About Us
Ruler Size started with a simple frustration: every online ruler we tried was either inaccurate, cluttered with ads, or required a sign-up just to see a scale. So we built one from scratch — free, fast, and calibrated to your actual screen.
Our goal is to give anyone — students, designers, makers, engineers, and everyday people — a precision measurement tool that opens in one click and works on every device they own.
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Auto-calibration recognises 200+ devices so your first measurement is correct immediately — no setup screens, no sliders.
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We store only your calibration preference in your own browser. No accounts, no analytics, no tracking of any kind.
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Every feature — ruler, protractor, set square, crosshair, dark mode, multilingual UI — is free with no paywall and no subscription.
Ruler Size ships a pixel-perfect ruler that snaps to any screen edge and measures in inches, centimetres, and millimetres at true actual size. On top of that we added a full-rotation protractor, a 30-60-90 set square overlay, and a live crosshair that reads X/Y coordinates in real time — tools that used to require desktop software or physical instruments.
Calibration works three ways: auto-detect by device fingerprint (covers most phones, tablets, and monitors), screen diagonal input, or a physical credit card reference. All three persist in your browser so you only calibrate once per device.
The UI is translated into 18 languages, responds fully to touch gestures, and supports a dark theme that makes low-light measurement comfortable. No backend, no server, no data collection — just a fast, reliable measurement tool that loads in under a second.