About PrintProtractor
PrintProtractor makes one thing and makes it correctly: a printable protractor that prints to its true size.
Search for a printable protractor and you will find plenty of images and PDFs. The problem is that most of them print at the wrong size, because the printer quietly scales the page to clear its margin, and the result is a protractor whose angles and ruler are off by a few percent. A few percent is enough to make a measurement useless.
We fixed that by building the geometry in real physical units and adding a calibration bar you can measure after printing. The protractor is drawn in millimetres and PDF points, never in screen pixels, so the size on paper matches the size you asked for. The 100 millimetre calibration bar lets you confirm it in two seconds.
How it works
When you set the size and marks, the tool draws the protractor on your own device and hands you a PDF or SVG. Nothing is uploaded. Each degree is placed with exact trigonometry, the baseline sits on the diameter with the origin at its centre, and the numbers run in both directions so you can read an angle from either side.
The on-screen preview is built from the same geometry as the file, so the preview is an honest picture of what will print. The only variable left is your printer, which is why the calibration bar is there.
How we check the tool
Before a change to the generator ships, an automated check opens the built site in a headless browser, generates the PDFs, and measures the files themselves. The page must be the chosen paper size to the PDF point, the calibration bar must be exactly 100 millimetres in the file's own coordinates, and the degree marks must land at their exact angles. A change that fails a check does not go live.
Those measurements rest on published constants, not on our say-so: a PDF point is 1/72 of an inch (ISO 32000), so a millimetre is 2.8346 points, US Letter is 612 by 792 points, and A4 is 595.28 by 841.89. The checks assert the same figures the drawing code uses, so the tool is tested against the standard rather than against itself.
Our accuracy standards
Every protractor that leaves this site follows the same rules:
- Drawn in physical units, millimetres and PDF points, never in screen pixels, so the file carries its true size.
- Every degree mark is placed by trigonometry from the centre, not traced or scanned from another image.
- A 100 mm calibration bar ships on the sheet, so you can verify the print instead of trusting it.
- The size is capped to the printable area of Letter or A4, so the arc never clips at a margin.
Who it's for
- Students and teachers who need a protractor for geometry homework, or thirty of them for a class, by tomorrow.
- Woodworkers and DIYers marking mitre cuts, roof slopes, and brackets.
- Sewists and quilters cutting wedges and fan blocks at repeatable angles.
- Anyone whose protractor went missing the evening it was needed.
Free and private
The tool is free, needs no account, and runs entirely in your browser. We do not see your settings or your files. If you have a question or spot something that looks off, the contact page reaches us directly.