Printable Ruler
Make a true-to-scale paper ruler in centimeters, millimeters or inches and download it as a print-ready PDF. A calibration square on every page lets you confirm the printout is exactly the right size before you measure anything.
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Print at 100% / Actual size. Turn off “Fit to page”.
How to use the Printable Ruler
- Choose the scale: centimeters, inches or both edges on one ruler.
- Set the length with a preset (15 cm, 30 cm, 6 in, 12 in…) or type any length in range.
- Pick the paper size and how many rulers you want on the page. The preview shows the exact layout.
- Download the PDF and print it at 100% / Actual size with “Fit to page” turned off.
- Check the calibration square with any ruler or a bank card, then cut the strips out along the gray outline.
How to print a ruler at the exact size
A PDF stores real-world dimensions, so a ruler printed from this tool is true to scale as long as the printer does not resize the page. Printers and PDF viewers often shrink pages by 3–6% by default to fit their printable area, which turns a 15 cm ruler into a 14.2 cm one. To avoid that:
- Chrome / Edge: More settings → Scale → Default or Custom 100. Do not choose “Fit to printable area”.
- Adobe Acrobat Reader: Page Sizing & Handling → Actual size.
- macOS Preview: Scale 100%, untick “Scale to fit”.
- Paper size in the print dialog must match the paper chosen here (A4 or Letter), otherwise some drivers rescale the page.
Then measure the calibration square. If it is not exactly 50 mm (or 2 in), compute the scale your printer applied, scale = measured ÷ expected, and enter 100 ÷ scale % as a custom scale. Example: the square measures 48.5 mm → 48.5 ÷ 50 = 0.97 → print at 100 ÷ 0.97 ≈ 103%.
Ruler markings explained
| Mark | Metric value | Inch value | Tick on this ruler |
|---|---|---|---|
| Smallest metric tick | 1 mm | 0.0394 in | Shortest line |
| Half centimeter | 5 mm | 0.197 in | Medium line |
| Centimeter | 10 mm | 0.394 in | Longest line with number |
| 1/16 inch | 1.5875 mm | 0.0625 in | Shortest line |
| 1/8 inch | 3.175 mm | 0.125 in | Slightly longer |
| 1/4 inch | 6.35 mm | 0.25 in | Medium line |
| 1/2 inch | 12.7 mm | 0.5 in | Long line |
| 1 inch | 25.4 mm (exact) | 1 in | Longest line with number |
The inch has been defined as exactly 25.4 mm since 1959, which is why the inch edge of the dual ruler lines up with the metric edge at 127 mm = 5 in.
Gluing a long ruler together
A 30 cm or 12 inch ruler is longer than A4 or Letter paper once printer margins are included, so it is printed in parts. Cut part 1 exactly on its last line (the right edge of the strip is the end mark), cut part 2 around its outline including the gray glue tab, put glue on the tab and lay part 1 on top so its end edge sits exactly on the first mark of part 2. Card stock or a strip of clear tape on the back makes the joined ruler much stiffer.
Frequently asked questions
How do I make sure the printable ruler prints at the correct size?
In the print dialog choose Scale 100% or Actual size and turn off Fit to page, Shrink to fit and Scale to fit. After printing, measure the calibration square: it must be exactly 5 cm (or 2 in) on every side. If it is smaller or larger, the printer scaled the page and the ruler is not accurate.
Can I print a 30 cm ruler on A4 or Letter paper?
A 30 cm scale plus the margins a printer needs is longer than A4 (29.7 cm) and Letter (27.94 cm) paper, so the tool splits it into two 15 cm parts with a glue tab. Cut part 1 flush at its end and glue it onto the tab of part 2 so the end lines meet. Choose Legal or A3 paper to print it in one piece.
How accurate is a paper ruler?
The PDF geometry is exact to well under 0.01 mm. In practice the accuracy depends on your printer, which is usually within about 0.5 mm over 20 cm when printing at 100%, and on how cleanly you cut the strip. Paper also expands slightly with humidity, so use a printed ruler for everyday measuring rather than precision engineering.
Why does the ruler start a few millimeters from the edge of the strip?
A small lead-in before the zero mark means the zero line stays visible and accurate even if you cut the strip a little unevenly. Line the zero mark, not the paper edge, up with the start of the object you are measuring.
What is the difference between 1/16, 1/8 and 1/10 inch markings?
Standard US rulers divide each inch into 16 parts (1/16 in = 1.5875 mm). The 1/8 option gives a cleaner scale for children or quick work. The 1/10 option is an engineer's decimal scale where each tick is 0.1 in (2.54 mm).
Can I check a printed ruler without another ruler?
Yes. Turn on the bank card outline: every standard credit, debit or ID card (ISO/IEC 7810 ID-1) is 85.60 × 53.98 mm. Place a card on the printed outline; if it matches exactly, your print is to scale.
Is my data uploaded anywhere?
No. The PDF is drawn in your browser and downloaded directly. Nothing is sent to a server and there is no sign-up.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.