Donaldson R F Printable Protractor & Ruler
Need to measure an angle or a length and have no tools to hand? Print one at true size in seconds.
Important: in the print dialog choose scale 100% (or “Actual size”), not “Fit to page”. Then check the 100 mm line at the bottom with a real ruler. The preview below is not to scale on your screen.
Getting an accurate print
A printed protractor or ruler is only as accurate as your printer settings. Print at 100% / Actual size, on plain paper, and use the 100 mm check line at the bottom of the page: if it measures 100 mm against a real ruler, everything else is correct too. For a protractor that lasts, print on thin card or stick the paper to card before cutting along the curved edge; the small cross marks the centre point, which you line up with the corner of the angle. The outer numbers count from the right (0° on the right, 180° on the left) and the inner numbers count from the left, so you can read an angle from whichever side its first line starts.
The ruler is drawn with millimetre marks, numbered centimetres and, if you choose, inch marks down to 1/16 in. Its maximum length depends on the paper: about 27 cm on A4 and 25 cm on US Letter (a little less than the full sheet width, to leave a margin). This is a convenient stand-in for occasional use, not a calibrated measuring instrument, so do not rely on it for anything where precision or certification matters.