PrintableRuler.onlinePrintable Protractor
This free printable protractor is a true-to-scale 180° protractor, 16cm across, for measuring and drawing angles. It's ready to print at home for school, drafting, woodworking, or any project that needs an accurate angle reading. Just set your printer to 100% scale — no "fit to page" — and every degree mark lines up exactly as drawn.
Set your printer's scale to 100% and disable "Fit to page" before printing.
How to use a protractor
Line up the flat baseline of the protractor with one side (ray) of the angle you're measuring, with the center point exactly on the angle's vertex. Read the degree value where the second ray crosses the curved edge.
Tips for accurate angle measurements
- Print at 100% scale — a scaled protractor will read every angle incorrectly.
- For angles greater than 180°, measure the remaining reflex angle and subtract from 360°.
- Glue or tape the print to thin cardboard for a sturdier, reusable protractor.
Need straight-edge measurements too? Build one with the custom ruler builder, or try the millimeter ruler.
Printable Protractor Tips
- Verify your printer first. Run the credit-card accuracy test before trusting a single angle reading — a "Fit to page" print will read every angle wrong, even though the protractor still looks correct at a glance.
- Mount it for repeat use. Glue or tape the printed sheet to thin cardboard or a cereal-box panel, then trim along the outer arc with scissors or a craft knife for a rigid, reusable protractor.
- Punch the vertex for pinpoint accuracy. A small pinhole at the center dot lets you mark the exact vertex through the paper before lining up the baseline — more precise than eyeballing it.
- Extend the baseline for long rays. If the angle's sides are longer than the protractor, lay a ruler along the baseline edge first, then slide the protractor to the vertex — the ruler keeps the reference line straight.
- Reading past 180°? This protractor covers a half-circle. For reflex angles, measure the smaller angle on the other side and subtract it from 360°.
- Keep it flat when storing. Paper and even cardboard-backed protractors can warp over time — store it flat inside a book or folder rather than rolled up, so the arc stays true next time you need it.
Frequently Asked Questions
How do I measure an angle with a printed protractor?
Place the center dot exactly on the vertex of the angle, and line up the flat baseline (the 0°–180° edge) with one of the angle's rays. Read the number on the curved scale where the second ray crosses it — that's the angle in degrees.
Why does my angle read wrong even though the protractor looks fine?
The most common cause is a printer silently scaling the page to "fit," which stretches or shrinks the arc slightly and throws off every reading. Run the credit-card accuracy test first and set your printer to 100% / "Actual size" with no scaling.
How do I measure a reflex angle (greater than 180°)?
This protractor covers a half-circle (0°–180°), so for a reflex angle, measure the smaller angle on the other side of the same two rays and subtract that reading from 360°.
What's the difference between this and a full 360° protractor?
A 180° protractor is the standard classroom and drafting tool — it measures any angle from 0° up to a straight line, and reflex angles are found by subtracting from 360° as above. A full-circle protractor reads reflex angles directly, but is less common and not usually needed for everyday geometry, drawing, or woodworking tasks.
Can I use this protractor to draw angles, not just measure them?
Yes. Draw one ray first, place the center dot on its start point with the baseline along the ray, then make a small mark at the degree you want on the curved scale. Connecting the vertex to that mark gives you the second ray at the exact angle.
How accurate is a paper protractor compared to a plastic one?
Just as accurate, as long as it's printed at true 1:1 scale — the geometry is identical to a molded plastic protractor. The main practical difference is durability: paper is more prone to tearing or warping, which is why mounting it on cardboard is recommended for repeat use.
Can I resize this protractor to a bigger or smaller radius?
Not from this page directly — it's fixed at a 16cm (80mm radius) true-to-scale size so the printed degree marks stay accurate. Scaling it up or down in your print dialog would distort the arc and make every angle reading wrong, so keep the print at 100% rather than resizing.
What can I use a printable protractor for?
Common uses include geometry and math homework, drafting and technical drawing, woodworking and miter cuts, sewing and pattern angles, and any DIY project where you need to measure or lay out an exact angle without owning a physical protractor.