Check that your printer prints at real size

Download the calibration PDF and print it with the scale set to “Actual size” or “100%”. Do not use “Fit to page”.

Measure the two rulers with a ruler of your own: each should be exactly 100 mm long, and the card frame 85.6 × 54 mm. A difference of more than 1 mm means the printer or print dialog is scaling the page.