Ring Size Converter
Convert ring sizes between US, UK, EU, French, Swiss, and Japanese standards. Free online ring size converter for jewelry shopping, gifting, and custom ring orders worldwide.
Ring Size Measurement Systems
Ring sizes vary by country and measurement method. US uses a numbered scale based on circumference. UK uses letters A-Z. EU uses circumference in millimeters. Understanding these systems ensures proper ring fit when shopping internationally.
Ring Size Formulas
Circumference (mm) = Diameter (mm) × π
US Size = (Circumference - 36.5) / 3.15
EU Size = Circumference in mm
UK Size = (Circumference - 36.25) / 1.25 (letter)
Circumference is the distance around the finger. Diameter is the distance across the ring. Pi (π) equals approximately 3.14159. Measure at end of day when fingers are warmest.
International Ring Size Conversion Table
| US | UK | EU | France | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 44 | 14.1 | 44.2 |
| 4 | H | 47 | 47 | 14.9 | 46.8 |
| 5 | J | 49 | 49 | 15.7 | 49.3 |
| 6 | L | 51 | 51 | 16.5 | 51.9 |
| 7 | N | 54 | 54 | 17.3 | 54.4 |
| 8 | P | 57 | 57 | 18.1 | 57.0 |
| 9 | R | 59 | 59 | 18.9 | 59.5 |
| 10 | T | 62 | 62 | 19.8 | 62.1 |
| 11 | V | 64 | 64 | 20.6 | 64.6 |
| 12 | X | 67 | 67 | 21.4 | 67.2 |
How to Measure Ring Size
Ring Sizer Tool
Use plastic or metal ring sizer set
Slide rings onto finger
Find comfortable fit
Most accurate method
Measure Existing Ring
Measure inside diameter of well-fitting ring
Use ruler or caliper
Compare to size chart
Measure multiple rings for accuracy
String or Paper Method
Wrap string around finger base
Mark where string overlaps
Measure length in mm
This is circumference
Best Measurement Practices
Measure at end of day
Fingers swell in heat
Measure 3-4 times
Consider knuckle size
Ring Size Conversion Examples
Example 1: US to EU
US Size: 7
UK Size: N
EU Size: 54
Circumference: 54.4 mm
Example 2: EU to US
EU Size: 57
US Size: 8
UK Size: P
Diameter: 18.1 mm
Example 3: Circumference to Size
Circumference: 52 mm
US Size: 6
EU Size: 52
UK Size: L
Example 4: Diameter to Size
Diameter: 19 mm
Circumference: 19 × 3.14 = 59.7 mm
US Size: 9
EU Size: 60
Ring Sizing Tips
Finger Variations
Dominant hand: Slightly larger
Morning: Fingers smallest
Evening: Fingers largest
Temperature affects size
Ring Width Effect
Wide bands feel tighter
Add 0.25-0.5 for wide rings
Thin bands fit looser
Consider ring style
Knuckle Considerations
Ring must pass over knuckle
Size for knuckle if large
Add sizing beads for fit
Consider adjustable settings
Seasonal Changes
Summer: Fingers swell
Winter: Fingers shrink
Average for year-round wear
Resizing may be needed
Frequently Asked Questions
What is the average ring size for women?
Average women's ring size is US 6-7 (EU 51-54). Size 6 is most common for engagement rings. Sizes vary by country and individual. Always measure for accurate sizing.
What is the average ring size for men?
Average men's ring size is US 9-10 (EU 59-62). Size 10 is most common for wedding bands. Men's fingers vary more than women's. Measure before purchasing.
Can rings be resized?
Most rings can be resized 1-2 sizes up or down. Platinum and gold resize easily. Titanium and tungsten cannot be resized. Eternity bands are difficult to resize.
How do I know if a ring fits properly?
Ring should slide over knuckle with slight resistance. Should fit snugly but not tight. Should not spin freely. Should leave slight indentation when removed.
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