How to Convert Ring Sizes - Ringchart.co.uk

How to Convert Ring Sizes – Complete 2026 Guide

The complete guide to converting ring sizes in 2026 — how to convert between UK, US, EU, AU and CA ring sizes step by step. Five conversion methods explained, full master chart, string method, diameter method, existing ring method, free multi-system calculator, and all conversion formulas

🇬🇧 UK ↔ 🇺🇸 US 🇪🇺 EU ↔ 🇬🇧 UK 🇦🇺 AU ↔ 🇬🇧 UK 🇨🇦 CA ↔ 🇬🇧 UK 📐 mm → Any Size 5 Conversion Methods 🧮 Free Calculator ✅ 2026 Updated

🌍 Major Ring
Sizing Systems

2 Pairs

✅ AU=UK · CA=US
No conversion needed

UK N

👩 Women's avg
= US 6.5 = EU 52

UK T

👨 Men's avg
= US 9.5 = EU 61

🔄

How to Convert Ring Sizes — The Essentials

Converting ring sizes involves three steps: (1) identify which sizing system your known size is in, (2) measure or look up the equivalent circumference or diameter in mm, and (3) use a conversion chart or calculator to find the target system's size. Two shortcuts save time: Australian sizes equal UK sizes exactly (no conversion), and Canadian sizes equal US sizes exactly (no conversion). All other combinations — UK↔US, UK↔EU, US↔EU — require the chart below. The free calculator on this page converts any size to all five systems in one click.

The Fastest Way to Convert Any Ring Size

The single most reliable conversion method is to find the mm inner circumference of the ring — because circumference is a universal measurement that converts directly into any sizing system. Measure a finger with string, measure an existing ring with a ruler, or use a known EU size (which equals circumference in mm directly). Then find that circumference in the chart below and read any system's equivalent in the same row.

📐 mm is the universal bridge 🇪🇺 EU = circumference in mm ⬆️ Between sizes — always go larger

📋 5 Ways to Convert Ring Sizes – Step by Step 2026

📏

Method 1 — String or Paper Strip (Measure Finger)

Step 1: Cut a thin strip of paper ~10cm long, or use a piece of string.
Step 2: Wrap it snugly around the base of the ring finger (not too tight — it should slide over the knuckle).
Step 3: Mark where the paper overlaps to form a complete circle.
Step 4: Measure the length to the mark in millimetres — that is your circumference.
Step 5: Find that mm circumference in the master chart below → read your UK, US, EU or AU equivalent in the same row.
Best time to measure: 5–9pm when fingers are at their largest natural daytime size.

✅ High accuracy

💍

Method 2 — Existing Ring (Diameter Method)

Step 1: Take a ring that fits the correct finger comfortably.
Step 2: Place it on a flat white piece of paper and trace the inside circle with a pencil.
Step 3: Measure the diameter of the traced circle straight across the centre in millimetres.
Step 4: Multiply the diameter by π (3.14159) to convert to circumference: e.g. 17.1mm × 3.14159 = 53.7mm.
Step 5: Find the nearest circumference in the master chart → read your target size in any system.
Alternatively: Find the diameter directly in the Diam.(mm) column of the chart below.

✅ High accuracy

🔢

Method 3 — Known Size in One System → Convert Using Chart

Step 1: Identify your known ring size and which system it belongs to.
Step 2: Find that size in the appropriate column of the master chart below.
Step 3: Read across the same row to find the equivalent in your target system.
Examples:
· UK N → find "N" in UK column → same row shows US 6.5 · EU 52 · 53.8mm
· US 9.5 → find "9.5" in US column → same row shows UK T · EU 61 · 61.4mm
· EU 55 → find "55" in EU column → same row shows UK P · US 7.5 · 56.3mm
This is the fastest method when you already have a known size in any system.

