Printable Ruler — Actual Size
Print a 30 cm and 12 inch ruler at actual physical size on any A4 or Letter sheet. Includes a credit card verification box so you can confirm accuracy after printing.
About This Printable Ruler
This page generates a 30 cm ruler and a 12 inch ruler using CSS absolute units (cm) — meaning the physical size is determined by your printer's interpretation of CSS, not your screen's PPI. At 100% print scale, the rulers print at true physical size on any printer.
The credit card verification box (85.6 × 54 mm — the ISO 7810 ID-1 standard used for all credit cards, debit cards, and IDs worldwide) lets you confirm accuracy immediately after printing. If the card doesn't match the box, check that your browser printed at exactly 100% scale.
Frequently Asked Questions
How do I print a ruler at actual size?
Click the Print Ruler button on this page. In your browser's print dialog, set the scale to exactly 100% — never use "Fit to page" or "Shrink to fit". After printing, verify with a physical credit card (85.6 mm wide) against the verification box on the printout.
Why is my printed ruler not the right size?
The most common cause is print scaling. Make sure scale is set to 100% in your print dialog. On Chrome: More settings → Scale → 100. On Firefox: Page Setup → Scale → 100%. On Safari: uncheck "Scale to fit". Also check your paper size matches (A4 or Letter).
Is the printable ruler accurate?
Yes — browsers render CSS cm and mm as absolute units at print time, so the rulers print at their exact physical size regardless of screen PPI. The verification box (credit card size: 85.6 × 54 mm) on the printout lets you confirm accuracy immediately.
Can I print both inch and cm rulers on one page?
Yes — this page prints both a 30 cm ruler and a 12 inch ruler on a single A4 or Letter sheet. Both rulers include a verification credit card box so you can confirm each one after printing.
What paper size should I use?
Use A4 landscape (297 × 210 mm) or US Letter landscape (279 × 216 mm). This page prints in A4 landscape by default. Portrait A4 is only 210 mm wide — too narrow for a 30 cm ruler. After printing, always verify with the credit card box.
Can I use a printed ruler for precise work?
Yes, with caveats. Home inkjet and laser printers are typically accurate to ±0.5 mm when printing at 100% scale. For work requiring tighter tolerances (e.g. PCB layout), verify against a calibrated physical ruler after printing.