What the signal bars on your smartphone really mean

Many people use the signal bars on their smartphone to judge connectivity, but they are not standard measurements of signal strength.

In fact, the way these bars reflect mobile signal varies greatly between devices, as each manufacturer uses a different algorithm. It can also vary between devices from the same manufacturer.

All you can see is your device displaying signal strength on a scale of several “bars”, where four bars indicates a stronger signal than three bars, for example.

Samsung explains how it works

Samsung explained to MyBroadband that the signal bars on its Galaxy devices measure signal strength using RSCP, which is given in dBm.

Signal strength and signal quality are both measured in decibels (dBm), which is expressed as a negative number.

Decibel values closer to 0 represent a stronger signal, and a signal strength beyond -98 dBm is considered poor.

Signal quality refers to the signal-to-noise ratio, with values closer to 0 being better.

Signal quality between -10dBm and 0dBm is considered good, while values beyond -10dBm are considered poor.

Samsung provided MyBroadband with a detailed explanation of what RSCP value each signal indicator state refers to.

The table below details the RSCP value indicated for each signal bar illuminated on the device, depending on which network it is connected to.

Network 0 signal bars 1 signal bar 2 signal bars 3 signal bars 4 signal bars
2G < -102dBm >= -102dBm >= -98dBm >= -94dBm >= -87dBm
3G < -110dBm >= -110dBm >= -104dBm >= -98dBm >= -90dBm
4G (LTE) < -117dBm >= -117dBm >= -110dBm >= -100dBm >= -90dBm

No common standard

While the measurements above are accurate for Samsung’s Galaxy smartphones, these values are not applicable to other mobile brands or even other Samsung models – as there is no common standard for signal indicators.

This means that two different smartphones placed in an area with equal signal strength could display different readings on their signal indicators.

Additionally, signal indicator values may vary according to mobile operators, making it impossible to read objective signal data from your smartphone’s signal bars.

While more illuminated signal bars generally means better signal, you will not be able to tell how good your signal is in terms of dBm.

Measuring your real signal

While signal bars are not an effective tool for measuring signal strength, there are standardised measurements which can be used for accurate readings.

Users can accurately test by putting their device in field test mode.

If you have an Apple device, you can place your phone in field test mode by dialing *3001#12345#*.

Android users can view their signal strength in their Settings app and can download a field test app for more information.

Field test mode will display your accurate signal strength and quality readings in dBm.

Now read: We have South Africa’s best cellular network – Vodacom

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What the signal bars on your smartphone really mean