✅ Instant — no measuring

🧮

Method 4 — Free Online Calculator (This Page)

Step 1: Scroll to the calculator section below.
Step 2: Select your input type from the dropdown (UK/AU letter · US/CA number · EU number · mm circumference · mm diameter · cm circumference).
Step 3: Enter your known value in the input field.
Step 4: Click "Convert Ring Size Now" — the result instantly shows your equivalent in all 5 systems plus exact mm circumference and diameter.
The calculator automatically finds the nearest standard size in every system and displays all outputs simultaneously — no chart lookup needed.

⚡ Fastest method — all systems at once

🏪

Method 5 — In-Store Ring Sizer (Most Accurate)

Step 1: Visit any jeweller — Goldsmiths, Beaverbrooks, H.Samuel, Ernest Jones, Pandora, or an independent jeweller.
Step 2: Ask for a ring sizing — staff will use a set of mandrel gauges (metal rings in every size) to find your exact fit.
Step 3: They will provide your size in the local system (UK letter in British stores · US number in American stores · EU number in European stores).
Step 4: Use the master chart or calculator below to convert that confirmed size to any other system as needed.
This method is free at all major jewellers and provides the most reliable confirmed size.

⭐ Most accurate — professional measurement

📐

Bonus — The mm Formula for Any Conversion

All ring size systems ultimately rest on one physical measurement: the inner circumference in mm. Here are the key formulas:

Diameter → Circumference: C = D × π (× 3.14159)
Circumference → Diameter: D = C ÷ π (÷ 3.14159)
EU size → mm circumference: EU size ≈ circumference in mm
cm → mm: multiply by 10
inches → mm: multiply by 25.4

Once you have the circumference in mm — find it in the Circ.(mm) column of the master chart below and read any system's size in the same row.

🔢 Universal — works for all systems

⚡ Quick Conversion Pairs — Most Common Sizes 2026

🇬🇧 UK → 🇺🇸 US Conversion

UK LUS 5.5
UK MUS 6
UK N ⭐US 6.5 ⭐
UK OUS 7
UK PUS 7.5
UK QUS 8
UK RUS 8.5
UK SUS 9
UK T ⭐US 9.5 ⭐
UK UUS 10
UK VUS 10.5
UK WUS 11

🇺🇸 US → 🇬🇧 UK Conversion

US 5.5UK L
US 6UK M
US 6.5 ⭐UK N ⭐
US 7UK O
US 7.5UK P
US 8UK Q
US 8.5UK R
US 9UK S
US 9.5 ⭐UK T ⭐
US 10UK U
US 10.5UK V
US 11UK W

🇪🇺 EU → 🇬🇧 UK Conversion

EU 50UK L
EU 51UK M
EU 52 ⭐UK N ⭐
EU 54UK O
EU 55UK P
EU 57UK Q
EU 58UK R
EU 60UK S
EU 61 ⭐UK T ⭐
EU 63UK U
EU 64UK V
EU 65UK W

🇪🇺 EU → 🇺🇸 US Conversion

EU 50US 5.5
EU 51US 6
EU 52 ⭐US 6.5 ⭐
EU 54US 7
EU 55US 7.5
EU 57US 8
EU 58US 8.5
EU 60US 9
EU 61 ⭐US 9.5 ⭐
EU 63US 10
EU 64US 10.5
EU 65US 11

📊 Master Ring Size Conversion Chart – All Systems 2026

✅ How to Use This Chart to Convert Any Ring Size

Find your known ring size in the appropriate column (UK/AU letter · US/CA number · EU number · mm circumference · mm diameter). Then read across the same row to find the equivalent size in every other system. All five major sizing systems are shown side by side with exact mm values — making this the only chart you need for any ring size conversion in 2026.

