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Size Converter — Ring, Shoe, Clothing

Convert ring, shoe, clothing and bra sizes between South Korea, US, Japan and EU charts, and measure a ring on screen.

Korean size

e.g. 10 or 10.5

Korea (KS): No. 12
US · Canada: 7.5
Japan: 15号
UK · Australia: O½
Europe (ISO): 56
Inner diameter · circumference: 17.7mm · 55.5mm

Measure a ring at actual size on screen

Calibrate your screen. Hold a credit or debit card against the box below and adjust until the box matches the card exactly (card size 85.60×53.98 mm, ISO/IEC 7810 ID-1).
Place your ring. Put a ring you own on the circle and change the size until the circle’s edge lines up with the ring’s inner edge.
No. 10
Korea (KS)
No. 10
US · Canada
6.5
Japan
13号
UK · Australia
M½
Europe (ISO)
53
Inner diameter · circumference
17.0mm · 53.4mm

Until you calibrate with a card, the circle may not match real size. Recalibrate if you change the browser zoom. For thick bands or large knuckles, go half a size up.

Korean KS ring size chart (No. 1–30)

Korea	Inner diameter	Circumference	US	Japan	UK
No. 1	14.0	44.0	3	4	F
No. 2	14.3	45.0	3.25	5	G
No. 3	14.7	46.1	3.75	6	H
No. 4	15.0	47.1	4.25	7	H½
No. 5	15.3	48.2	4.5	8	I½
No. 6	15.7	49.2	5	9	J½
No. 7	16.0	50.3	5.5	10	K
No. 8	16.3	51.3	5.75	11	L
No. 9	16.7	52.4	6.25	12	M
No. 10	17.0	53.4	6.5	13	M½
No. 11	17.3	54.5	7	14	N½
No. 12	17.7	55.5	7.5	15	O½
No. 13	18.0	56.5	7.75	16	P
No. 14	18.3	57.6	8.25	17	Q
No. 15	18.7	58.6	8.75	18	R
No. 16	19.0	59.7	9	19	S
No. 17	19.3	60.7	9.5	20	S½
No. 18	19.7	61.8	10	21	T½
No. 19	20.0	62.8	10.25	22	U½
No. 20	20.3	63.9	10.75	23	V
No. 21	20.7	64.9	11	24	W
No. 22	21.0	66.0	11.5	25	X
No. 23	21.3	67.0	12	26	X½
No. 24	21.7	68.1	12.25	27	Y½
No. 25	22.0	69.1	12.75	28	Z½
No. 26	22.3	70.2	13.25	29	Z+1
No. 27	22.7	71.2	13.5	30	Z+2
No. 28	23.0	72.3	14	31	Z+3
No. 29	23.3	73.3	14.5	32	Z+3½
No. 30	23.7	74.4	14.75	33	Z+4½

All conversions are approximate. Rings: EU = inner circumference (ISO 8653); US = inner diameter 11.63 mm + 0.8128 mm × size; Japan = inner diameter from 13 mm in 1/3 mm steps; Korea follows the 2019 KS standard chart (size 1 = 44.0 mm circumference) and may differ by 1–2 sizes between shops. Shoes convert foot length (mm) the way sneaker brand charts do. Inputs are not saved; only the screen calibration is stored in this browser if you choose.

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How to use

Everything you enter is processed only in this browser.

Choose ring, shoes, clothing or bra
Enter the size you know and it’s converted to other countries’ systems
For rings, calibrate the screen with a card, then hold your ring against it

How it works and good to know

Rings: Europe = inner circumference (ISO 8653); US = inner diameter 11.63 mm + 0.8128 mm × size; Japan = inner diameter from 13 mm in 1/3 mm steps; Korea follows the 2019 Korean KS standard chart (size 1 = 44.0 mm circumference). On-screen measuring calibrates the screen scale with a credit card (85.60 × 53.98 mm, ISO/IEC 7810 ID-1), and only the calibration is saved in this browser. Shoes are converted by foot length (mm) the way common sneaker brand charts do, and clothing and bras with conversion charts commonly used in Korea. All conversions are approximate and can vary by brand.

Size Converter — Ring, Shoe, Clothing

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