Shared foundation

Calibrate your display.

All tools share one pxPerMm scale. Credit card matching is recommended. Nothing is scanned or uploaded.

Calibrate your display for best accuracy. Verify critical measurements using appropriate physical measuring equipment. If you resize the window or move to another display, you may see a recheck prompt.

JavaScript is required to calibrate

Calibration controls need JavaScript. Enable it, then return to this page.

Credit card

Recommended

Place a standard credit or debit card against the screen and resize the outline until the edges match.

We only use the physical size of the card. Nothing is scanned or uploaded.

ID-1 · 85.60 × 53.98 mm

320 px

Screen diagonal

Enter your screen’s diagonal size in inches. This approximates physical scale from the display aspect ratio.

Custom diagonal (inches)

Automatic estimate

Uses the browser’s CSS reference pixel density. This is an estimate only — browsers cannot reliably identify every physical display.

Estimated

Encourage manual verification with a credit card for best accuracy.

Next: choose a tool or read how it works.