AR Ruler turns an iPhone into a measuring kit. Six tools measure through the camera — distance, perimeter, height, area, volume and angle — and five more work without the camera at all: a real-size on-screen ruler, a bubble level, a protractor, a compass, and an offline unit converter.
My measurement looks wrong. What happened?
Camera measurement depends on the phone understanding the space around it, and four things break that: poor light, a surface with no visible texture (a plain white wall, glass, a mirror), moving the phone too quickly, and distance — accuracy falls off past about 3 metres. AR Ruler shows a confidence indicator on every measurement and names the specific problem when one of these applies. If it says the light is low or the surface has no texture, the number really is unreliable — move closer, add light, or aim at something patterned, then measure again.
How do I get the most accurate result?
Before the first measurement, move the phone slowly around the area for a few seconds so it can map the surfaces. Measure at arm's length rather than across the room. Keep the phone steady when you tap. Watch for the green confidence indicator.
Do I need an iPhone with LiDAR?
No. AR Ruler works on any iPhone that supports ARKit. On models that do have LiDAR (Pro models from iPhone 12 onward), the app uses that depth data automatically for better precision — you don't have to turn anything on.
Some tools work but the camera ones don't.
The camera tools need ARKit and camera permission. The screen ruler, level, protractor, compass and converter don't — they'll keep working regardless. If you declined camera access, you can grant it in Settings › AR Ruler.
Why does the on-screen ruler need calibrating?
To draw centimetres at their true size, the app needs to know your screen's exact pixel density. It knows most iPhone models already, but not ones released after this version. Calibration fixes that in seconds: lay any bank or credit card on the screen and resize the outline until it matches. Payment cards are manufactured to an exact international size (85.60 × 53.98 mm), which makes them a precise ruler.
Why does the compass ask for my location?
Because iOS only provides compass heading to apps with location permission — there is no way to show true north without it. The request appears only when you open the Compass tool, never at launch, and nothing about your location is stored or sent anywhere. The other ten tools never ask.
My bubble level says I'm off when the surface looks flat.
Phones aren't perfectly flat, and a case makes it worse. Put the phone on a surface you trust and tap Calibrate — the app stores that offset and subtracts it from then on. Reset Calibration undoes it.
Does it work offline?
Entirely. Every tool, including the unit converter, runs on the device. The app has no server.
How do I cancel my subscription?
Subscriptions are billed by Apple, not by us, so they're cancelled in your own account: open Settings, tap your name, then Subscriptions, and select AR Ruler. Cancelling at least 24 hours before the renewal date stops the next charge. See the terms.
I paid but the app still asks me to subscribe.
Tap Restore Purchases on the subscription screen. That re-checks your purchase with Apple and is the fix for a new device, a reinstall, or a restore from backup. Make sure you're signed in with the same Apple Account you bought with.
Can I trust it for construction or anything safety-critical?
No. Results are estimates from camera and sensor data. For anything where being wrong is expensive or dangerous, use a physical measuring tool.
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