With 'Must Have Ruler' your phone becomes amazing tool for measuring distance and height of any object inside or outside.

The only rule is you are standing on the level of the object, but even that can be fixed by setting the height of your phone vs. bottom of the object being measured.

Follow these simple steps for measuring: Hold phone 1.55 m from the ground (if you hold it higher or lower see bellow how to set phone's height), and locate bottom (point touching ground) of the object in the center of camera preview. Then click "FIX DISTANCE" and rotate camera up or down (but on the same height), to locate top of the object in center of camera preview. Distance and height are displayed automatically.

How to change phone's height: click "PHONE", then rotate left or right to adjust value. Click this button again when you are done.

And that's all. Happy measuring.

App uses phones gravity sensor to calculate angle, does not use data transmission and only stores height of the phone.