No paper. No guesswork. Place your ring on your iPhone screen and get your exact size in seconds — free, instant, and accurate.
5.84k+ downloads · 4.8 stars
Everything you need to find the perfect ring size — no jeweler visit required.
Accurate Measurement
Place your ring on screen and get precise measurements calibrated to your device.
Family Profiles
Save ring sizes for everyone — partner, family, friends. Always have sizes ready.
Global Size Standards
Supports US, UK, EU, Japan, Australia, and more international standards.
Finger Measurement
No ring? Measure your finger directly using the string method calculator.
Offline & Private
Works fully offline. Your data never leaves your device. Zero tracking.
Instant Results
Your size appears immediately in all major standards — US, UK, EU, and more.
Engagement Ready
Planning a surprise proposal? Secretly measure a ring while they're away.
Size History
Track how your ring size changes over time with measurement history.
Beautiful Design
Clean, intuitive interface designed for simplicity. No clutter, just results.
Use our free online tool. No download needed.
Step 1: Calibrate Your Screen
Place a standard credit card on your screen for pixel density calibration.
Place your ring on the screen and drag the handles to match its inner edge.
Your Ring Size
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US Size
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UK Size
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EU Size
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Japan Size
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Diameter (mm)
Tip: Calibrate your screen with a credit card first for maximum accuracy. Want size history, family profiles, and advanced features? Download the app.
A standard credit card is 85.6mm wide. Drag the handles to match your card's width exactly.
No jeweler visit. No guesswork. Just your phone.
Place Your Ring
Lay your ring flat on the iPhone screen — no paper or tools needed.
Align the Edges
Drag the on-screen guide to match the inner edge of your ring perfectly.
Get Your Size
Your exact ring size in every standard is shown instantly — US, UK, EU, and more.
Buy jewelry anywhere in the world with confidence.
US
& Canada
UK
& Australia
EU
Europe
JP
Japan
IN
India
mm
Diameter
Ring Sizer works entirely offline. Your measurements never leave your device. We don't collect, share, or sell any of your data. Ever.
"Used this app to measure ring size. It's accurate and it's really helpful."
Pradep12 · App Store Review
Our app uses precise screen calibration to match your ring to on-screen guides, ensuring highly accurate results comparable to professional jeweler tools.
No external tools or printouts are required. Simply use your iPhone screen to measure your ring or finger.
Ring Sizer supports multiple regional size systems including US/Canada, UK, Europe, Japan, India, Australia, and more.
Yes. All measurements are stored locally on your device and the app works completely offline. We never collect, share, or sell your data.
Yes! Ring Sizer is a free ring sizer app for iPhone that lets you measure your ring size on your phone screen in seconds. Just place your ring on the screen, align it with the guide, and get your size in US, UK, EU, and other standards. No tools or paper needed — download it free from the App Store.
Absolutely. With the Ring Sizer app, you place your existing ring directly on your iPhone screen and use the on-screen circle guide to match the inner diameter. The app uses screen calibration to ensure accurate results. You can also measure your finger using the string method calculator built into the app.
UK ring sizes use letters (A–Z) while US sizes use numbers (1–13+). For example, UK J = US 5, UK L = US 6, UK N = US 7, and UK P = US 8. For exact conversions, use our UK to US ring size converter or check the full ring size chart.
The average women's ring size in the US is 6 to 6.5 (UK L–M), while the average men's ring size is 10 to 10.5 (UK T–U). However, ring sizes vary significantly by individual — your best bet is to measure accurately using a ring sizer app rather than guessing based on averages.
Guides, tools, and charts to help you find the perfect fit.
Ring Size Chart
Complete conversion chart for US, UK, EU, Japan, and Australian ring sizes with diameter in mm.
How to Measure Ring Size at Home
5 free methods to find your ring size without visiting a jeweler — app, string, paper strip, and more.
Ring Size Calculator
Enter your ring diameter or circumference to instantly find your size in every international standard.
UK Ring Sizes (A–Z)
British letter-based sizing guide with full chart, Hatton Garden tips, and UK to US conversion.
Men's Ring Size Guide
Average men's ring sizes, measurement tips, and a complete chart for wedding bands and signet rings.
Secret Engagement Ring Sizing
How to find your partner's ring size without them knowing — clever tips for surprise proposals.
Free to download. Works on any iPhone. No tools needed.
No tools needed · Works offline · 100% private
