A ruler is something that can be really handy to have, yet something that you almost never have when you need it. With the Ruler app, you can measure anything on-the-go with the mobile phone already in your pocket! Great for measuring short things. You can measure long things, too, but it requires doing the following:
(1) Align the starting edge of the object with the starting edge of the screen.
(2) Tap the screen toward the end of the visible ruler to place the marker line on the screen.
(3) Place an available finger on the object and align it with the marker line (to remember that precise location).
(4) Tap the right button to advance the ruler. This moves the marker line (along with the rest of the ruler) toward the start of the screen.
(5) Slide your phone so the new position of the marker line is aligned with your finger that remembered the old position.
(6) Repeat steps 2-5 until you’ve reached the end of the object.
Ruler has a calibration button for adjusting the space between its lines, as not all Windows Phone screens are guaranteed to be the same size.