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Calibrate
Ring Sizer knows the exact pixel geometry of every iPhone and iPad, then fine-tunes against a reference for true 1:1 scale.
Your exact ring size, measured in light.
Ring Sizer turns the screen in your hand into a jeweler-grade sizing instrument. Place a ring — or a finger — and read the exact size across every world standard. No calipers. No mail-order sizers. No guesswork.
US
UK / AU
EU
JP
MM
The App
An instrument, not just an app.
Every screen is engineered to feel like precious metal — dark, quiet, and exact. Below is the current build.
Coming soon. It's in beta.
HomeMeasure · Convert · Register
Measure a RingInner diameter to the 1/100 mm
Measure a FingerAt the knuckle, no ring needed
How It Works
Three quiet steps to an exact size.
No accessories, no mail-order kits. The whole flow takes under a minute.
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Place
Lay a ring flat over the circle, or rest a knuckle inside the gold ring. Nudge until the light lines up perfectly.
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Read & Save
Read the size in US, UK/AU, EU, JP and millimetres at once — then save it to a private register for later.
Why It's Different
Built to the tolerance of fine jewelry.
Sub-millimetre precision
Readings to the 1/100th of a millimetre — finer than most physical sizing gauges on a jeweler's bench.
Every world standard
US, UK & AU, EU, JP and raw millimetres, converted live as you adjust. One measurement, every market.
Private by design
No account, no tracking, no ads. Every saved size lives only on the device — nothing touches a server.
Two ways to measure
Size a finger at the knuckle when there's no ring to hand, or measure an existing ring's inner diameter.
Instant conversion
Bought abroad? Convert any size to any standard in a tap — no charts, no mental arithmetic.
A saved register
Keep every size for family and clients in one private register — ready the next time you're at the counter.
On the roadmap
The AI Vision
An AI that designs the perfect fit.
Sizing is only the beginning. We're building an AI layer that goes from a number to a finished piece — understanding how a band should sit on your finger, not an average one.
- Per-finger fit modelling — knuckle, taper and swelling accounted for, so a ring is comfortable all day.
- Generative ring design — describe a style and see rendered concepts sized precisely to the wearer.
- Jeweler hand-off — export exact specs and CAD-ready dimensions straight to the workshop.
- Confidence scoring — the app tells you how sure it is, and when a bench check is worth it.
For The Jewelry Trade
Bring exact sizing to your counter.
Give every client a precise, on-brand sizing experience — in-store or at home before they ever visit. We're partnering with select jewelers, ateliers and brands on white-label and pilot programs. If you're at a show and want to talk, so are we.