inside circumference
EU / metric, approx.
UK / Australia, approx.
Japan, approx.
Find this row in the chart
A conversion is a reference, not a fit guarantee. Measurements match the nearest quarter-size row; an exact midpoint rounds up. Band width, shape and the fit over your knuckle still need checking. This tool does not add a wide-band allowance or check stock.
Ring size conversion chart
Read across from your US size to compare the inside diameter and inside circumference in millimetres. EU values below mean the metric circumference system, rounded to a whole millimetre. UK and Japanese labels are approximate cross-references, not identical manufacturing specifications.
Swipe across for international sizes. Scroll within the table for more rows. A dash means no equivalent is supplied in this guide.
US sizes 0–16 with inside measurements and approximate international equivalents
US / Canada
Diameter
Circumference
EU
UK / Australia
Japan
0
11.63
36.5
37
—
—
0.25
11.84
37.2
37
—
—
0.5
12.04
37.8
38
—
—
0.75
12.24
38.5
39
—
—
1
12.45
39.1
39
—
—
1.25
12.65
39.7
40
—
—
1.5
12.85
40.4
40
—
—
1.75
13.06
41.0
41
—
—
2
13.26
41.7
42
—
—
2.25
13.46
42.3
42
—
—
2.5
13.67
42.9
43
—
—
2.75
13.87
43.6
44
—
—
3
14.07
44.2
44
F 1/2
4
3.25
14.27
44.8
45
G
5
3.5
14.48
45.5
46
G 1/2
—
3.75
14.68
46.1
46
H
6
4
14.88
46.8
47
H 1/2
7
4.25
15.09
47.4
47
I
—
4.5
15.29
48.0
48
I 1/2
8
4.75
15.49
48.7
49
J
—
5
15.70
49.3
49
J 1/2
9
5.25
15.90
50.0
50
K
—
5.5
16.10
50.6
51
K 1/2
10
5.75
16.31
51.2
51
L
—
6
16.51
51.9
52
L 1/2
11
6.25
16.71
52.5
53
M
12
6.5
16.92
53.1
53
M 1/2
13
6.75
17.12
53.8
54
N
—
7
17.32
54.4
54
N 1/2
14
7.25
17.53
55.1
55
O
—
7.5
17.73
55.7
56
O 1/2
15
7.75
17.93
56.3
56
P
—
8
18.14
57.0
57
P 1/2
16
8.25
18.34
57.6
58
Q
—
8.5
18.54
58.3
58
Q 1/2
17
8.75
18.75
58.9
59
R
—
9
18.95
59.5
60
R 1/2
18
9.25
19.15
60.2
60
S
—
9.5
19.35
60.8
61
S 1/2
19
9.75
19.56
61.4
61
T
—
10
19.76
62.1
62
T 1/2
20
10.25
19.96
62.7
63
U
21
10.5
20.17
63.4
63
U 1/2
22
10.75
20.37
64.0
64
V
—
11
20.57
64.6
65
V 1/2
23
11.25
20.78
65.3
65
W
—
11.5
20.98
65.9
66
W 1/2
24
11.75
21.18
66.6
67
X
—
12
21.39
67.2
67
X 1/2
25
12.25
21.59
67.8
68
Y
—
12.5
21.79
68.5
69
Z
26
12.75
22.00
69.1
69
Z 1/2
—
13
22.20
69.7
70
—
27
13.25
22.40
70.4
70
Z+1
—
13.5
22.61
71.0
71
Z+2
—
13.75
22.81
71.7
72
—
—
14
23.01
72.3
72
—
—
14.25
23.22
72.9
73
—
—
14.5
23.42
73.6
74
—
—
14.75
23.62
74.2
74
—
—
15
23.83
74.8
75
—
—
15.25
24.03
75.5
76
—
—
15.5
24.23
76.1
76
—
—
15.75
24.43
76.8
77
—
—
16
24.64
77.4
77
—
—
This chart is a reference, not a list of sizes in stock. Millimetre measurements are rounded, and sizing charts can differ slightly between brands. Confirm the US option on the product page before ordering.
