Printable Ruler (cm / inch)
Print a scale-verified ruler.
Print settings
Print this on the paper you normally use, then examine each section. What a healthy result looks like is described above each pattern on the sheet.
RunTheTests Printable Ruler (cm / inch) · print at 100% · plain paper
Ruler — print at 100%; verify against a real ruler
How this test page works
The ruler prints at true physical size when you print at 100%. A verification note lets you confirm the scale against a real ruler before trusting it.
What the results mean
- Verify the scale
- Always print at 100% (not "fit to page") and check the first few centimetres against a known ruler, since printer margins can shift scaling.
Common problems and fixes
- The printed ruler is a few percent short
- The print dialogue scaled it — the default on most systems, and fatal here. "Fit to page" and "Shrink oversized pages" resize the sheet by a few percent to clear the unprintable margin, so a ruler printed that way is quietly wrong along its whole length. Set scaling to 100% or "Actual size".
- It measures correctly in one direction and not the other
- Some printers scale differently along the feed direction than across it, usually because of paper slip. If one axis is right and the other is not, the ruler is unreliable for precise work on this printer — reprint on heavier stock, which slips less, and verify both axes again.
- I need to measure something longer than the page
- Print two sheets and align them at a marked point rather than butting the paper edges together, since the unprintable margin means the scale does not run to the edge of the sheet. Aligning on a printed graduation rather than on the paper itself keeps the error from accumulating.
Frequently asked questions
Is a printed ruler accurate?
It can be, if you print at exactly 100% scale and your printer is not silently shrinking to fit its margins. Always verify the first centimetres against a real ruler — the note on the sheet reminds you why.
How accurate can a printed ruler be?
Good to well under a millimetre over a short span if it printed at exactly 100% and you verified it, which is enough for most practical measuring. It will not match a steel rule over 30 centimetres, because paper stretches slightly with humidity and the printer's own scaling has a tolerance.
Why not just measure on screen?
Because a browser has no reliable idea of your display's physical size. CSS pixels are a reference unit rather than a real one, and the same on-screen ruler renders at different physical sizes on different monitors at different scaling settings. Paper, printed at a verified 100%, is the one output whose scale you can check.