Printable Protractor

Half circle or full

The 180 degree protractor is the classroom one: a half-circle with a flat base, numbered from zero to 180 in both directions so an angle can be read from whichever arm sits on the baseline. The 360 degree version is a full circle with a single scale running clockwise, used for bearings, compass work and anything measured from a fixed reference. Both have a small crosshair at the centre for the vertex and a tick at every single degree.

Reading it

Put the centre crosshair on the vertex of the angle and the baseline along one arm. Read where the other arm crosses the scale, using the row of numbers that starts at zero on the baseline arm. Beginners read the wrong row; the second row of smaller numbers on the 180 version is there so that whichever way the angle opens, one row starts at zero.

The base scale

The half-circle version can carry a centimetre scale along its base, measured out from the centre in both directions, so the same tool marks a length and an angle. It is the layout of the plastic protractors sold in school sets.

Size

Eight, ten, twelve or fifteen centimetres across. Ten is the standard school size. Fifteen is easier to read and better for wall charts or for a child who is still learning where to look. All of them print with a degree tick every single degree; on the eight centimetre version those ticks are about half a millimetre apart, which is as fine as paper takes.

Make it see-through

A paper protractor hides the angle under itself. Print on tracing paper or transparency film, or cut out the inner half-circle along its line so the vertex and the arms show through the hole. The sheet says so at the top.

Print at true size

The angles are right at any scale; a protractor scaled by ten percent still reads 45 degrees as 45. The centimetre base scale is not, and neither is the diameter you chose. The 10 cm check line at the top of the page tells you whether the printer scaled the sheet. Choose Actual size or 100 percent, never Fit to page.