Actual size card viewer
Choose a card and compare its size on your screen. Calibrate with a bank card for a closer match to physical size.
Viewer
Match the outline to a standard bank card
Hold a standard bank or credit card flat against the screen with its left edge on the red outline's left edge. Adjust the outline until both right edges meet. Use a standard bank card, not a paper business card.
Use the slider for a first match, then the buttons or arrow keys for small adjustments.
Calibration details
Screen scale details
Uncalibrated: 3.78 CSS px per mm on this display. Grid squares are 10 mm.
The printed sheet carries a 100 mm check bar. Set the print dialog to 100 % scale.
The bar above should measure 100 mm. If it does not, set the print scale to 100 %.
Getting a reliable screen comparison
A browser cannot reliably determine your screen’s physical size. Match the calibration outline to a standard bank or credit card following ISO/IEC 7810 ID-1: 85.6 × 53.98 mm (3.37 × 2.13 in).
Card tolerance and edge alignment still affect the result. Recalibrate after changing monitors, zoom or display scaling, even if no prompt appears: two monitors can report the same settings despite having different physical sizes. Saved calibration expires after 180 days.
Printing at true size
Choose 100 % scale in the print dialog and turn off “fit to page.” Measure the printed check bar with a ruler. If it does not match its label, adjust the print settings before using the card outline.
What is stored
Calibration and display settings stay in this browser; nothing is sent to a server. If browser storage is unavailable, calibration lasts for the current page. Use “Clear calibration” to remove it, or clear the site’s browser data.
The ID-1 dimensions come from the ISO/IEC 7810, ID-1 summary (retrieved 2026-09-16); the ISO text itself is paywalled. See the W3C definition of screen and print units for the browser’s reference scale.