Japan to AU Ring Size Conversion – Japanese to Australian Ring Size Chart

Japan to AU Ring Size Conversion

Instantly convert Japanese ring sizes to Australian (UK/AU) letter sizes — complete chart with US, EU, diameter in mm, circumference, and a free Japan ↔ AU calculator

🇯🇵 Japan Numbers → 🇦🇺 AU Letters 📊 Japan 1 – 33 🇬🇧 AU A – Z+6 🇺🇸 US · 🇪🇺 EU · mm 🧮 Free Converter

🇯🇵

1–33

Japan Ring
Size Range

🇦🇺

A–Z+6

AU/UK Letter
Size Range

👩

JP 13

Avg Women's
Japan Size (= AU N)

👨

JP 20

Avg Men's
Japan Size (= AU T)

🔄

Japan vs AU Ring Size Systems

🇯🇵

Japanese Ring Sizing

Uses whole and half numbers
Range: 1 – 33 (also ½ sizes)
Standard: JCS (Japanese Industrial Standard)
Also used in: China, South America
Based on: Inner circumference (mm)

Number-Based System

⇄

🇦🇺

Australian Ring Sizing

Uses alphabet letters
Range: A – Z+6 (also ½ sizes)
Standard: Same as UK (British Standard)
Also used in: UK, Ireland, South Africa
Based on: Inner circumference (mm)

Letter-Based System

ℹ️

The AU (Australian) ring size system is identical to the UK system. Both use letter codes starting from A. When you see "UK size" on a ring, the same letter applies directly in Australia — no additional conversion is needed between the two.

🧮

Japan ↔ AU Ring Size Converter

Select your Japanese ring size to see your AU (UK), US, EU and mm equivalent

🇯🇵 Japan

—

Japan / China

🇦🇺 AU / UK

—

Australia / UK

🇺🇸 US

—

US / Canada

🇪🇺 EU

—

Europe

📊

Full Japan to AU Ring Size Chart

👩 Women's (JP 5–15)

👨 Men's (JP 15–27)

📋 Full Chart

👩

Women's Japanese ring sizes typically range from Japan 5 to Japan 15, corresponding to AU F to AU O. The most popular women's Japanese size is Japan 13 (= AU N).

Japan Size	AU / UK	US Size	EU Size	Circumference (mm)	Diameter (mm)
5	F	3	44	44.1 mm	14.0 mm
5.5	F½	3¼	44½	44.7 mm	14.2 mm
6	G	3½	45	45.4 mm	14.4 mm
7	G½	3¾	46	46.0 mm	14.6 mm
8	H	4	46½	46.7 mm	14.9 mm
9	I	4½	48	48.0 mm	15.3 mm
10	J	5	49	49.2 mm	15.7 mm
11	K	5½	50½	50.5 mm	16.1 mm
12	L	6	51½	51.8 mm	16.5 mm
13 ⭐	M	6½	53	53.1 mm	16.9 mm
14 ⭐	N	7	54	54.4 mm	17.3 mm
15	O	7½	55½	55.7 mm	17.7 mm

⭐ Most popular women's: JP 13–14 = AU M–N

🟡 Highlighted = most ordered

👨

Men's Japanese ring sizes typically range from Japan 15 to Japan 27, corresponding to AU O to AU Z. The most popular men's Japanese size is Japan 20 (= AU T).

Japan Size	AU / UK	US Size	EU Size	Circumference (mm)	Diameter (mm)
15	O	7½	55½	55.7 mm	17.7 mm
16	P	8	57	57.0 mm	18.1 mm
17	Q	8½	58	58.3 mm	18.5 mm
18	R	9	59½	59.6 mm	19.0 mm
19	S	9½	61	60.9 mm	19.4 mm
20 ⭐	T	10	62	62.2 mm	19.8 mm
21	T½	10¼	62½	62.8 mm	20.0 mm
22	U	10½	63½	63.5 mm	20.2 mm
23	V	11	64½	64.7 mm	20.6 mm
24	W	11½	66	66.0 mm	21.0 mm
25	X	12	67	67.3 mm	21.4 mm
26	Y	12½	68½	68.6 mm	21.8 mm
27	Z	13	69½	69.9 mm	22.3 mm

⭐ Most popular men's: JP 20 = AU T

🟡 Highlighted = most ordered

📋

Complete Japan to AU conversion from Japan 1 to Japan 33. Sizes marked with ~approx are half-sizes that are approximated conversions — exact standardised equivalents may vary slightly between jewellers.