🇬🇧 UK / 🇦🇺 AU	🇺🇸 US / 🇨🇦 CA	🇪🇺 EU	Circ. (mm)	Diam. (mm)	Circ. (cm)	Circ. (inches)	Best For
A	—	37	37.8 mm	11.9 mm	3.78 cm	1.488″	Children / XS
B	1	38	39.1 mm	12.3 mm	3.91 cm	1.539″	Children / XS
C	1.5	40	40.4 mm	12.7 mm	4.04 cm	1.590″	XS Women
D	2	41	41.7 mm	13.1 mm	4.17 cm	1.642″	Small Women
E	2.5	42	42.9 mm	13.5 mm	4.29 cm	1.689″	Small Women
F	3	43	44.2 mm	13.9 mm	4.42 cm	1.740″	Small Women
G	3.5	45	45.5 mm	14.3 mm	4.55 cm	1.791″	Women
H	4	46	46.8 mm	14.7 mm	4.68 cm	1.843″	Women
I	4.5	47	48.0 mm	15.1 mm	4.80 cm	1.890″	Women
J	4.75	48	48.7 mm	15.5 mm	4.87 cm	1.917″	Women
K	5	49	50.0 mm	15.9 mm	5.00 cm	1.969″	Women
L	5.5	50	51.2 mm	16.3 mm	5.12 cm	2.016″	Women
M	6	51	52.5 mm	16.7 mm	5.25 cm	2.067″	Women
N ⭐	6.5	52	53.8 mm	17.1 mm	5.38 cm	2.118″	Women's Avg ⭐
O ⭐	7	54	55.1 mm	17.5 mm	5.51 cm	2.169″	Women Popular
P ⭐	7.5	55	56.3 mm	17.9 mm	5.63 cm	2.217″	Women Popular
Q	8	57	57.6 mm	18.2 mm	5.76 cm	2.268″	Slim Men
R	8.5	58	58.9 mm	18.6 mm	5.89 cm	2.319″	Lean Men
S	9	60	60.2 mm	19.1 mm	6.02 cm	2.370″	Avg Slim Men
T ⭐	9.5	61	61.4 mm	19.56 mm	6.14 cm	2.417″	Men's Avg ⭐
U ⭐	10	63	62.7 mm	19.96 mm	6.27 cm	2.469″	Men Popular
V ⭐	10.5	64	64.0 mm	20.37 mm	6.40 cm	2.520″	Men Popular
W	11	65	65.3 mm	20.78 mm	6.53 cm	2.571″	Athletic Men
X	11.5	67	66.6 mm	21.18 mm	6.66 cm	2.622″	Broad Men
Y	12	68	67.8 mm	21.59 mm	6.78 cm	2.669″	Large Build
Z	12.5	69	68.5 mm	21.79 mm	6.85 cm	2.697″	XL Build
Z+1	13	70	69.7 mm	22.20 mm	6.97 cm	2.744″	XL Custom
Z+2	13.5	72	72.3 mm	23.01 mm	7.23 cm	2.846″	Custom

🇦🇺 AU = 🇬🇧 UK — no conversion

🇨🇦 CA = 🇺🇸 US — no conversion

🇬🇧 UK N = 🇺🇸 US 6.5 = 🇪🇺 EU 52 👩

🇬🇧 UK T = 🇺🇸 US 9.5 = 🇪🇺 EU 61 👨

⬆️ Between sizes — always go larger

🧮 Ring Size Conversion Calculator – All Systems 2026

Enter any ring size in any system → get all 5 system equivalents instantly

Ring Size — All 5 Systems

—

💡 UK / AU Letter Input — How to Enter

Since UK/AU sizes are letters, enter the letter's position in the alphabet as a number — for example: K=11 · L=12 · M=13 · N=14 · O=15 · P=16 · Q=17 · R=18 · S=19 · T=20 · U=21 · V=22 · W=23 · X=24 · Y=25 · Z=26 · Z+1=27 · Z+2=28. Alternatively, use any other input type (US/CA number, EU number, or mm measurement) — the UK letter will appear automatically in the result.

