Everyone has struggled with a crappy iPhone signal, but have you ever wondered what the signal strength bars really mean?

Tech Insider has made a video about a trick that can show how strong your iPhone signal actually is. It’s really cool and it works!

First, enter this code and press the call button.

Then, hold down power/lock until the phone goes to the “power down” screen. Next, hold the home button for six seconds.

You’ll then be taken back to your homescreen, where instead of bars or dots, a number is displayed to indicate signal strength.

Since the values are negative, the closer the number is to zero the stronger your signal is. A good signal is in the -44 to -77 range, or the equivalent of five bars. A weak signal would be in the -102 to -120 range.

In this case, a -99 was equal to three dots in signal strength. You can also toggle between the two displays simply by tapping the number or signal indicator.

Now, with this tool you will know exactly what your iPhone’s signal is!

Thanks to BuzzFeed!