Japan	AU / UK	US	EU	Circumference	Diameter
1	B	1	38½	38.9 mm	12.4 mm
1.5	B½ ~approx	1¼	39½	39.5 mm	12.6 mm
2	C	1½	40	40.2 mm	12.8 mm
2.5	C½ ~approx	1¾	40½	40.8 mm	13.0 mm
3	D	2	41½	41.5 mm	13.2 mm
3.5	D½ ~approx	2¼	42	42.1 mm	13.4 mm
4	E	2½	43	42.8 mm	13.6 mm
4.5	E½ ~approx	2¾	43½	43.4 mm	13.8 mm
5	F	3	44	44.1 mm	14.0 mm
5.5	F½	3¼	44½	44.7 mm	14.2 mm
6	G	3½	45	45.4 mm	14.4 mm
7	G½	3¾	46	46.0 mm	14.6 mm
8	H	4	46½	46.7 mm	14.9 mm
8.5	H½ ~approx	4¼	47	47.3 mm	15.1 mm
9	I	4½	48	48.0 mm	15.3 mm
9.5	I½ ~approx	4¾	48½	48.6 mm	15.5 mm
10	J	5	49	49.2 mm	15.7 mm
10.5	J½ ~approx	5¼	49½	49.9 mm	15.9 mm
11	K	5½	50½	50.5 mm	16.1 mm
11.5	K½ ~approx	5¾	51	51.2 mm	16.3 mm
12	L	6	51½	51.8 mm	16.5 mm
12.5	L½ ~approx	6¼	52	52.5 mm	16.7 mm
13 ⭐	M	6½	53	53.1 mm	16.9 mm
13.5	M½ ~approx	6¾	53½	53.8 mm	17.1 mm
14 ⭐	N	7	54	54.4 mm	17.3 mm
14.5	N½ ~approx	7¼	55	55.1 mm	17.5 mm
15	O	7½	55½	55.7 mm	17.7 mm
15.5	O½ ~approx	7¾	56	56.4 mm	17.9 mm
16	P	8	57	57.0 mm	18.1 mm
16.5	P½ ~approx	8¼	57½	57.6 mm	18.3 mm
17	Q	8½	58	58.3 mm	18.5 mm
17.5	Q½ ~approx	8¾	58½	58.9 mm	18.7 mm
18	R	9	59½	59.6 mm	19.0 mm
18.5	R½ ~approx	9¼	60	60.2 mm	19.2 mm
19	S	9½	61	60.9 mm	19.4 mm
19.5	S½ ~approx	9¾	61½	61.5 mm	19.6 mm
20 ⭐	T	10	62	62.2 mm	19.8 mm
21	T½	10¼	62½	62.8 mm	20.0 mm
22	U	10½	63½	63.5 mm	20.2 mm
22.5	U½ ~approx	10¾	64	64.1 mm	20.4 mm
23	V	11	64½	64.7 mm	20.6 mm
23.5	V½ ~approx	11¼	65	65.4 mm	20.8 mm
24	W	11½	66	66.0 mm	21.0 mm
24.5	W½ ~approx	11¾	66½	66.7 mm	21.2 mm
25	X	12	67	67.3 mm	21.4 mm
25.5	X½ ~approx	12¼	68	68.0 mm	21.6 mm
26	Y	12½	68½	68.6 mm	21.8 mm
26.5	Y½ ~approx	12¾	69	69.2 mm	22.0 mm
27	Z	13	69½	69.9 mm	22.3 mm
27.5	Z½ ~approx	13¼	70	70.5 mm	22.4 mm
28	Z+1	13½	71	71.2 mm	22.7 mm
29	Z+2	14	72½	72.5 mm	23.1 mm
30	Z+3	14½	73½	73.7 mm	23.5 mm
31	Z+4	15	74½	74.8 mm	23.8 mm
32	Z+5	15½	76	76.0 mm	24.2 mm
33	Z+6	16	76½	76.9 mm	24.5 mm

⭐ Women's avg: JP 13–14 = AU M–N

⭐ Men's avg: JP 20 = AU T

🇬🇧 AU = UK sizing

~ = approximated half-size

🔬

Key Differences Between the Systems

🔢

Japan Uses Numbers, AU Uses Letters

Japan's ring sizing system uses sequential numbers starting from 1 (smallest). Australia (identical to the UK) uses alphabet letters from A upward. The two systems both measure inner finger circumference in mm but present the result differently.

