Ring Size Chart in CM – Centimeter Ring Size Guide 2026

Ring Size Chart in CM

Measure your ring size in centimetres — complete circumference and diameter chart in CM with US, UK, AU/NZ, EU, and Japan size conversions, plus a free CM ring size calculator

📏 Circumference in CM 🇺🇸 US · 🇬🇧 UK · 🇦🇺 AU · 🇪🇺 EU · 🇯🇵 JP 👩 Women's & 👨 Men's Sizes 🧮 Free CM Calculator 💒 Engagement Ring Guide

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5.44 cm

Average Women's
Ring Circumference

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6.35 cm

Average Men's
Ring Circumference

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1.73 cm

Average Ring
Finger Diameter

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Universal Metric
Measurement System

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Why Use Centimetres (CM) for Ring Sizing?

Measuring your ring size in centimetres (CM) gives you a universal metric measurement that works across all international sizing systems — US numbers, UK letters, EU numbers, AU/NZ letters, and Japanese sizes. The average women's ring finger circumference is 5.44 cm (US size 7 / UK N / EU 55 / AU N) and the average men's is 6.35 cm (US size 10½ / UK U / EU 64). To find your size, wrap a strip of paper or string around your finger, measure the length in centimetres with a ruler, and match it to the chart below. Always measure at room temperature in the evening for the most accurate reading.

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Typical Ring Size in CM — By Finger

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Thumb

5.63–6.60 cm

US: 7½–10 / UK: O–T

The widest finger. Thumb circumferences typically range from 5.63 cm to 6.60 cm. Always measure your specific thumb as sizes vary greatly by individual. Men's thumbs often exceed 6.5 cm.

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Index Finger

5.14–5.70 cm

US: 6–8 / UK: L–P

Typically half a size larger than the ring finger. Index circumference is usually 5.14–5.70 cm for women. Confirm on this exact finger — do not assume it matches your ring finger measurement.

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Middle Finger

5.14–5.70 cm

US: 6–8 / UK: L–P

Similar in girth to the index finger at 5.14–5.70 cm average. Rings for the middle finger may need slight adjustments versus the ring finger. Always measure the actual finger the ring will be worn on.

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Ring Finger

4.91–5.57 cm

US: 5–7½ / UK: J–O

The most commonly sized finger. Average women's ring finger circumference is 5.44 cm (US 7). Average men's is 5.95–6.23 cm (US 9–10). Always measure the specific hand the ring will be worn on.

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Pinky Finger

4.40–4.91 cm

US: 3–5 / UK: F–J

The smallest finger. Pinky circumferences usually range from 4.40–4.91 cm for women. Petite pinky sizes can be as small as 4.40 cm (US 3 / UK F). Always confirm with your jeweller for sizes below 4.65 cm.

💡 Dominant hand fingers are ~0.2 cm larger in circumference

💡 Always measure the exact finger and hand the ring will be worn on

💡 Evening indoor measurements give the most accurate result

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Ring Size Calculator in CM

Enter your finger measurement in centimetres to find your ring size

Your Ring Size

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Women's Ring Size Chart in CM — Full Reference

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Most Common Women's Ring Size: 5.18–5.57 cm Circumference

The highlighted rows represent the most commonly purchased women's ring sizes worldwide. A circumference of 5.44 cm (US 7 / UK N / AU N / EU 55 / JP 14) is the most popular single size for women internationally. Petite women typically measure 4.40–5.05 cm; average women 5.05–5.70 cm; and larger sizes 5.70 cm and above. Data sourced from Vermont Gem Lab and Tresor Jewelry CM ring size standards.

Circumference (CM)	Circumference (MM)	Diameter (CM)	🇺🇸 US Size	🇬🇧 UK / 🇦🇺 AU	🇪🇺 EU Size	🇯🇵 Japan	Fit Range
4.40 cm	44.0 mm	1.40 cm	3	F	44	4	Petite
4.53 cm	45.3 mm	1.44 cm	3½	G	46	5½	Petite
4.65 cm	46.5 mm	1.48 cm	4	H	47	7	Petite
4.78 cm	47.8 mm	1.52 cm	4½	I	49	8	Small
4.91 cm	49.1 mm	1.56 cm	5	J	50	9	Popular ⭐
5.05 cm	50.5 mm	1.61 cm	5½	K	51	10½	Popular ⭐
5.18 cm	51.8 mm	1.65 cm	6	L	52	12	Most Common 🏆
5.30 cm	53.0 mm	1.69 cm	6½	M	54	13	Most Common 🏆
5.44 cm ⭐	54.4 mm	1.73 cm	7	N	55	14	Average Women's 🏆
5.57 cm	55.7 mm	1.77 cm	7½	O	56	15	Popular ⭐
5.70 cm	57.0 mm	1.81 cm	8	P	57	16	Popular ⭐
5.82 cm	58.2 mm	1.85 cm	8½	Q	59	17	Above Avg
5.95 cm	59.5 mm	1.90 cm	9	R	60	18	Large
6.08 cm	60.8 mm	1.94 cm	9½	S	61	19	Large
6.21 cm	62.1 mm	1.98 cm	10	T	62	20	XL

