How much signal do you need for a cell booster to work?

As a general rule, no one puts in a cellular signal booster because they already have great signal. You put in a cell booster because you have dropped calls or slow internet speeds. You put in a cell booster because you need great cell service.

So, you might get a little frustrated when I tell you that you must have good cell service in order to get better cell service with a booster.

Hold on what now?

I didn’t say you needed awesome cell service in order to get better cell service with a booster. What I’m saying is that if your booster can’t even pick up a sketchy signal at all, it’s not going to do you any good. Cellular signal boosters have much bigger antennas than your phone and you can put that antenna high above the trees but it still needs some sort of signal in order to amplify it for you use.

How much cell signal is enough?

This sort of thing varies based on a lot of factors but the experts agree that in order to amplify a cell signal, you need to start with a signal that’s stronger than -100dBm. Cell signals are measured in dBm. One dBm is .001 watts. More than one dBm means something more than that and less than one means something less. -100dBm means 1/100th of a milliwatt, or .00001 watt. That’s how weak your signal can be and still have a cell booster work.

Specifically, it needs to be -100dBm when it gets to the cell booster. The signal strength can be affected by the type of antenna, how it’s aimed, how long the cable is from point to point, and the type of cable it is. The good news here is that because of that big antenna mounted up high, your cell booster is going to get more signal than your phone could.

How can you tell if you have enough cell signal?

You can start with using your phone. If you have an Android, you can use apps like Signal Strength which will give you some idea of what you’re receiving. Because cell towers don’t always send all types of signals though, your data signal might be different from your voice signal.

If you have an iPhone, there has been a way to get signal measurements in the past but the folks at Apple keep messing with it and it doesn’t always work. You’re better off finding a pal with an Android.

An even better way is to use a cellular signal meter. I admit this is a pretty hefty purchase if you’re going to use it just the one time, but it’s what the professionals use when they need to know how cell boosters work in commercial environments.

What if there isn’t enough signal?

If your phone or the meter you bought shows less than -100dBm (for example, -115) then that booster might not work well for you. It might only work in one room and not the whole house, or it might not work at all. Commercial installers might choose not to put in a booster system at all.

You can try putting in a system and using the highest gain cellular antenna. This one can give you ten times the signal of your cell phone. It’s highly directional and will need to be aimed toward a cell tower to work.

You can also try putting the antenna up high, past trees and other obstructions. This can double or triple the amount of signal you get.

Another option is calling a professional out to do a site survey to see what your options are. If you would like a consultation on a professional installation, give Solid Signal a call at 888-233-7563 and we’ll be happy to help you, answer all the questions you have, and hopefully recommend a professional in your area.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 8,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.