Unit Conversions

Ring Size Calculator | Find Your Ring Size from Finger Measurements

Find your exact ring size from finger circumference or diameter in millimeters or inches. Converts between US/Canada, UK/Australia/South Africa, EU/ISO, and Asian sizing systems. Includes a printable paper ring sizer template and resizing guidance by metal type.

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Measurement Method

Finger Circumference

Finger

Hand

Traditional engagement ring hand

How to Measure at Home

String method

Wrap a thin strip of paper or thread around your finger. Mark where it overlaps, then measure the length — that is your circumference.

Best practices

Measure in the afternoon (fingers swell in heat), avoid cold/morning measuring. Your knuckle should also fit through the ring.

Ring Sizing Systems Around the World

Different countries use completely different ring size systems. The US and Canada use numbers (typically 3–13.5); the UK and Australia use letters; Continental Europe (EU) and France/Russia use the inner circumference in millimeters; Japan uses sequential numbers starting from 1. When ordering rings internationally, always confirm the sizing standard used.

Tips for Accurate Ring Sizing

Time of day	Measure in the afternoon — fingers are largest then
Temperature	Fingers swell in heat and shrink in cold — measure at room temperature
Dominant hand	Slightly larger (usually 0.5 size) than non-dominant
Knuckle clearance	Ring must slide over the knuckle — size for the wider knuckle if needed
Width factor	Wider bands fit tighter — go up 0.5 size for bands wider than 6mm
When to avoid	Do not measure after exercise, alcohol consumption, or in hot weather

Getting Rings Resized

Most rings can be resized up to 2 sizes up or down by a professional jeweler. Eternity bands and rings with stones all around cannot be resized. Rings can typically be resized within 30–60 days of purchase at no cost from reputable jewelers.

For surprise purchases: If buying a ring as a surprise gift, most jewelers recommend ordering a size 7 for women (average US women's ring size) or asking a trusted friend/family member. Many jewelers offer free or low-cost resizing within 60 days of purchase.

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