🏆 5.44 cm = Average women's ring circumference worldwide

⭐ 4.91–5.70 cm = Most popular women's range

🟡 Highlighted = Most common women's sizes

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Men's Ring Size Chart in CM — Full Reference

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Most Common Men's Ring Size: 6.23–6.49 cm Circumference

Men's ring sizes typically range from 5.70 cm to 7.28 cm in circumference. A circumference of 6.35 cm (US 10½ / UK U / AU U / EU 64 / JP 22) is the most common men's ring size. Most men fall between 5.95 cm and 6.49 cm. Data sourced from Tresor Jewelry and Vermont Gem Lab CM ring size guides.

Circumference (CM)	Circumference (MM)	Diameter (CM)	🇺🇸 US Size	🇬🇧 UK / 🇦🇺 AU	🇪🇺 EU Size	🇯🇵 Japan	Fit Range
5.70 cm	57.0 mm	1.81 cm	8	P	57	16	Small Men's
5.82 cm	58.2 mm	1.85 cm	8½	Q	59	17	Small Men's
5.95 cm	59.5 mm	1.90 cm	9	R	60	18	Popular Men's
6.09 cm	60.9 mm	1.94 cm	9½	S	61	19	Popular Men's
6.23 cm	62.3 mm	1.98 cm	10	T	62	20	Most Common 🏆
6.35 cm ⭐	63.5 mm	2.02 cm	10½	U	64	22	Average Men's 🏆
6.49 cm	64.9 mm	2.07 cm	11	V	65	23	Popular Men's
6.61 cm	66.1 mm	2.10 cm	11½	W	67	24	Large
6.75 cm	67.5 mm	2.14 cm	12	X	68	25	Large
6.88 cm	68.8 mm	2.19 cm	12½	Y	69	26	XL
7.02 cm	70.2 mm	2.23 cm	13	Z	70	27	XL
7.14 cm	71.4 mm	2.27 cm	13½	Z+1	72	28	XXL
7.28 cm	72.8 mm	2.32 cm	14	Z+2	73	29	XXL

🏆 6.35 cm = Average men's ring circumference worldwide

⭐ 5.95–6.49 cm = Most popular men's range

🟦 Blue highlighted = Most common men's sizes

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Average Ring Size in CM — By Country

Country / Region	Women's Average (CM)	Men's Average (CM)	Local Size	US Equivalent
🇺🇸 USA & Canada	5.44 cm	6.35 cm	US 7 / US 10½	US 7 / US 10½
🇬🇧 United Kingdom	5.18–5.30 cm	6.23–6.35 cm	UK L–M / UK T–U	US 6–6½ / US 10–10½
🇦🇺 Australia / 🇳🇿 NZ	5.25–5.44 cm	6.23–6.35 cm	AU M–N / AU T–U	US 6¼–7 / US 10–10½
🇪🇺 Continental Europe	5.18–5.44 cm	6.21–6.49 cm	EU 52–55 / EU 62–65	US 6–7 / US 10–11
🇯🇵 Japan	5.00–5.18 cm	5.95–6.23 cm	JP 9–12 / JP 18–20	US 5½–6 / US 9–10
🌏 Asia (General)	4.40–5.18 cm	5.82–6.35 cm	US 3–6 / US 8½–10½	US 3–6 / US 8½–10½

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How to Measure Ring Size in CM at Home

Method 1 — Paper Strip in CM (Most Accurate)

Cut a thin strip of paper or use non-stretch thread

Cut a strip of plain paper approximately 5 mm wide and 10–12 cm long. Non-stretch thread, dental floss, or a thin fabric ribbon also work well. Avoid elastic or stretchy materials as they give an undersized result.

Warm your hands and wrap indoors at room temperature

Cold fingers give a falsely small measurement. Warm your hands for 10–15 minutes indoors, then wrap the strip snugly around the base of the finger. Also test over the knuckle — the ring must slide over it comfortably. Measure in the evening when fingers are at their largest.