💡 Ring Size Conversion Tips & Rules 2026

1

AU = UK — Never Convert Between These Two Australian ring sizes use the identical A–Z+2 letter system as the UK. AU size N = UK size N — same circumference (53.8mm), same diameter (17.1mm), same fit. No conversion is ever needed between Australian and UK ring sizes. This also applies to New Zealand and South Africa.
2

CA = US — Never Convert Between These Two Canadian ring sizes use the same 1–13.5 numeric scale as the United States. CA size 6.5 = US size 6.5 — identical in every way. When converting an EU or UK size to Canadian, use the EU→US or UK→US chart — the result is your CA size directly. No extra step needed.
3

US Half-Size = One UK Letter — The Easy Rule Each 0.5 increment in the US system moves up by exactly one UK letter in the alphabet. US 6 = UK M → US 6.5 = UK N → US 7 = UK O → US 7.5 = UK P. Count up or down from a known anchor (e.g. US 6.5 = UK N) to estimate any nearby US to UK conversion quickly without the chart.
4

EU Size = Circumference in mm — The Logic Rule The EU size number directly equals the finger's inner circumference in millimetres. If you measure your finger with a string and the circumference is 55mm — your EU size is 55, which converts to UK P / US 7.5. This makes EU the easiest system to convert from a raw mm measurement.
5

Always Round Up — Choose the Larger Size When Between Two If your measurement or conversion result falls between two standard sizes — always select the larger size. A ring that is slightly large is comfortable to wear and easy to remove. A ring that is too small is uncomfortable and can restrict circulation. Most jewellers offer free resizing within 30 days as a safety net.
6

Measure in the Evening at Room Temperature Finger size fluctuates throughout the day. Fingers are smallest in the morning and after being cold. They are largest in the evening (5–9pm) and when warm. Always measure or confirm a ring size in the evening at room temperature for the most accurate everyday fit. Avoid measuring after exercise or in very hot or cold conditions.
7

Wide Bands — Go Up Half to One Full Size Wide rings (4mm+ width) compress against the natural taper of the finger and feel tighter than narrow rings at the same size. When converting a size for a wide wedding band — add ½ UK/US size for a 4–6mm band, or add 1 full UK/US size for a band wider than 6mm. Apply this upward adjustment after completing the system conversion.
8

Diameter Formula — Convert mm Diameter to Any System Multiply the inner diameter in mm by π (3.14159) to get the circumference. Then find the circumference in the chart: e.g. 17.1mm × 3.14159 = 53.7mm ≈ 53.8mm = UK N / US 6.5 / EU 52. Reverse: divide circumference by 3.14159 to get diameter. This formula works for any ring size in any country.

❓ How to Convert Ring Sizes – FAQ 2026

What is the easiest way to convert a ring size? ▾

The easiest method is to use the free calculator on this page — enter your known size in any system (US, EU, UK/AU, or mm) and it instantly shows the equivalent in all other systems at once. If you prefer a manual method, the master chart above works for any size: find your known size in the appropriate column and read across the same row for every other system's equivalent. For the most common conversions — UK N = US 6.5 = EU 52 (women's average) and UK T = US 9.5 = EU 61 (men's average) — these two anchor points let you estimate many nearby sizes without the chart.

How do I convert a ring size from US to UK? ▾

Use the easy rule: each US half-size = one UK letter going up the alphabet. US 6 = UK M → US 6.5 = UK N → US 7 = UK O → US 7.5 = UK P. From the men's anchor: US 9 = UK S → US 9.5 = UK T → US 10 = UK U → US 10.5 = UK V. Count up or down from these anchor points for any US size, or use the full chart above for sizes outside the common range.

How do I convert a ring size from EU to UK? ▾

Find your EU size in the EU column of the master chart above and read the UK letter in the same row. The most common conversions: EU 50=UK L · EU 51=UK M · EU 52=UK N · EU 54=UK O · EU 55=UK P · EU 57=UK Q · EU 58=UK R · EU 60=UK S · EU 61=UK T · EU 63=UK U · EU 64=UK V. If your EU size falls between two listed values (e.g. EU 53) — choose the larger UK letter (UK O in this case).

