Printable Ruler
Calibration checked · How we check
Inches to sixteenths on the top edge, centimeters to the millimeter on the bottom. Mark height carries the division the way a tape does — the longest lines are whole units, the shortest are sixteenths and millimeters.
Before you print
- Set the print scale to 100% — not “fit to page”, which shrinks by a few percent.
- Choose landscape. A 12-inch ruler does not fit across a portrait page.
- Print, then measure the reference bar below with a ruler you trust.
- If it is not exactly 100 mm, type what you measured and print again.
Printed at 100% on A4 or US Letter. Paper stretches with humidity, so re-check the reference bar if precision matters.
What it is for
- —Checking a measurement when the tape is in the other van.
- —Teaching fractions — the sixteenth marks are labelled by length, not by number.
- —Measuring something flat that a rigid ruler cannot reach around.
Why the calibration step exists
The drawing is exact — every mark is placed in absolute units, so a millimeter in the file is a millimeter on paper. What is not exact is the path from file to sheet. Print dialogs default to fitting the page, which rescales by a few percent, and printers differ from each other regardless. Nothing in a web page can detect that; only measuring the printed sheet can. The reference bar is there so the error is visible in one look, and the scale field is there so you can cancel it out.