About Digital Protractor

Digital Protractor is a free, browser-based tool for measuring angles on real photos, diagrams, and blueprints — built because the existing options were either desktop-only, paywalled, or simply didn't work properly on a phone.

Why we built it

Most "online protractor" tools are a leftover print-and-measure worksheet, or a desktop app with touch support bolted on as an afterthought. Dragging a ray with a finger on a phone screen usually means your own hand blocks the exact point you're trying to place — which defeats the purpose of a precision tool. Digital Protractor was built mobile-first from day one: real pointer-capture, gesture handling that tells a drag apart from a pinch-zoom, and a magnified loupe that shows the point under your finger instead of hiding it.

What we believe

A measurement tool shouldn't need an account, a subscription, or a trip to a server. Every feature in Digital Protractor — multiple protractors, snapping, undo/redo, PNG and CSV export — is available the moment the page loads, for everyone, for free. Photos and diagrams you drop onto the canvas are decoded and measured directly in your browser and are never uploaded anywhere; closing the tab clears everything, because there's no account or server storage involved. Read the full details on our privacy policy.

The tool today, and what's next

Digital Protractor is actively maintained as a single, focused tool rather than a bundle of unrelated utilities. An on-screen ruler mode and a device-sensor spirit level are next on the roadmap — see the FAQ for the current state of both. If you run into a bug or have a feature you'd like to see, the contact page is the fastest way to reach us.