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Ring Size Chart in CM – Centimetre Ring Size Guide UK 2026

Ring Size Chart in CM (Centimetres)

The complete 2026 ring size chart in centimetres — diameter in cm, circumference in cm, UK · US · EU conversions, how to measure your finger in cm and free cm ring size calculator

📏 Diameter in cm ⭕ Circumference in cm 🇬🇧 UK Sizes A – Z+6 🇺🇸 US Sizes 1–15 🇩🇪 EU Sizes 40–76 📅 Updated 2026
👁️ Ring Size in CM — Visual Measurement Diagram

How to Measure Your Ring Size in CM — Illustrated Guide

Wrap a paper strip around your finger. Mark the overlap. Measure the length in cm. That length is your finger circumference in cm.

STEP 1 — Wrap Paper Strip Wrap strip snugly at base of ring finger Paper strip 1 STEP 2 — Mark & Remove ← Mark Measure this length = Circumference in CM Mark overlap, lay flat and measure in cm 2 STEP 3 — Use CM Ruler 0 1 2 3 4 5 6 cm e.g. 5.09 cm → UK Size N (circumference = 50.9mm) Read your result in cm then find size in chart 3 STEP 4 — Find Your Size 4 CIRCUMFERENCE IN CM 5.09 cm 🇬🇧 UK SIZE N 🇺🇸 US 6.5 · 🇩🇪 EU 51 Diameter: 1.62 cm Circ: 50.9 mm / 5.09 cm Look up result in chart below or use the calculator

📏 Printable CM Ring Gauge — Actual Size Ring Diameter Reference

Print this page at 100% (no scaling). Place your ring over each circle to find your ring's inner diameter in cm. The measurement under the matching circle is your ring's diameter in cm.

PRINT AT 100% SCALE — Place ring over circles to find diameter in cm G 1.40cm H 1.46cm J 1.53cm K 1.62cm M ♀ AVG 1.59cm N 1.70cm P 1.80cm R 1.92cm T ♂ AVG 1.98cm V 2.13cm X 2.26cm Z 2.34cm Gold border = average women's (M) Blue border = average men's (T) ⚠️ Print at 100% scale — no fit/shrink. Circles are proportional reference only.
🖨️ Print at 100% — no page scaling
♀ Gold ring = Women's average: 1.59cm diameter
♂ Blue ring = Men's average: 1.98cm diameter
1.59
📏 Women's Avg
Diameter (cm) — UK M
1.98
📏 Men's Avg
Diameter (cm) — UK T
4.99
⭕ Women's Avg
Circumference (cm)
6.22
⭕ Men's Avg
Circumference (cm)
ℹ️

Ring Size Chart in CM — 2026 Overview

Ring sizes measured in centimetres (cm) use two values: inner diameter in cm (measured straight across the widest interior point of a ring) and inner circumference in cm (the distance around the inside of the ring). Most UK and EU jewellery sizing standards use millimetres (mm), so to convert: multiply cm × 10 to get mm. The average UK women's ring size M = 1.59 cm diameter / 4.99 cm circumference. The average UK men's ring size T = 1.98 cm diameter / 6.22 cm circumference. You can measure in cm with a standard ruler, cloth tape measure or the paper strip method above.

🔄 CM ↔ MM — Quick Conversion Formulas
✖️

CM → MM (multiply)

mm = cm × 10

Example: 1.59 cm × 10 = 15.9 mm diameter → UK Size M

➗

MM → CM (divide)

cm = mm ÷ 10

Example: 49.9 mm ÷ 10 = 4.99 cm circumference → UK Size M

⭕

Diameter → Circumference

circ = diam × π

Example: 1.59 cm × 3.1416 = 4.99 cm circumference

📐

Circumference → Diameter

diam = circ ÷ π

Example: 4.99 cm ÷ 3.1416 = 1.59 cm diameter

🇺🇸

CM Diameter → US Size

US ≈ (cm − 1.18) ÷ 0.032 × 2.54

Easier: convert cm → mm diameter, then look up the chart below.

🇩🇪

CM Circumference → EU

EU = cm × 10

Example: 4.99 cm × 10 = EU 50 (circ. in mm = EU size)

🧮 Ring Size Calculator in CM

Enter your finger measurement in centimetres to find your ring size instantly

Your Ring Size
—
📊 Ring Size Chart in CM — Complete Table UK 2026
📏 CM = primary measurement
💗 Women's average highlighted
💙 Men's average highlighted
📱 Swipe right on mobile
🇬🇧 UK Size 📏 Diameter
(cm)		 ⭕ Circumference
(cm)		 📐 Diameter
(mm)		 ⭕ Circumference
(mm)		 🇺🇸 US Size 🇩🇪 EU Size 🇫🇷 French 👩👨 Type
📏 Convert cm to mm: multiply × 10
EU size = circumference in mm (same number)
French size = EU size − 40
📏 How to Measure Your Ring Finger in CM — Step by Step
1

Cut a thin strip of paper or use a cloth tape measure

Paper strips work best for measuring in cm — use plain copy paper cut to about 0.5 cm wide and 10 cm long. Alternatively, a flexible cloth/vinyl tape measure (the type used in dressmaking) already has cm markings and wraps naturally around the finger. Do not use a rigid metal ruler directly around the finger.

2

Wrap around the base of your ring finger

Wrap the paper strip or tape measure snugly around the base of the finger you intend to wear the ring on. The wrap should be firm but not tight — you should be able to slide one fingernail under it. Also check the strip can pass over the knuckle with a little resistance, as rings must pass the knuckle to reach the base.

