Why Printed Rulers Come Out the Wrong Size

Guide · 4 min read

You print a ruler, measure it against a real one, and it's off by a few millimeters — sometimes more. This isn't a bug in the ruler; it's almost always one setting in your print dialog: "Fit to page" / "Shrink to printable area."

The fix: force 100% scale

1. Open the print dialog

   Ctrl+P (Windows/Linux) or Cmd+P (Mac).

2. Find the scale option

   Usually under "More settings" in Chrome/Edge, or a dedicated "Scale" field in Firefox and Safari.

3. Set it to exactly 100%

   Not "Fit to page," not "Shrink to fit" — the literal number 100.

4. Set margins to "None" or "Minimum"

   This avoids the page content being pushed or clipped near the edges.

5. Print a test page first

   Use our print accuracy checker — it prints a box sized to an exact credit card (85.6mm × 53.98mm) so you can verify against a real card before trusting any ruler.

Other common causes

• PDF viewers often have their own separate scale setting that overrides the browser's — check both if you save the ruler as a PDF first.
• Old or low-end printers can have a small amount of mechanical drift; a 1-2% error is common even at "100%" scale. Our accuracy checker will reveal this.
• Paper size mismatch — printing an A4-formatted ruler on US Letter paper (or vice versa) can trigger automatic scaling. Match the paper size selected in the print dialog to the paper actually loaded in the tray.

Why this doesn't affect on-screen digital rulers the same way

Printing is different from displaying on screen: paper has a fixed, known physical size, so software can map CSS units like centimeters and inches directly onto it — accurately, every time — as long as scaling is disabled. Screens have no fixed physical size relationship to pixels, which is why our digital ruler needs a manual calibration step instead.

Ready to try it? Build and print your ruler now that your printer is dialed in.