Mark the overlap point with a pen

Mark where the strip overlaps itself precisely with a fine pen or pencil. The distance from the start of the strip to your mark is your finger circumference in centimetres.

Measure the length in centimetres with a ruler

Lay the strip flat on a ruler and read the measurement carefully in centimetres. For example, a reading of 5.44 cm corresponds to US size 7 / UK N / AU N / EU 55. Enter this value into the calculator above for an instant full conversion.

Repeat 3 times and use the middle value

Take at least three measurements at different times of day and use the median (middle) value. Small variations of 0.05–0.10 cm are completely normal. If your measurement falls between two rows in the chart, always choose the larger size for a comfortable fit.

Method 2 — Existing Ring Diameter in CM

Choose a well-fitting ring worn on the correct finger

Use a ring that fits comfortably on the specific finger the new ring will be worn on. A ring from a different finger will give an inaccurate result as sizes vary significantly between fingers and between hands.

Measure the inner diameter in centimetres

Place the ring on a ruler and measure straight across the inside opening in centimetres. For example, 1.73 cm inner diameter = 5.44 cm circumference = US 7 / UK N / AU N. Take two readings at different angles and average them.

Use the Diameter column in the chart or the calculator above

Match your diameter value in centimetres to the "Diameter (CM)" column in the charts above, or select "Diameter (cm)" in the calculator for an instant result with all international size equivalents.

📐 Key CM Formulas

Diameter (cm) → Circumference (cm)

Circumference = Diameter × π (3.14159)

Example: 1.73 cm × 3.14159 = 5.44 cm → US 7 / UK N / AU N / EU 55

Circumference (cm) → Diameter (cm)

Diameter = Circumference ÷ π (3.14159)

Example: 5.44 cm ÷ 3.14159 = 1.73 cm → US 7 / UK N / AU N / EU 55

CM → MM

Millimetres = Centimetres × 10

Example: 5.44 cm × 10 = 54.4 mm → US 7 / UK N / AU N / EU 55

Inches → CM

Centimetres = Inches × 2.54

Example: 2.14″ × 2.54 = 5.44 cm → US 7 / UK N / AU N / EU 55

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Factors That Affect Ring Size in CM

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Temperature

Heat causes fingers to swell by 0.10–0.20 cm in circumference; cold causes them to shrink by the same amount. Always measure indoors at room temperature for your true neutral measurement. Hot days and cold winters both shift your CM reading away from your true size.

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Time of Day

Fingers are smallest in the morning (typically 0.05–0.10 cm smaller) and largest in the evening. An evening measurement at room temperature gives the most comfortable all-day ring fit. This applies regardless of which CM measurement unit you use.

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Dominant Hand

The dominant hand's ring finger is typically 0.10–0.20 cm larger in circumference than the non-dominant hand's equivalent finger. Always measure the specific finger and hand the ring will be worn on — do not transfer measurements between hands.

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Exercise & Activity

Hands swell during and after physical activity, temporarily increasing circumference by 0.15–0.25 cm. Always measure after at least a 30-minute rest indoors, not directly after exercise, for an accurate everyday ring size in centimetres.

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Pregnancy & Hormones

Fluid retention during pregnancy can increase ring circumference by 0.32–0.64 cm (1–2 sizes). This typically reverses after delivery. Avoid permanently sizing up during pregnancy — plan for a post-pregnancy resize or use a ring adjuster in the interim.

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Band Width

Wide bands (over 6 mm) feel tighter than slim bands at the same inner circumference. For any ring wider than 6 mm, add approximately 0.16 cm to your measured circumference (half a US size up) to ensure a comfortable fit over the knuckle and at the finger base.

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Expert Tips for Measuring Ring Size in CM