3

Mark the overlap and measure in cm

Mark where the strip overlaps with a fine-tipped pen or pencil. Remove the strip and lay it flat against a centimetre ruler. Read the distance from the end of the strip to your mark — this is your finger circumference in cm. A typical reading will be between 4.2 cm (small finger) and 7.2 cm (large finger).

4

Find your size in the chart above

Find your circumference in cm reading in the Circumference (cm) column of the chart above. Read across to see your UK, US and EU ring size. If your measurement falls between two rows, always choose the larger size. You can also enter your cm measurement directly into the calculator above for an instant result.

5

Measure 3 times for accuracy

Finger size varies slightly throughout the day. Measure in the morning, afternoon and evening — fingers are slightly smaller in cold or morning conditions, and slightly larger in warm or evening conditions. Add the three readings and divide by 3 to get your average circumference in cm. Use this averaged cm value to find your ring size for the most comfortable all-day fit.

💡 Ring Measurement in CM — Expert Tips
  • 📏 CM vs MM for ring sizing: Most professional UK jewellers and ring size charts use millimetres (mm) as the standard unit. To use a cm measurement with any UK jewellery sizing chart, simply multiply your cm reading by 10 to get mm — e.g. 4.99 cm × 10 = 49.9 mm circumference = UK Size M. You do not need to rearrange anything; the conversion is instant.
  • 📐 Diameter vs circumference in cm: Ring gauges sold in jewellery stores measure diameter in mm. Home paper strip measurements give circumference in cm. Both are correct — use the right column in the chart for whichever one you measured. Diameter in cm will be a smaller number (e.g. 1.59 cm) than circumference in cm (e.g. 4.99 cm) for the same ring size.
  • 🌡️ Temperature affects cm measurement: Cold temperatures cause blood vessels to constrict and fingers to shrink by up to 0.3–0.5 mm in circumference (0.03–0.05 cm). Always measure at a comfortable room temperature — not immediately after coming in from the cold or after exercise. A warm-condition measurement gives the most representative all-day ring size.
  • 🔢 Round your cm reading correctly: CM measurements from a paper strip are only accurate to about ±0.1 cm (1mm). If your reading is 5.0 cm, your ring size could be UK M, N, or anywhere in between depending on reading technique. Always round up by 0.1 cm if you are between sizes, and order the larger UK size — it is far easier to resize a ring down one size than up.
  • 💍 Existing ring method in cm: If you already own a well-fitting ring, you can measure its inner diameter in cm with a ruler. Measure straight across the inside of the ring at its widest point. A reading of 1.62 cm = 16.2 mm = UK Size N. This is often more accurate than a paper strip measurement for people who already know one ring fits well.
❓ Ring Size in CM — FAQs
What is the average ring size in cm for women in the UK?▼
The average UK women's ring size in cm is UK Size M, which has an inner diameter of 1.59 cm (15.9 mm) and an inner circumference of 4.99 cm (49.9 mm). This is equivalent to US Size 6 and EU Size 50. Most UK women fall within the range of 1.55–1.65 cm diameter (UK Sizes L to N). When buying a ring as a surprise gift for a woman in the UK, Size M (1.59 cm diameter / 4.99 cm circumference) is the safest default.
What is the average ring size in cm for men in the UK?▼
The average UK men's ring size in cm is UK Size T, which has an inner diameter of 1.98 cm (19.8 mm) and an inner circumference of 6.22 cm (62.2 mm). This is equivalent to US Size 10 and EU Size 62. Most UK men fall within the range of 1.78–2.06 cm diameter (UK Sizes S to V). When buying a surprise ring for a man in the UK, Size T (1.98 cm) is the safest default.
How do I convert my ring circumference in cm to a UK ring size?▼
Enter your circumference in cm into the calculator above and select "Circumference in CM" — it will instantly show your UK, US and EU ring size. Alternatively, multiply your cm measurement by 10 to convert to mm, then look up the circumference (mm) column in the chart. For example: 4.99 cm × 10 = 49.9 mm = UK Size M. The EU size is also simply your circumference in mm (49.9 mm ≈ EU Size 50).
Is it better to measure ring size in cm or mm?▼
For most home measurements, either cm or mm works — the only practical difference is which unit your ruler uses. However, professional ring sizing in the UK uses millimetres (mm) as the standard unit. Because a full UK ring size increment is only about 1.25–1.6 mm, measuring in mm allows for more precise readings than cm where each 0.1 cm = 1 mm increment. If your ruler has both mm and cm markings, use the mm side for maximum precision when measuring your ring size at home.
My circumference in cm is between two sizes — what should I do?▼
Always choose the larger size when your cm measurement falls between two ring sizes. A ring that is marginally too loose can be worn with a ring size adjuster (a small silicone or metal insert available from any UK jeweller) for a few pounds. A ring that is too tight is uncomfortable, can be difficult to remove, and is more expensive to resize. If your reading is exactly halfway between two UK sizes, most jewellers offer half-sizes (e.g. J½, K½) which split the difference precisely.
Can I measure a ring in cm to find its size?▼
Yes — measuring an existing ring's inner diameter in cm is one of the most accurate home methods. Place the ring on a flat surface, then lay a cm ruler across the inside of the ring, measuring straight across the widest interior point. Read the diameter in cm. For example, a measurement of 1.62 cm = 16.2 mm = UK Size N / US 6.5 / EU 51. Enter this value into the calculator above (selecting "Diameter in CM") for an instant conversion to all ring size systems.

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