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What is dBm? How Does it Affect Your Cell Signal Strength?

Written by Alejandra Jasso
21st Feb 2024

dBm Meaning and Significance

Ever wondered how to get the best measurement of your cell phone’s signal strength?

While signal bars can help give you a general idea of how strong your signal might be at any given location, they are subjective. It all depends on the algorithm your carrier or phone uses to represent decibels as cell phone bars. The true measure is in decibel-milliwatts, or dBm for short.

To more accurately gauge signal strength — say, for the optimal placement of a cell signal booster — the key is to better understand decibel-milliwatts.

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What is dBm?

The decibel (dB) is a relative scale used to represent the increase or decrease of signal strength. Because the decibel is logarithmic and therefore a dimensionless unit, we apply the unit dBm as an absolute point of reference.

This means that signal strength is measured in reference to one milliwatt, and can be calculated as ten times the log of the signal strength in milliwatts. Unit is expressed as a negative number. The dB simply quantifies the ratio between two values, and those values are measured by dBm. So once the dBm has been established, only then can you measure any change in decibels (dB).


Its capability to express values both large and small in short form makes dBm the measurement of choice in radio, microwave, and fiber optic networks. In the world of cellular signal boosters, dBm measurements represent the strength of a signal at any given location, as well as the amount of power an antenna is capable of amplifying.

What is a Good dBm for Signal?

Typically, cellular signal strength ranges from -50 dBm to -120 dBm.

The closer you are to 0 the better. On average, though, a strong outside signal clocks in somewhere around -50 to -70 dBm. Good signal strength ranges between -80 to -90 dBm. Anything below -100 dBm is considered poor signal strength.

The use of a cell phone signal booster can improve your existing dBm exponentially. According to the logarithm, the signal strength doubles with every third decibel, meaning that a dBm signal strength of something like -70 is actually twice the power of -73 dBm. The numbers may not make it look like a great change has occurred, but in reality, the decibels have grown exponentially.

How Do I Take dBm Measurements on My Phone?

When the strength of your cell phone signal matters most, skip the bars on your screen and opt for the master precision of dBm signal strength measurements.

Whether it’s choosing the strength of your signal booster or figuring out where to install it for optimal efficiency, apps like Network Cell Info make it easy to monitor and measure signal strength in real time. For more app options, visit Best Apps to Find Mobile Signal Strength.

Signal strength measurements can also be attained natively. Android phones offer a decibel-reading function in their settings, while some iPhones can access decibel information via field test mode. Simply “call” the number *3001#12345#* from the keypad and look for rsrp results to identify signal strength results. For step-by-step instructions, visit How to Test Cell Phone Signal Strength.

An accurate reading of your dBm signal strength will not only optimize the performance of your cell phone booster antennas and amplifiers, but you’ll also sound like a true tech wizard the next time your friends are flailing their phones around in search of those elusive bars.

What Can I Do If I Have Almost No dBm?

Our #1 recommendation to improve your dBm is a cell phone signal booster. In a perfect world a unit boasting up to 65 dB gain, could convert a -110 dBm signal to -45 dBm. Realistically, there are many factors that affect actual performance. In any case, they can significantly transform connectivity in your home, office, or vehicle.

For alternative recommendations, check our guide on Ways to Boost Cell Phone Signal.

Contact Us Today!

Wilson Amplifiers is the leading provider of signal boosters. Cell phone boosters amplify 5G, 4G, and LTE for any phone with any carrier for home, office, or vehicle.

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