Ruler Kit - Protractor & Level

No tape measure nearby? Your phone screen is the ruler.

Ruler Kit packs an on-screen ruler, a protractor, a bubble level, a compass and a vibration meter into one small app. Lay an object on the screen, drag two cursor lines to its edges and read the length live, in cm or inches.

■ Accurate in one tap
Every phone screen is a little different, so calibrate once: hold any ID-1 card (bank card, transit card or ID card, 85.6 mm) against the screen, or line up 5 cm on a real ruler. After calibration the ruler shows an honest ± error so you know how far to trust each reading. Until then, a "calibrate" badge reminds you.

■ The tools
• Ruler — two draggable cursor lines, live reading, cm / inch toggle, fullscreen mode
• Protractor — drag two arms to read any angle
• Bubble level — roll and pitch in degrees plus slope in %, for shelves, frames and furniture
• Compass — points to magnetic north, with a figure-8 hint when it needs recalibrating
• Vibration meter — live graph in m/s² with current and peak values (an estimate, not a certified seismometer)

■ Keep what you measure
• Save measurements to history
• Home-screen widget shows your last measurement
• Built-in illustrated help guide
• Dark mode and 14 languages

■ Who it's for
DIYers hanging a picture, shoppers checking whether something fits, students who forgot their protractor, and anyone who needs a quick ruler or level without digging through a toolbox.

■ Private by design
No camera, no location, no account. Your measurements are stored on your phone and never leave it.

■ Honest about accuracy
Readings are approximate and based on your screen's physical size. Calibrating once gets you close, and the ± error tells you how close. For precision work, use a dedicated instrument.

Ads keep the app running; remove them anytime with a one-time purchase.

Open Ruler Kit and measure the next thing in front of you.

Recent changes:
First release. Ruler Kit brings an on-screen ruler (cm/inch), protractor, bubble level, compass and vibration meter together in one app. Calibrate in one tap with a bank or transit card, save readings to history and see your last measurement on a home-screen widget. Dark mode and 14 languages included.