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A free paper protractor you can print at real size: a 180° half-circle and a 360° full circle, each 10 cm across with 1° tick marks and numbers every 10°. Print at 100%, check the built-in 10 cm ruler, cut it out. Download the SVG or print straight from this page — only the protractor goes to the printer.
Half-circle, 10 cm diameter. 1° ticks, numbers every 10° on an outer and an inner scale, centre crosshair, and a 10 cm ruler along the base so you can confirm the print is true size.
Print at 100% / actual size — uncheck "Fit to page". Then check that the ruler reads 10 cm.
Full circle, 10 cm diameter. 1° ticks, a single scale numbered every 10° with 0° on the right, centre crosshair with both axes, and a 10 cm check ruler. Reads reflex angles (over 180°) directly.
Print at 100% / actual size — uncheck "Fit to page". Then check that the ruler reads 10 cm.
Pick the 180° half-circle for schoolwork and most drawing, or the 360° full circle for reflex angles and bearings. Press Print, or download the SVG and print it from any image viewer.
In the print dialog set Scale to 100% or "Actual size". Turn off "Fit to page", "Shrink to fit" and "Scale to fit media" — those shrink the sheet and every degree with it.
Card stock or a transparency sheet keeps the edge straight. Plain paper works; just keep it flat.
Measure the ruler printed under the protractor with a tape or ruler. It must read exactly 10 cm (100 mm). If it does not, the printer scaled the page — reprint at 100%.
Cut along the outer edge. Optionally cut out the dashed centre window on the 180° version so you can see the vertex through it, and poke a pin hole at the crosshair.
The 10 cm ruler is the whole quality check. A protractor's degrees are angles, so uniform scaling does not change them — a 90% print still reads 90° at a right angle — but the ruler tells you the printer did not distort the sheet, and it turns the base edge into a real 10 cm ruler you can use for the drawing itself. On US Letter, A4 or any larger paper the sheet fits with margins to spare; the 180° version is 12 × 8.2 cm and the 360° version 12 × 12.8 cm including the ruler.
A paper protractor works exactly like a plastic one. Place the centre crosshair on the vertex (the point where the two lines meet), turn the sheet so the baseline runs along one side of the angle, and read where the other side crosses the curved scale. On the 180° version, read the scale whose 0° sits on the side you aligned — outer if that side points right, inner if it points left — and check the answer against a square corner: an angle narrower than 90° must read under 90. The step-by-step with diagrams, including drawing angles and measuring reflex angles, is in how to use a protractor.
Because the paper is thin, you get one advantage over plastic: lay it directly on a drawing and the lines show through, so the origin is easy to seat exactly. Two things to avoid: a crease across the scale, and reading from a curled sheet — flatten it under a book first.
A clear overhead transparency makes a see-through protractor you can align like a plastic one. Card stock gives a straight edge that survives a pencil case.
The dashed half-circle around the origin on the 180° sheet is a cut line. Removing it lets you see the vertex and both rays under the paper.
The SVG is free to print as many times as you need for a classroom or a workshop. Print one first and check the ruler before running the whole batch.
The 180° protractor is the one to print for homework, geometry class and most drawing: it is small enough to sit on a worksheet, and its two scales let you measure an angle opening to the left or to the right without flipping the sheet. Anything up to 180° reads directly; a reflex angle is the small angle on the other side subtracted from 360°.
The 360° protractor reads reflex angles and full rotations directly and has only one scale, so there is no inner/outer decision to get wrong. It is the better choice for bearings, compass headings, rotations in a diagram, or checking a pie chart — at the cost of covering more of the drawing.
Protractor turns your phone into a precision angle finder, level and inclinometer. Measure anything, anywhere.
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