Screen Calibration

To ensure accurate on-screen ruler measurements, calibrate your display using a common object.

Use one of the following:

  • Credit card
  • US $1 bill
  • A4 paper
  • Letter-size paper

How to calibrate:

  1. Place the object against your screen.
  2. Adjust the PPI (Pixels Per Inch) using the input box or the + / − buttons.
  3. Match the on-screen size to the real-world size.
  4. Once matched, your ruler will display precise measurements.
CreditCardBANK of AUROCHS
3141 5926 5358 9793
06 / 15
Width: 3.37 in (85.6 mm)
Height: 2.125 in (53.98 mm)
Graduation of an inch

Rotate your device

Ruler.Tomorrow works best in landscape. Turn your phone sideways for an accurate, full-width ruler.