Millimeter is the best free screen ruler. Full screen is available for measurements. There are no ads in the app and unnecessary permissions. Manual calibration is available, so any device can be calibrated for accurate measurements.
- German, Russian, Japanese and French languages.
More about app: http://goo.gl/304nJB
More Features in Pro: http://goo.gl/qkDDfK
1.0.12 - fix for not showing values on some devices.
1.0.11 - small bug fix and menu button integrated
1.0.10 - stability improvement.
1.0.9 - save and keep app settings for the next launch
1.0.8 - fractions for inch units; German, Russian, Japanese, French languages support