Mobile ruler
Calibrate with a card and turn your phone into a centimeter or inch ruler.
Auto-estimated device scale：Default screen estimate
Auto-estimated; manual calibration available · 3.78 px/mm
Search and use guide
Mobile ruler
Calibrate your phone screen with a card and display a near actual-size centimeter or inch ruler. privacy-first-browser-tooling
Who it helps
- A mobile-first online ruler with card calibration, manual tuning, centimeter/inch units, and horizontal/vertical marks.
- After calibrating pixels per millimeter with an 85.60mm card width, the tool draws millimeter or 1/16-inch marks. Uncalibrated values are estimates.
- place a card on the calibration block, adjust the slider until widths match, then measure small objects from the 0 mark.
What you can enter
- place a card on the calibration block, adjust the slider until widths match, then measure small objects from the 0 mark.
- After calibrating pixels per millimeter with an 85.60mm card width, the tool draws millimeter or 1/16-inch marks. Uncali
How to read results
After calibrating pixels per millimeter with an 85.60mm card width, the tool draws millimeter or 1/16-inch marks. Uncalibrated values are estimates. privacy-first-browser-tooling
Data and privacy
GoGo Tools records analytics by tool slug only and does not include your input values. privacy-safe-analytics-only
Feedback
How can we improve this tool?
Send a suggestion or bug report for this tool.
FAQ
Is the mobile ruler accurate?
After calibration it is useful for everyday estimates. Use a physical ruler for official measurements.
Why calibrate with a card?
Most credit and transit cards are 85.60mm wide, making them easy reference objects.
Is data uploaded?
No. Calibration and drawing run in your browser.
Can it measure inches?
Yes. Switch between centimeter and inch marks.