No. 20 of 23

Printable ruler, actual size

Sometimes you need a ruler you can cut out, tape to a box or slip into an envelope. This sheet prints at true scale on A4 or US Letter, with long rulers down both edges, two short ones, a bank-card outline and a pair of grids that show straight away whether the printer shrank anything.

Download PDF (Letter)

Print at 100% (“Actual size”), not “Fit to page”. The PDF is the safest route if your browser adds its own margins.

RulerNestLetter · 215.9 × 279.4 mmPrint at 100% (Actual size). The card outline must match a real bank card.1234567891011121314151617181920212223cm123456789inScale checkBank card85.60 × 53.98 mm100 mm4 in12345678910111213cm12345in50 × 50 mm · 1 mm2 × 2 in · 1/8 inrulernest.com · Cut along the dashed lines
Preview of the printable sheet (not to scale on screen)

Scale check

Printer scale–
What to do–

Key: / jumps to the first field

Results are for information only.

How to use it

  1. Pick your paper, A4 or US Letter, then print the sheet or download the PDF.
  2. In the print dialog, set Scale to 100% or “Actual size”. Turn off “Fit to page” and “Shrink oversized pages”.
  3. Before you cut, lay a bank card on the card outline or measure the 100 mm bar. If it's off, type what you measured into the scale check below and print again at the corrected scale.

How it works

The sheet is drawn in millimeters, not pixels. Every tick is a vector line placed at an exact distance from zero, and the page asks the browser for a paper size of exactly 210 × 297 mm (A4) or 215.9 × 279.4 mm (Letter), with no margins added. As long as nothing in between rescales it, a centimeter on paper is a centimeter. The scale check works backwards: you measure a printed reference of known length, and the calculator divides your measurement by the true length to get the scale the printer actually used.

scale = measured ÷ true length × 100 · correction = true length ÷ measured × 100

Worked example

You print the sheet and the 100 mm bar measures 97 mm. The printer worked at 97 ÷ 100 × 100 = 97.0%. To cancel it out, print again with the scale set to 100 ÷ 97 × 100 = 103.1%, and the bar comes out at 100 × 0.97 × 1.031 = 100.0 mm. Another common case: the A4 PDF printed on Letter paper with “Fit to page” on. The height decides the shrink, 279.4 ÷ 297 = 94.1%, which quietly turns a 25 cm ruler into 23.5 cm.

Assumptions and limits

  • Many print dialogs only take whole numbers, so 103.1% becomes 103%. That leaves about 0.1 mm of error over 100 mm, which is fine.
  • A printer can stretch one direction a bit more than the other. The long rulers run down the page and the check bars run across it, so if accuracy matters, measure one of each.
  • Ordinary paper changes size by roughly 0.1 to 0.2% with humidity. For a ruler you plan to keep, print on card stock or laminate it.
  • Each ruler starts at its dashed cut line. Cut on the line, not beside it, or every reading will be off by the width of your cut.

Related tools

Frequently asked questions

Why does my printed ruler come out too small?

Nearly always because the print dialog shrank the page to fit the printable area. “Fit to page” usually prints at 94 to 97%. Pick 100% or “Actual size” and it comes out right.

How accurate is a printed ruler?

Once the scale check passes, expect about ±0.5 mm over 10 cm from an ordinary laser or inkjet printer. Paper moves a little with humidity, so it's great for crafts, ring sizing and quick checks, not for machining.

Can I print the A4 sheet on Letter paper?

Not at 100%. A4 is 17.6 mm taller than Letter, so the bottom gets cut off or the printer shrinks the whole page. Use the sheet that matches the paper in your tray.