Penggaris Online

We’ve all been in the spot where you need to measure something small, like a coin, a screw, or a photo, and there’s no ruler nearby. Your phone is always within reach, though.

Penggaris Online turns that screen into a real ruler. The catch with most online rulers is that screens vary a lot, so “1 cm” on screen is usually just a guess. Penggaris Online fixes this by letting you calibrate with something you already own: hold an ATM card, ID, or driver’s license (85.60 mm wide) against the screen, slide until the edges match, and you’re done in about five seconds. After that, 1 cm on screen is 1 cm in real life.

It works in cm, mm, inches, and pixels, with rulers on any or all four screen edges, guide lines, and a crosshair. It’s free, needs no app, and does everything locally in your browser. It’s available in 34 languages, and it’s built for students, designers, tailors, DIYers, and anyone who just needs a quick measurement.