Ruler: Measure, Level & Tools

Need to measure something right now and there's no ruler in sight? Your phone already has one.

Ruler Toolkit turns your phone into a pocket measuring kit: a card-calibrated on-screen ruler, a protractor, a bubble level, a compass, camera measure and a handful of sensor tools — all in one lightweight, sign-up-free app that gets straight to the point.

WHAT YOU GET On-screen ruler — measure in cm, mm or inches, with a 2-point mode and adjustable zero Real card calibration — fit a standard card (credit-card / ISO size) to the outline and correct your screen's true DPI, because every device is different Protractor — measure angles on screen with two arms, complement readout and automatic snapping to common angles Bubble level — surface mode (phone flat) and edge mode (long edge against the piece), with zero and hold Compass — find north with figure-8 calibration; keep the phone away from metal and magnets Camera measure — point at the floor or a wall and measure real-world distances in AR (needs an ARCore-certified device) Metal detector — spot ferrous metal by the change it makes in the magnetic field Light meter — read ambient light in lux, from dark to full sunlight Altimeter — set a zero point and read your relative height gain from barometric pressure Vibrometer — rest the phone on a surface and monitor its vibration Flashlight — instant screen light at a tap Saved measurements — keep lengths, angles and levels with a note ("shelf width"), filter, search and export 5 languages — English, Portuguese, Spanish, French and German

CALIBRATE ONCE, TRUST IT AFTER An uncalibrated screen ruler is just a guess: the real size of a centimeter changes from device to device. Card calibration takes seconds — drag the handle until the outline matches a real card, and from then on your on-screen measurements reflect your actual screen.

MADE FOR EVERYDAY JOBS Assembling furniture, hanging a picture, checking an angle, leveling a shelf, finding north at the campsite: the small measurements of daily life, solved without digging out the toolbox.

AN HONEST NOTE ON SENSORS Some tools rely on hardware your phone may or may not have. The compass and metal detector need a magnetometer, the level and vibrometer use the accelerometer, the altimeter needs a barometer, the light meter needs an ambient-light sensor, and camera measure needs an ARCore-certified device. If a sensor is missing, that tool simply stays out of your way — the ruler, protractor and flashlight work on virtually any phone.

SIMPLE AND PRIVATE No sign-up and no account required. Your saved measurements and calibration stay on your device; optional Google backup is there only if you want to restore on a new phone. Erase everything anytime in Settings.

Keep a whole toolbox in your pocket — download Ruler Toolkit.