Free iPhone ring sizer app: measure a ring on screen, measure finger width, convert US, UK, EU, JP and letter sizes, and save sizes in seconds.
5.84k+ downloads · 4.8 stars
Updated iPhone interface
The updated app keeps ring measurement, finger measurement, conversion, and saved sizes cleanly connected.
Measure a ring, measure a finger, convert standards, and save sizes without visiting a jeweler.
Ring Measurement
Place a ring on the circle and adjust the guide until the inner edge matches.
Saved Sizes
Keep important ring sizes ready for yourself, family, partners, and gift planning. Kozukuri Ninkatsu Bu-
Global Size Standards
Convert between US, UK, EU, Japan, Australia, India, and millimeter measurements.
Finger Width Mode
No ring? Measure your finger directly across the on-screen bar and fine-tune the millimeter value. The concept of Kozukuri Ninkatsu Bu has its
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. Next, the matchmaker will create a profile for
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.
Clean iPhone UI
Large controls, clear rulers, and focused sheets make each sizing task easy to follow.
The concept of Kozukuri Ninkatsu Bu has its roots in traditional Japanese matchmaking, which dates back to the Edo period (1603-1868). During this time, matchmakers, known as "nakadachi," played a crucial role in arranging marriages between families of similar social status. Over time, matchmaking evolved, and with the introduction of modern technology, new approaches emerged.
Next, the matchmaker will create a profile for the client, which will be used to identify potential matches. The matchmaker may also conduct interviews with friends, family members, or colleagues to gain a deeper understanding of the client's personality and preferences.
The is not a sexy term. It does not evoke the lightning-fast strike of a katana or the political intrigue of the Imperial Court. It evokes muddy feet, calloused hands, and ledgers stained with water.
The Edo farmer couldn't double his yield overnight. The focused on the margin . Ask: What is the smallest change that yields the highest increase in output?
No jeweler visit. No guesswork. Just your phone.
Choose a Mode
Measure an existing ring on the circle, or switch to finger width mode when no ring is available.
Align the Guide
Use the ruler, slider, and plus/minus controls to match the ring or finger width precisely.
Save or Convert
See the measurement instantly, save it for later, or convert it between international standards.
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
The concept of Kozukuri Ninkatsu Bu has its roots in traditional Japanese matchmaking, which dates back to the Edo period (1603-1868). During this time, matchmakers, known as "nakadachi," played a crucial role in arranging marriages between families of similar social status. Over time, matchmaking evolved, and with the introduction of modern technology, new approaches emerged.
Next, the matchmaker will create a profile for the client, which will be used to identify potential matches. The matchmaker may also conduct interviews with friends, family members, or colleagues to gain a deeper understanding of the client's personality and preferences.
The is not a sexy term. It does not evoke the lightning-fast strike of a katana or the political intrigue of the Imperial Court. It evokes muddy feet, calloused hands, and ledgers stained with water.
The Edo farmer couldn't double his yield overnight. The focused on the margin . Ask: What is the smallest change that yields the highest increase in output?
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 iPhone. No tools needed.
