توضیحات:

This app creates a standardized ruler on your screen. With that you always have a little measure in your pocket.
Most android devices are standardized by default and you can start to measure directly. If that however is not the case for you, the app also allows to calibrate the units manually.

Screen Ruler is free with a little banner ad.

If you want to support me and also remove the ad, feel free to take a look at the pro version of this app.