How to measure your ring size
01 / MOST RELIABLE Use a proper ring sizer
Have a jeweller measure the exact finger you will wear the ring on. Ask for a US size and try a gauge close to the width of your chosen band. It should pass over your knuckle with gentle resistance and sit comfortably at the base.
Measure when your hands are at a normal temperature. Repeat the check at different times, including later in the day. Do not assume matching fingers on opposite hands have the same size.
02 / AT-HOME ESTIMATE Measure a ring that fits
Inside edge ↔ inside edge
Choose a round ring that fits the intended finger and has a similar band width.
Use a millimetre ruler or calliper to measure straight across the centre of the opening.
Measure the inside , excluding the metal on both sides.
Select “Inside diameter” in the converter and enter the measurement.
A bent, oval or open adjustable ring cannot provide a dependable round-ring diameter.
Avoid string as your final sizing method. It can stretch, and a strip wrapped around the finger does not reproduce how a rigid ring passes over the knuckle. Treat a circumference taken this way as an estimate and check it with a proper sizer before ordering.
Sizing wide gothic and biker rings
A chunky skull face or broad gothic band makes a strong statement, but fit depends on the part that surrounds your finger. The width of the decorative face is not the same as the width of the band underneath.
A wide band can feel tighter than a slim ring in the same US size. Try a comparable wide sizer rather than automatically adding a full size. The converter does not apply a blanket size increase.
Check the product's measurements and size options. If the shape, taper or inner profile makes you unsure, send us the product link together with your measured US size and the width of the ring or sizer used.
Ask about my fit
Before you choose a size
Between two readings? Re-measure and compare both neighbouring sizes with a sizer. A larger label is not automatically a better fit.
Buying a gift? Measure a ring worn on the same finger, or ask for the person's size. Height, clothing size and average men's or women's sizes cannot identify their fit.
Adjustable design? Follow the range and adjustment instructions on that product. “Adjustable” does not mean every finger size will fit.
Thinking about resizing later? Check first. Stones, engraving, plating and detailed bands can limit what a jeweller can alter.
Wrong fit after delivery? Contact us before changing or wearing the item. Our 45-day return policy explains eligibility and how to start a return.
Ring sizing FAQ
What size system does Gothicrock use? Fixed-size ring options use US sizes, including half or quarter sizes where offered. Choose from the actual options on the product page. A size shown in this guide is not a promise that every design is made in that size.
Is diameter the same as circumference? No. Diameter is the straight line across the inside of a round ring. Circumference is the distance around that opening. For a circle, circumference equals diameter multiplied by pi (approximately 3.1416). Do not enter a circumference into the diameter field.
What is US ring size 8 in millimetres? In this guide, US 8 is approximately 18.14 mm inside diameter and 57.0 mm inside circumference. Use those figures as a reference and check the actual fit with a sizer of similar width.
Can I convert centimetres or inches? Yes. Choose inside diameter or circumference, then select mm, cm or inches. For example, 1.814 cm inside diameter equals 18.14 mm and is close to US 8 in this chart.
Are men's and women's ring sizes different? The US size scale is the same. A US 8 describes the same nominal size regardless of who wears it. Finger shape, band width and the ring's inner profile affect the fit.
Can I place my ring on the screen to measure it? No. The illustration on this page is not a calibrated sizer. Screen size and zoom change its displayed scale. Measure with a physical ruler, calliper or proper ring sizer.
Why does another international chart give a different answer? Regional labels, rounding and measuring practices can vary. Compare the inside measurement in millimetres and ask a jeweller to confirm your US size. The converter gives the nearest reference row; it does not guarantee the fit of a specific ring.
Payment methods Available options are shown at checkout.
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About this guide and its references Updated 11 September 2026. The converter and table use the same reference rows. US and millimetre values retain Gothicrock's established chart, cross-checked against published jewellery guides; UK and Japanese cross-references were reviewed against the Blue Nile chart. The result is an estimate and does not check product availability.
References inform this guide; they do not imply endorsement of Gothicrock.
