How to Test If Your Printer Prints to Scale (Free Ruler Test)

Published 16 July 2026

If you have ever printed a sewing pattern, a woodworking template or graph paper and found it was almost the right size but not quite, you are not imagining it. Most printers quietly shrink pages by a few percent, and for anything you actually measure, that small error matters. This guide explains why it happens and how to prove — in under a minute — whether your printer prints at true scale.

Why printers shrink your pages

Almost every printer has a small unprintable border around the edge of the paper — typically 3 to 6 mm — where the rollers grip and the ink heads cannot reach. To avoid clipping anything, browsers and PDF readers default to a setting called “Shrink to fit” or “Fit to printable area”. This scales the whole page down slightly so it fits inside that border. The result: a document designed to be 210 mm wide (A4) prints at maybe 200 mm, and every measurement on it is now about 4.5% too small.

For a birthday banner nobody notices. For a 1:1 pattern, a scale drawing, a game board sized to real pieces, or graph paper where each square should be exactly 5 mm, it ruins the print. The fix is simple once you know the two settings to change.

The fix: 100% scale and no margins

You need to override two things in the print dialog:

• Scale = 100% (or “Actual size” / “Default”). Never “Fit” or “Shrink oversized pages”. This is the single most important setting.
• Margins = None (or Minimum). This stops the software from adding its own padding on top of the scaling.

With those two set, a page defined in real millimetres will print at its true physical size, assuming your printer itself is honest. That last part is worth verifying, which is what the ruler test is for.

How to run the ruler test (the 50 mm square test)

The idea is dead simple: print something whose size you know, then measure it with a real ruler. If it matches, your settings are correct. If it is off, you know by exactly how much.

1. Open the printer calibration page. It draws a ruler along with a 50 mm test square, both defined in exact millimetres.
2. Print it with Scale set to 100% and Margins set to None.
3. Take a real ruler or tape measure and measure the printed test square. It should read exactly 50 mm across, and the printed ruler should line up with your physical ruler mark-for-mark.

If the square measures 50 mm, congratulations — your printer and settings are spot on, and everything else on printsheet.io will print at true scale. If it is out, read on.

Browser-specific print dialog tips

Google Chrome / Edge

In the print dialog, click More settings. Set Scale to Default (which is 100%) or choose Custom and type 100. Set Margins to None. Untick “Fit to page” if it appears. Edge uses the same Chromium dialog, so the steps are identical.

Mozilla Firefox

Click More settings in the print preview. Set Scale to 100% (not “Fit to page width”). Set Margins to None. Firefox occasionally re-enables “Shrink to fit” after an update, so check it each time for measured prints.

Safari (macOS)

Safari hides the scale control. In the print dialog, make sure Scale is set to 100% and that “Scale to fit” is off. Choose your paper size explicitly (for example A4), and if you see a header/footer option, turn it off so Safari does not add its own margins.

Adobe Acrobat / PDF readers

If you saved a sheet as PDF first, the reader has its own scaling. In Acrobat's print dialog choose Actual size (not “Fit” or “Shrink oversized pages”). This is the most common reason a PDF that was correct on screen prints too small.

What to do if it is still off

If you have set 100% and no margins and the square still is not 50 mm, work through these:

• Wrong paper size selected. Printing an A4 layout onto US Letter (or vice versa) makes the driver rescale. Match the dialog's paper size to the paper actually in the tray.
• A second scaling step. If you printed a saved PDF, both the browser (when saving) and the PDF reader (when printing) can scale. Check both are at 100%/Actual size.
• Printer driver “fit to page”. Some drivers have their own fit setting in the Properties/Advanced panel, separate from the browser. Turn it off.
• Consistent small error. If every print is off by the same percentage (say always 3% small), that is a driver default rescaling; adjusting the browser scale slightly to compensate (e.g. 103%) is a last resort, but fixing the driver setting is better.
• Borderless mode. Some inkjets have a “borderless” photo mode that enlarges the page instead. Turn it off for documents.

Re-run the ruler test after each change so you know immediately whether it worked.

Why every printsheet.io template is drawn in real millimetres

The reason the ruler test works at all is that our sheets are not fuzzy images — they are drawn as vector graphics in true physical units, with the exact page size embedded. Get your printer honest once, and graph paper, dot grid, sewing grids, game boards and every other template will all come out the correct size. That is the whole point.

Frequently asked questions