Printer · about 2 minutes
Make every printout measure true
- Print the test sheet at 100%. Paper in your printer
In the print dialog choose Scale 100% / Actual size — the point is to measure what your printer really does.
- Measure the long horizontal bar with a ruler (bar A is 100 mm). Your ruler
- Which red margin lines printed on all four sides? Smallest line that printed everywhere
- Name it and save.
Saved only in this browser. Every PDF you download from PrintablePapers will be corrected for this printer.
Screen · optional
Make “True size” exact on this screen
Hold a bank card, ID card or library card against the screen and drag the slider until the outline matches its width (85.6 mm).
No card handy? Enter your screen size
Why printers aren't exactly 100%
Printers move paper with rollers, and rollers are never perfect. A typical home inkjet prints within half a percent of true size, but some are off by a full percent or more — over the length of a Letter page that is nearly 3 mm, enough to make a quilting template, a cross-stitch grid or a scale drawing visibly wrong. The error is usually slightly different across the page (the print-head direction) than down it (the paper-feed direction), which is why the test sheet has a horizontal and a vertical bar.
On top of the mechanical error, print dialogs love to “help”. Fit to page shrinks the whole page so nothing falls into the unprintable border, and many drivers turn it on by default. That alone takes 3–6% off every measurement. The wizard spots that pattern and tells you, instead of quietly baking the mistake into your correction.
What the correction does to your files
Each PDF still declares exactly the paper size you chose, so your printer doesn't switch trays or rescale. Inside each page we apply a tiny scale about the centre — for example 100.8% across and 100.4% down — that cancels your printer's error. Lines that were 6.35 mm apart in the file arrive on paper 6.35 mm apart.
Calibration is per printer and per browser. If you print from a laptop and a phone, run it on each. If you change paper type or have the printer serviced, run it again — it only takes a couple of minutes.
Checking a printout without calibrating
You don't need the wizard to check a sheet: measure across ten squares of any grid and compare with the spec table on that sheet's page. Ten quarter-inch squares are 63.5 mm; ten 5 mm squares are 50 mm. Within half a millimetre is excellent.
Frequently asked questions
Why does my printer print too small?
Nine times out of ten the print dialog is set to Fit to page or Shrink oversized pages, which reduces the page by 3–6% so it fits the printable area. Set the scale to 100% / Actual size. The test sheet here tells you which case you are in.
How does the calibration correct my printouts?
We compare what you measured with what the bar should be and store the ratio (for example +0.8%). Every PDF you then download has a matching scale built into each page, so the printer's error cancels out. The paper size in the PDF never changes.
Is my calibration uploaded anywhere?
No. It is saved in your browser's local storage on this device only. Clearing site data removes it; you can also reset any printer below.
Do I need a special ruler?
Any decent ruler works. A steel ruler or a quality school ruler is accurate to about a quarter of a millimetre, which is all you need. Measure from the very start to the very end of the black bar.
What are the red margin lines for?
They sit 3, 5, 8 and 10 mm from each paper edge. Most printers can't print right to the edge; the smallest line that appears on all four sides is your printer's safe margin, which we keep lines away from.
Can I calibrate more than one printer?
Yes. Name each one (home inkjet, school laser…) and switch between them. The generator shows which printer it is calibrated for next to the download button.
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