Ring Sizer, frequently asked questions

Within about half a size, once you've calibrated properly. That's close enough for most online orders. What the app can't do is check whether your calibration is actually right, or whether your eye matched the circle well — both are on you. Save the jeweler visit for a surprise engagement ring or anything irreplaceable.

Yes, once per device, and it's a one-minute job: open Calibration, lay a real ruler against the screen, drag the Factor slider until the marks line up. The app recognises a long list of screen densities and guesses at the rest, and even recognised screens vary a little — calibration is the step that turns a drawn millimetre into a real one.

Open Finger Sizer and widen the two bars against your finger until they just touch. Same live readout as the ring tool, same calibration behind it.

The System Converter handles US, UK/AU, EU (Swiss), JP (Asian), circumference and diameter in any direction and shows every equivalent at once. For a quick lookup instead, the Size Chart is a plain 61-row table.

No account, full stop. Measuring, converting, the chart, the guides and your saved history all run offline. Only the ads and the Premium purchase screen need a connection — turn off Wi-Fi and you just get a quieter app.

Measure in the evening, at a normal room temperature. The Finger Guide puts the morning-to-evening swing at a quarter to half a US size, with cold shrinking fingers and heat or salty food swelling them. A ring needs to clear the knuckle on your biggest day, not your smallest.

No camera code, no AR, no photo access anywhere in the build. You're matching a drawn shape to a real object by eye; the calibrated screen does the millimetre math.

Inside edge, always. That's what a ring size actually measures. Line up the outer edge instead and you'll overshoot by a size or more.

US and Swiss/EU sizes get two decimal places, Asian sizes get one — it's just how the reference table is formatted. An 18.5 mm diameter rounds to US 8.50 in that table.

One, kept and visible at all times. Want a second slot that day? Watch a short ad (twice a day, max), or skip the ad loop entirely with Premium.

No, and the app says so on the result screen: This is an estimate only. It's built from gender, body frame, height range and finger, which is a demographic average, not your finger. Treat it as a starting guess, then measure for real.

Premium's History exports everything as CSV and can share a formatted report through the iOS share sheet. On the free tier you can still share a short text summary.

A Premium table of all 61 sizes — diameter, US, UK, EU, JP, circumference, side by side — with search, a system filter and row copying. Overkill if you only need your own size once.

Only for ad targeting on the free tier. Decline and you keep seeing ads, just not aimed at you. Premium drops the ads, and the question, entirely.

iPhone and iPad only, no widgets. If you need Android, this isn't it.

Adds a fixed offset: +0.25 comfort, +0.5 wide band, +1.0 extra wide, -0.25 snug. It's optional — leave it on Standard (no adjustment) unless a specific band style calls for it.

On the device, in the app's own storage, nowhere else. Delete the app and the history goes with it — there's no backup to fall back on.