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Use a metric ruler, not a tape measure with imperial markings. A flat metal or plastic ruler with clear centimetre markings gives the most accurate strip measurement. A tape measure can work if it clearly shows centimetre graduations, but ensure it is not stretched or kinked. A reading error of just 0.05 cm can shift your ring size by half a US size.
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Measure in the evening for the most comfortable fit. Fingers are at their largest in the evening after a day's activity. An evening measurement in centimetres reflects the maximum your finger will be throughout a normal day, giving you the most comfortable year-round fit. Morning readings run approximately 0.05–0.10 cm smaller than true size.
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Measure three times and use the median value. Take three measurements across different times of day and use the middle reading in centimetres. Small variation (0.05–0.10 cm) between readings is completely normal. Only large variation (over 0.15 cm) suggests a measurement error worth investigating.
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Round up if your CM measurement falls between chart rows. If your circumference reading falls between two rows in the chart, always choose the row with the larger CM value. A slightly larger ring is comfortable and can be adjusted — a ring that is too small is unwearable without resizing. This is especially important for wide-band rings where an additional 0.16 cm (half size up) is recommended.
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Share your CM measurement when ordering from international jewellers. Your circumference in centimetres (e.g., 5.44 cm) is understood universally by jewellers in the US, UK, Europe, Japan, and Australia, regardless of their local sizing system. It eliminates conversion errors entirely. Always include both CM circumference and CM diameter in any international custom order.
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Buying a surprise gift? Use 5.44 cm as the default women's starting point. A circumference of 5.44 cm (US 7 / UK N / AU N / EU 55) is the average women's ring size worldwide and the most commonly stocked size at jewellers globally. For men, 6.35 cm (US 10½ / UK U) is the global average. Both are safe starting points for a surprise purchase as most jewellers offer a first free resize for plain metal bands.
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Wide bands: always add 0.16 cm to your measured circumference. Rings wider than 6 mm press against more of the finger and feel tighter than slim bands at the same inner circumference. Add 0.16 cm (equivalent to half a US size) to your standard measurement when ordering any ring with a wide band for a comfortable fit that slides over the knuckle without force.

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Frequently Asked Questions

What is the average ring size in CM for women? ▾

The average ring size for women is 5.44 cm in circumference (54.4 mm), which corresponds to US size 7, UK/AU size N, EU size 55, and Japan size 14. The diameter equivalent is 1.73 cm. Most women fall between 4.91 cm (US 5) and 5.70 cm (US 8) in circumference. Petite hands are typically under 5.05 cm, and larger hands are usually 5.70 cm and above.

What is the average ring size in CM for men? ▾

The average ring size for men is 6.35 cm in circumference (63.5 mm), which equals US size 10½, UK/AU size U, EU size 64, and Japan size 22. The diameter equivalent is 2.02 cm. Most men's ring sizes range from 5.95 cm (US 9) to 6.49 cm (US 11) in circumference. Men with smaller hands typically measure 5.70–6.09 cm, while those with larger hands measure 6.75–7.28 cm.

How do I measure my ring size in CM at home? ▾

The easiest home method is the paper strip technique: (1) Cut a strip of paper about 5 mm wide and 10 cm long. (2) Warm your hands indoors to room temperature. (3) Wrap the strip snugly around the base of the finger where the ring will sit. (4) Mark where the strip overlaps with a fine pen. (5) Measure the length from start to mark with a ruler in centimetres. (6) Match the value to the Circumference (CM) column in the chart above, or enter it into the calculator. The result gives you US, UK, AU, EU, and Japan sizes instantly.

How do I convert CM to US ring size? ▾

How do I convert CM to UK or Australian ring size? ▾

Key CM to UK/AU conversions: 4.40 cm = F | 4.53 cm = G | 4.65 cm = H | 4.78 cm = I | 4.91 cm = J | 5.05 cm = K | 5.18 cm = L | 5.30 cm = M | 5.44 cm = N | 5.57 cm = O | 5.70 cm = P | 5.82 cm = Q | 5.95 cm = R | 6.08 cm = S | 6.21 cm = T | 6.35 cm = U | 6.49 cm = V | 6.61 cm = W | 6.75 cm = X | 7.02 cm = Z. UK and Australian sizing uses the same letter system with identical measurements.

Is it better to measure in CM or MM for ring sizing? ▾

Both CM and MM work equally well — MM simply has more decimal places (e.g., 54.4 mm vs 5.44 cm) which can be slightly more precise for borderline measurements. Most European jewellers use MM as their standard; many online guides use CM as it is easier to read on a standard ruler. When sharing measurements with an international jeweller, providing both values (e.g., "5.44 cm / 54.4 mm circumference, 1.73 cm / 17.3 mm diameter") eliminates any ambiguity about units.

What if my CM measurement falls between two sizes in the chart? ▾

If your circumference in CM falls between two rows in the chart, always choose the larger size. A ring that is slightly large is comfortable and can be kept in place with a ring adjuster or professionally resized down. A ring that is too small cuts off circulation, is uncomfortable, and cannot be worn until resized. For wide-band rings (over 6 mm wide), add 0.16 cm to your measured circumference before consulting the chart to ensure the ring slides over your knuckle comfortably.