🌏

Japan Sizes Also Used in China & South America

The Japanese numerical sizing system is also used in China and South America. If you are buying from a Chinese jeweller or South American brand, their size numbers are equivalent to Japanese sizes and convert directly to AU letters using this chart.

📐

Half Sizes Are More Common in Japan

Japanese sizing frequently includes half-sizes (e.g., Japan 13.5, 14.5) that do not have standardised direct equivalents in the AU/UK letter system. These are shown as approximate (~ approx) conversions in the chart and calculator above.

🇬🇧

AU and UK Are Identical

The Australian ring sizing system is exactly the same as the UK system — both use the same letter codes. A ring sized "UK N" is the same as "AU N." When you use this Japan → AU chart, the result applies directly to UK-sold rings without any additional conversion.

💡

Shopping Tips for Japanese Rings

🛍️Check which standard the Japanese brand uses: Most Japanese jewellers (e.g., NIWAKA, Tasaki, Mikimoto) follow the JCS (Japanese Industrial Standard) number system. However, some high-end boutiques sell using EU or US sizing — always verify the size system before ordering.
⬆️If between sizes, size up: Japanese sizing steps between whole numbers can straddle two AU letters. If your converted AU size falls between two letters, choose the larger letter (e.g., choose N rather than M½) to ensure a comfortable fit.
🌡️Measure in the evening: Whether measuring for a Japanese or Australian-sized ring, always measure your finger between 6pm and 9pm when your finger is at its natural daily maximum size. This prevents accidentally ordering too small.
🔧Japanese rings are resizable: Most Japanese gold and platinum rings can be resized by a jeweller in Australia without issue. However, rings with engraving, stone pave, or full-circumference patterns may have limited resize options — confirm with the jeweller before purchasing.
📦Order direct from Japan: Many Japanese jewellers (e.g., NIWAKA, Ete, 4°C) offer international shipping. Use this conversion chart to select the correct AU-equivalent size when filling in their size selector, which will be displayed in Japanese numbers.

❓

Frequently Asked Questions

What is Japan size 13 in Australian ring size? ▾

Japan size 13 equals AU / UK size M, which is US 6½ and EU 53. It has an inner circumference of approximately 53.1 mm and an inner diameter of 16.9 mm. This is one of the most popular women's ring sizes in Japan.

What is Japan size 14 in Australian ring size? ▾

Japan size 14 equals AU / UK size N, which is US 7 and EU 54. It has an inner circumference of approximately 54.4 mm and inner diameter of 17.3 mm. Japan 14 / AU N is the average women's ring size in both Japan and Australia.

What is Japan size 20 in Australian ring size? ▾

Japan size 20 equals AU / UK size T, which is US 10 and EU 62. It has an inner circumference of approximately 62.2 mm and inner diameter of 19.8 mm. Japan 20 / AU T is the average men's ring size in both systems.

Is AU ring sizing the same as UK ring sizing? ▾

Yes — Australian and UK ring sizes are identical. Both use the same alphabet letter system starting from A. When converting from a Japanese ring size to AU using this chart, the result applies directly to UK ring sizes as well. No additional conversion between AU and UK is needed.

Are Chinese ring sizes the same as Japanese ring sizes? ▾

Yes — Chinese ring sizes use the same number system as Japanese ring sizes. Both China and Japan (as well as South America) use the same numerical sizing standard. A ring labelled "China size 14" or "Japan size 14" both equal AU size N. You can use this chart directly for Chinese ring size conversions to AU.

What if my Japanese ring size is a half-size (e.g. 13.5)? ▾

Half Japanese sizes (e.g. 13.5, 14.5) do not have exact standardised AU/UK equivalents — they fall between two AU letter sizes. Japan 13.5 converts to approximately AU M½ (between M and N). If a half-letter AU size is not available from your jeweller, choose the next full letter size up (e.g., AU N rather than M) for a comfortable fit.

How do I convert my AU ring size back to Japanese sizing? ▾

Simply find your AU/UK letter in the AU/UK column of the chart above and read across to the Japan column. For example: AU N = Japan 14, AU T = Japan 20, AU O = Japan 15. For AU half-sizes (e.g., AU N½), the nearest Japanese equivalent is the next whole size up (Japan 14.5 ≈ AU N½).

🇯🇵 JP 13 = AU M

🇯🇵 JP 14 = AU N (Women's avg)

🇯🇵 JP 20 = AU T (Men's avg)

🇦🇺 AU = UK sizing

🇨🇳 China = Japan sizing