PDF Prints Smaller Than 100%? Print at Actual Size and Check the Scale
A PDF can say it is A4 and still come out of the printer 4% too small. The cause is almost never the PDF. It is the print dialog quietly shrinking the page to fit the printable area. Here is how to print at actual size, and how to tell a wrong PDF from a printer that scaled a correct one.
The quick test: a known 100 mm line
Download the print at actual size test sheet (A4 or US Letter). It has a 100 mm line, a 100 mm square and a 4 inch line. Print it with the scale options below, then lay a physical ruler on it.
- About 100 mm: your printer and settings are fine.
- Shorter, for example 96 mm: the page was shrunk to 96%.
- Longer: the page was enlarged, for example by a mismatched paper size.
Print at actual size
- Chrome and Edge: in the print dialog open More settings and set Scale to Default (or Custom 100), not Fit to page.
- Adobe Acrobat and Reader: Page Sizing and Handling, then Actual size.
- macOS Preview: Scale 100% and untick Scale to Fit.
- Firefox: Scale 100%, not Shrink to fit.
Separate the PDF from the printer
Open the same file in PdfRuler and measure it. The ruler works in PDF points, so it shows what the file contains no matter how it is printed. If the PDF measures 100 mm and the paper measures 96 mm, the printer scaled it. If the PDF itself measures 96 mm, the file was made at the wrong size, and printing will not fix that. See how to find the page size of a PDF.
Correct a stubborn scale
Divide 100 by the length you measured and multiply by 100. A line that measures 96 mm needs a custom scale of about 104.2%. Print again at that scale and re-measure. Also check the paper size: a Letter file printed on A4 gets rescaled by many printers, see US Letter vs A4.
Before you send a file to a printing service, run through the print-ready checklist, and use the paper size reference for exact dimensions.
Frequently asked questions
Why does my PDF print smaller than 100%?
The print dialog is usually set to Fit to page or Shrink to fit, which rescales the page to the printable area. Choose Actual size, 100% or Default scale.
How do I know if the PDF or the printer is wrong?
Measure the PDF in PdfRuler, then print a test sheet and measure the paper. If the PDF is right and the paper is not, the printer scaled it.
What scale fixes a page that prints at 96%?
About 104.2%: divide 100 by the measured length and multiply by 100, then print again and re-measure.
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