Printer calibration sheet

One sheet of paper tells you whether your printer is secretly scaling everything by 96%.

Print this page using whatever settings your print dialog opens with. Then measure the rule below with a ruler or a tape. That is the whole test.

This rule is 100 mm long. If it measures 100 mm on paper, your printer is honouring true size.

50 mm square. Check both axes — a printer can be right on one and wrong on the other.

If it does not measure 100 mm

Find "Scale" or "Actual size" in the print dialog, set it to 100%, turn off "Fit to page", and print again. A common default is 96%, which shrinks everything by 4% — a sewing pattern that will not fit, passport photos that fail a ruler check at the counter. Every tool on this site that promises a physical size assumes you have done this once.

How it works

Print this page

Whatever settings your print dialog opens with — that is the point of the test.

Measure the rule

A ruler or a tape against the 100 mm line. Note what it actually reads.

Fix the scaling and repeat

Set the dialog to 100% or "actual size", turn off "fit to page", print and measure again.

Print dialogs default to "fit to page" more often than anyone expects, and a driver that scales silently is the single most common reason a correctly-made file comes out the wrong size. Nothing on screen can detect it, because the scaling happens after the file leaves the browser.

So this page prints a ruler and a square. Measure the ruler: 100 mm is 100 mm. If it is not, select "actual size" or "100%" in the print dialog, turn off "fit to page", and measure again. Every true-size tool on this site assumes that setting is right.

When people use this

Before printing a sewing pattern —— A pattern scaled by 4% makes a garment that does not fit, and you find out after cutting the fabric.
Before printing passport photos —— Photo specifications are checked with a ruler at the counter. Print the calibration sheet first and the sizes will hold.
Before printing a tiled poster —— Check once, then print thirty sheets with confidence rather than discovering the scale after the ink is spent.
After changing printer or driver —— A driver update can reset the scaling default. One sheet of paper re-establishes the answer.

Print at 100%, not "fit to page"

In the print dialog choose Actual size or 100% and turn off Fit to page. A driver that scales to 96% shrinks everything by 4% — invisible on screen, wrong on paper.

Check your printer first →

Frequently asked questions

How do I use it?

Print this page at whatever setting your dialog opens with, then measure the 100 mm rule with a ruler or a tape. If it reads 100 mm, you are done. If it reads 96 mm, find "Scale" or "Actual size" in the print dialog, set it to 100%, turn off "fit to page", and print again.

The rule measures 96 mm. Why 96%?

Because 96% is the common default in print drivers for the "fit to printable area" setting, derived from the unprintable border. It is a sensible default for a photograph and a destructive one for anything with a physical size.

Does the sheet need to be a particular paper size?

It is laid out for A4 and Letter, which are the two sheets people have. On A4 the rule is 100 mm; on Letter it is 100 mm as well, because the rule is drawn at its true length rather than as a fraction of the sheet.

Once I have calibrated, do I need to do it again?

Only after a driver update, a printer change, or a switch to a different browser — those are the events that reset a scaling default. Keeping the printed sheet in the paper tray as a reference costs nothing.