How do I convert a ring size from mm to UK, US or EU? ▾

If you have the circumference in mm — find the nearest value in the Circ.(mm) column of the master chart and read the UK, US or EU equivalent in the same row. If you have the diameter in mm — multiply by 3.14159 to get circumference first, then use the chart. Example: 17.1mm diameter × 3.14159 = 53.7mm ≈ 53.8mm = UK N / US 6.5 / EU 52. Alternatively, enter your mm value directly into the calculator above and it will find all system equivalents automatically.

Do I need to convert between Australian and UK ring sizes? ▾

No — Australian ring sizes are identical to UK ring sizes. Both countries use the same A–Z+2 alphabetical letter system with the same circumference and diameter values at every letter. AU size N = UK size N = 53.8mm circumference = 17.1mm diameter. No conversion is ever needed. New Zealand and South Africa also use the same system.

Do I need to convert between Canadian and US ring sizes? ▾

No — Canadian ring sizes are identical to US ring sizes. Both countries use the same 1–13.5 numeric scale. CA 6.5 = US 6.5 — identical circumference, identical fit. When converting EU or UK sizes to Canadian, use the EU→US or UK→US chart and the result is your CA size directly — no extra step required.

What if my ring size conversion falls between two sizes? ▾

Always choose the larger of the two sizes. A ring that is slightly large is far more comfortable to wear than one that is too tight. It can also be adjusted easily using an inexpensive silicone ring adjuster insert if needed. Most major jewellers in the UK, US, Australia and Canada offer free resizing within 28–30 days of purchase — use this as your backup when ordering online between sizes.

What is the most accurate way to convert a ring size? ▾

The most accurate conversion method is to start with a confirmed in-store measurement (Method 5 above) — a jeweller's mandrel gauge gives you a precise size in your local system, which you then convert using the chart. If in-store measurement is not possible, measuring the inner diameter of an existing well-fitting ring with a ruler (Method 2) and converting via the Diam.(mm) column is highly accurate. The string method (Method 1) is also reliable when done carefully in the evening. All three methods produce results accurate to within ±0.5 UK/US size.

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🎁 Special Situations

✅ Fit & Sizing

🌡️ Size Changes

🎁 Gifts & Proposals

How to Convert Ring Sizes – Complete 2026 Guide

How to Convert Ring Sizes — The Essentials

The Fastest Way to Convert Any Ring Size

Method 1 — String or Paper Strip (Measure Finger)

Method 2 — Existing Ring (Diameter Method)

Method 3 — Known Size in One System → Convert Using Chart

Method 4 — Free Online Calculator (This Page)

Method 5 — In-Store Ring Sizer (Most Accurate)

Bonus — The mm Formula for Any Conversion

🇬🇧 UK → 🇺🇸 US Conversion

🇺🇸 US → 🇬🇧 UK Conversion

🇪🇺 EU → 🇬🇧 UK Conversion

🇪🇺 EU → 🇺🇸 US Conversion

✅ How to Use This Chart to Convert Any Ring Size

Enter any ring size in any system → get all 5 system equivalents instantly

💡 UK / AU Letter Input — How to Enter

How to Convert Ring Sizes — The Essentials

The Fastest Way to Convert Any Ring Size

Method 1 — String or Paper Strip (Measure Finger)

Method 2 — Existing Ring (Diameter Method)

Method 3 — Known Size in One System → Convert Using Chart

Method 4 — Free Online Calculator (This Page)

Method 5 — In-Store Ring Sizer (Most Accurate)

Bonus — The mm Formula for Any Conversion

🇬🇧 UK → 🇺🇸 US Conversion

🇺🇸 US → 🇬🇧 UK Conversion

🇪🇺 EU → 🇬🇧 UK Conversion

🇪🇺 EU → 🇺🇸 US Conversion

✅ How to Use This Chart to Convert Any Ring Size

Enter any ring size in any system → get all 5 system equivalents instantly

💡 UK / AU Letter Input — How to Enter

🔗 Country-Specific Ring Size Conversion Guides