Frequently asked questions

Open Free Online Protractor, drop or paste any image (PNG, JPG, PDF, SVG), then click three points: the vertex first, then one point along each ray. The angle appears instantly with an honest ± uncertainty figure. No sign-up, no install — it runs entirely in your browser.

Upload your photo, screenshot, or PDF to the canvas and place three clicks — vertex, then two ray endpoints. The tool calculates the angle from the pixel coordinates and shows it with its uncertainty. You can also use the Chain tool to measure several connected angles in one pass.

Load the image that contains the angle into our free protractor, click the three points that define it, and read the result. Each measurement includes a ± value so you know how much to trust the reading. See the step-by-step guide for details.

The maths is exact — accuracy depends on how precisely you place points, image resolution, and whether the camera was square to the surface. Our tool shows a per-measurement ± uncertainty so you always know the margin. Read more on the accuracy page.

Open freeprotractoronline.com in your phone's browser, snap or upload a photo, and tap three points. Touch targets are finger-sized, and pinch-to-zoom lets you place points precisely. No app install needed.

Take a photo of the angle, open this site on your phone, upload the image, then tap three points — vertex first, then one along each side. The angle and its uncertainty appear immediately. You can also paste a screenshot directly from your clipboard.

Yes. This free tool lets you measure as many angles as you like on any image — PNG, JPG, WebP, GIF, SVG, or PDF. Every measurement appears in a results table you can export as CSV, SVG, or a 4× PNG.

Photograph the angle, open this site, and click three points on the image. The tool computes the angle from pixel coordinates — no physical protractor required. For best results, shoot the photo straight-on so perspective does not skew the reading.

For measuring angles on photos and documents, a browser-based tool like Free Online Protractor works on every device without installation. It supports PDF and SVG files, shows per-measurement uncertainty, and exports results — features most native apps lack.

Yes — this site is a completely free protractor that works in any browser. There is no paywall, no sign-up, and no ads. All features including multi-angle measurement, calibrated rulers, grid overlays, and CSV/SVG/PNG export are included at no cost.

Google does not offer a built-in protractor tool. For a free alternative, use Free Online Protractor: upload an image and click three points to measure any angle — with honest ± uncertainty, export options, and full privacy (your files never leave your browser).

Yes. Open this website in your mobile browser, upload or take a photo, and tap three points to measure. The interface is optimised for touch with large handles and pinch-to-zoom — no app download required.

Absolutely. Upload any image to Free Online Protractor, click three points, and the angle is computed instantly. You can measure multiple angles, use the Chain tool for connected angles, and export everything as a CSV or report.

This one is — every feature is free with no account, no ads, and no usage limits. Multi-angle measurement, ruler calibration, grid overlays, and all export formats (CSV, SVG, 4× PNG, print/PDF) are included.

Yes. Take a photo of the angle and open it here. Click the vertex and two ray points, and the precise angle appears with its ± uncertainty. The tool replaces a physical protractor for most common tasks — just make sure the photo is taken straight-on for the best accuracy.

Load an image, then click three times: the corner first, then a point along each edge. The reading appears immediately. Full walkthrough on the how to use page.

No, and there is no way to make one. There is no sign-in link anywhere on this site.

PNG, JPG, WebP, GIF, SVG and PDF. You can also paste a screenshot with Ctrl/Cmd+V, or drop a file onto the page.

Yes — just start clicking on the empty canvas. Useful for demonstrating an angle rather than measuring one.

Yes. Handles have finger-sized touch targets and you can pinch to zoom. Reported uncertainty is higher on touch, because a fingertip cannot place a point as precisely as a cursor.

The angle is computed exactly from the coordinates you place. The uncertainty comes from where you click, how sharp the image is, and camera perspective — so each reading shows its own ± figure. See accuracy and limits.

Because it is real. Zooming in lets you place points more precisely in image terms, so the uncertainty genuinely falls. Drawing longer rays does the same.

A single figure would be meaningless without stating the image quality and ray lengths it assumed. Tools that advertise something like ±0.1° are quoting a number that cannot apply to your measurement.

Almost always perspective. If the camera was not square to the surface, the projection changes the angles, and no amount of careful clicking recovers them. Re-shoot square-on, centred, without a wide-angle lens.

No. Confirm anything consequential with a calibrated instrument. This is not a medical device and must not be used for diagnosis or treatment decisions.

Because that is roughly what a click on a raster image supports. You can raise it to four, but extra digits show more precision, not more accuracy.

No. Files are opened and measured in your browser. Open your developer tools Network tab while measuring and you will see no requests at all.

Your images and measurements are never uploaded. We use Google Analytics for anonymous page-visit statistics only — it does not receive your files. Fonts are served from this domain, not a CDN. See the Privacy Policy for details.

Your current workspace and any loaded image are saved locally in IndexedDB so an accidentally closed tab can be recovered, plus a single localStorage entry for your theme choice. Nothing leaves your device, and you can erase all of it from the tool.

No. Multiple measurements, snapping, the grid, scale calibration, CSV, SVG and 4× PNG export are all simply included. There is no pricing page.

Yes, as many as you like, and they appear together in the results table. The Chain tool measures every interior angle along a path in one pass.

Set a scale by clicking two points a known distance apart and entering that distance. Note it is a single-plane scale, accurate for features on the same plane as your reference.

Use Print / Save as PDF, which goes through your browser’s print dialog — so you choose the filename and page size, and it also prints on paper.

Yes. It is written with a UTF-8 byte-order mark and CRLF line endings, which is what Excel expects — degree signs and labels come through intact.

Export a JSON workspace and re-import it later. Your most recent work is also autosaved locally, and you will be offered it if you reopen the page.