Frequently Asked Questions

An online AR Ruler is a web-based augmented reality tool that uses your smartphone camera and ARCore depth sensing to measure real-world distances, areas, and volumes — all without installing any app. onlinearruler.pages.dev runs entirely inside your Chrome browser on Android, using the WebXR API to detect flat surfaces and anchor measurement points to the real world.

No. Online AR Ruler is a browser-based web-app — you open it in Chrome on Android and start measuring immediately. No Play Store download is needed. If your device does not have ARCore installed, the app will prompt you to install Google Play Services for AR (a free, one-time, 100 MB install that powers all AR apps on Android).

On ARCore-enabled devices, the app uses WebXR hit-test to detect flat surfaces in the camera view. When you tap to place a measurement point, the AR engine anchors it to a real-world 3D coordinate. The distance between two points is then the Euclidean distance between their 3D world-space positions — giving you a true real-world measurement. On non-ARCore devices, it uses reference calibration: you tap the two ends of a known object (such as a credit card at 85.6 mm) to establish a pixel-per-millimetre scale, and all subsequent measurements use that scale.

Full AR mode is supported on Android devices running Chrome (version 81+) with ARCore support. Most Android phones released after 2019 support ARCore. iOS (Safari and Chrome) does not currently support the WebXR hit-test API required for true AR measurement. Desktop browsers do not support immersive AR. The reference calibration fallback mode works on any device with a camera — including iPhones and desktop browsers.

Camera access is required to show the AR view and detect real-world surfaces. The camera feed is processed entirely on your device in real time — no images, video, or measurement data are ever transmitted to any server. Granting camera permission only enables the measurement tool and nothing else.

For full AR mode, your Android device needs to support Google ARCore. ARCore requires a device with a rear camera, Android 7.0 or later, and a compatible chipset. A full list of supported devices is available on the Google ARCore supported devices page. Phones such as the Samsung Galaxy S series, Google Pixel, OnePlus, Xiaomi Mi series, and most flagship and mid-range Android phones from 2019 onwards are supported. Older or low-end budget phones may not support ARCore but can use the calibration fallback mode.

Open the app and tap "Start AR Measurement". Point your phone camera at a flat surface — the floor, a table, or a wall. A glowing ring (reticle) appears when the AR system detects the surface. Tap the "+" button to place Point 1. Move your phone to the second location and tap "+" again for Point 2. The distance is displayed instantly. In Length mode, you can keep adding points to measure multi-segment paths. In Area mode, tap three or more corner points to measure a polygon area. In Volume mode, four guided taps measure length, width, and height.

On flat, textured surfaces in good lighting with a supported ARCore device, accuracy is typically within 1–3 cm for distances up to 3 metres. For larger distances (3–10 metres), expect 2–5 cm variance. Accuracy is better on surfaces with visible texture (wood, carpet, tiles) and worse on smooth, reflective, or uniformly coloured surfaces such as glass or white walls. The reference calibration fallback achieves approximately 5–10% accuracy when the calibration object is flat on the same plane as the measured surface.

Several factors influence measurement accuracy: (1) Surface texture — ARCore detects geometry better on textured surfaces. (2) Lighting — bright, even lighting improves depth detection. Avoid measuring in very dim conditions. (3) Distance — measurements are more accurate within 1–3 metres of the camera. (4) Camera stability — keep the phone steady when placing measurement points. (5) Surface type — flat horizontal surfaces (floors) give the best results. Vertical or angled surfaces may have higher variance.

Yes. The unit selector in the top bar lets you switch between centimetres (cm), millimetres (mm), inches (in), and feet (ft) at any time — including mid-measurement. All displayed values and labels update instantly when you change units.

No. Your camera feed is never recorded, stored, uploaded, or processed on any server. The entire AR measurement computation runs locally on your device inside the browser. We do not collect, transmit, or store any camera data, measurements, or personal information during your session. See our Privacy Policy for full details.

Currently, measurements are displayed on screen and can be noted or screenshotted using your device's built-in screenshot function. A dedicated "Save measurement" feature with export options is planned for a future update. In the meantime, your device screenshot (typically Power + Volume Down on Android) captures the full AR view with the measurement displayed.

Yes. Open Online AR Ruler in Chrome on Android, tap "Start AR Measurement", and point your camera at the floor. The app uses ARCore plane detection to find the floor surface. Tap to place measurement points at each wall corner and it calculates the real-world distance instantly. For a rectangular room, measure length and width in two passes — you have all the dimensions you need without any tape measure.

Full AR mode requires Android Chrome with ARCore — Apple's Safari and Chrome on iOS do not support the WebXR hit-test API required for real-world AR measurement. However, the reference calibration fallback mode works on iPhone: place a known object (like a credit card at 85.6mm) in frame, tap its edges to calibrate, and measure any surface on the same plane. This gives reasonable accuracy for quick measurements on iOS.

A regular online ruler (like onlineruler.io or ruler.im) measures objects placed directly against your phone or computer screen — it is a flat, 2D screen measurement tool. Online AR Ruler is completely different: it uses augmented reality to measure real objects in 3D space through your camera. You can measure the length of a sofa from across the room, the area of a floor, or the volume of a box — without touching the objects or placing anything on a screen.