Printable Ruler
A printable ruler drawn at true size: centimetres with millimetre marks, inches with sixteenths, or both, with a bank-card outline to check that your printer kept the scale. Choose the units and the length and print at actual size.
Your sheet
Printing: choose Actual size or 100%, not “Fit to page”, so 1 cm prints as 1 cm. How to check.
How is the ruler kept accurate?
Every mark is placed in millimetres: the k-th millimetre mark at k mm, the k-th sixteenth-inch mark at k × 25.4 ÷ 16 = k × 1.5875 mm. The sheet is the exact paper size, so a print at 100% is true.
Worked example. The 6 inch ruler is 6 × 25.4 = 152.4 mm long, almost exactly the 15 cm ruler above it, which is how you can see that 6 inches is a little more than 15 cm. The bank-card box is 85.60 × 53.98 mm with 3.18 mm rounded corners, the ISO/IEC 7810 ID-1 size every payment card follows.
Checking a print in five seconds
Lay any payment, library or loyalty card on the dashed box. If the card’s edges sit on the dashes, the print is true and every other sheet from this site will be too. If the card is bigger than the box, the printer shrank the page; if smaller, it enlarged it. Both are fixed by choosing Actual size.
Centimetres and inches on one sheet
With both rulers printed one above the other, the conversions are visible: 1 inch sits at 2.54 cm, 10 cm at just under 4 inches, 30 cm at 11.8 inches. It is a quick way to learn the relationship without a calculator.
Other true-size sheets
Every sheet on this site is drawn the same way, so once your printer passes the card check you can trust the 1 cm squares on grid paper, the quarter-inch graph paper and the staff heights on blank sheet music.
Questions about the printable ruler
Will the ruler really be the right size?
Yes, if the print is at actual size. The ruler is drawn in millimetres and the page is set to your paper size, so a printer at 100% scale prints it true. The bank-card box under the rulers is the check: any payment card is 85.60 × 53.98 mm, and if yours fits the dashed box exactly the ruler is accurate.
What if the card does not fit the box?
Your printer scaled the page. In the print dialog turn off “Fit to page”, “Shrink to fit” or “Scale to fit” and choose Actual size or 100%, then print again. Our guide walks through it for Windows, Mac, iPhone and Android.
How long can the ruler be?
Up to 30 cm or 12 inches. A 15 cm or 6 inch ruler fits A4, Letter and larger pages in portrait (A5 is too narrow in portrait; turn it landscape). 20 cm and 8 inches need landscape. 30 cm (300 mm) and 12 inches (304.8 mm) are longer than A4 or Letter even sideways, so they need Legal, A3 or Tabloid in landscape; a ruler that does not fit the page is left off.
How fine are the marks?
Millimetres on the centimetre ruler, with longer marks at 5 and 10 mm. Sixteenths on the inch ruler, with longer marks at eighths, quarters, halves and inches.
Can I use it as a tape or a scale bar?
Print on card and cut along the edge for a flat ruler. For curves, print on paper and bend it. For a photograph, place the printed ruler in the shot as a scale bar.