Cellular Signal Strength: How to Test It and What It Means
Bars Do Not Reflect Signal Strength
When calls start dropping or your data slows to a crawl, it's natural to glance at your phone's signal bars for an answer. However, those bars are not a precise measurement of cellular signal strength. The same signal may appear differently depending on your phone model, carrier, or operating system. Thankfully, far more accurate ways to test your signal strength exist.
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How to Test Cellular Signal Strength on Your Phone
Cell phone signal strength is measured in dBm (decibel-milliwatts). You may find many articles claiming signal strength is measured in dB (decibels), but that's not entirely accurate. While dB and dBm are related, there is an important distinction:
- dB is a relative measurement indicating change (gain or loss) in signal strength without specifying an exact signal strength value.
- dBm is an absolute measurement, representing power level relative to 1 milliwatt, providing an exact signal strength measurement.
By finding your dBm reading, you can identify your true 5G and 4G LTE signal strength in your specific location. Unlike signal bars, the measurement does not vary based on your device manufacturer or model.
A Quick Note on RSRP/RSSI/RSRQ: You may also see RSSI (total signal power plus noise and interference), RSRP (signal strength), and RSRQ (signal quality) while testing. All are cellular signal measurements. RSRP is the measurement to focus on when testing cellular signal strength. We explain these measurements in more detail in the FAQs below.
There are two main ways to measure cellular signal strength:
- Field Test Mode: A built-in diagnostic tool on most smartphones.
- Signal Strength Checker Apps: Downloadable tools that display your real-time signal strength and related network data.
The process and app options differ slightly between Android and iPhone devices. Let's break it down.
How to Check Signal Strength on Android
Measuring cell signal strength on Android devices is very simple and can be done with just a few taps.
Field Test Mode for Android
The exact path varies by phone model and OS version, but generally, here's how to do it:
- Turn off your WiFi connection.
- Go to Settings
- Tap About Phone
- Tap Status Information or Network
- Tap SIM Card Status
- Look for Signal Strength - your dBm reading will be listed there.
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Recommended Android Signal Strength Apps
Alternatively, you can use a signal strength app to measure the strength of your phone's service signal. The Play Store offers a ton of options. These are our top two favorites:
- Network Cell Info Lite: Features an easy-to-read signal measurement gauge that quickly updates as you move location. It also displays network details, such as connected band, RSRQ, RSSNR, and more.
- weBoost App: Simplest signal testing tool available, designed by a leading cell phone signal booster manufacturer. Measuring signal performance is as easy as tapping a button. Results are displayed on a color-coded gauge.
How to Check Signal Strength on iPhone
On iPhones, measuring cell signal strength is a little trickier and only possible via Field Test Mode. However, it's important to note that while every iPhone can access Field Test Mode, not every model and iOS version will display dBm values due to chipset and carrier limitations.
Field Test Mode for iPhone
Finding your dBm through Field Test Mode on iPhones varies across iOS versions, and it doesn't help that Apple constantly changes the layout of its Field Test Mode screen. In general:
- Turn off your WiFi connection.
- Open your Phone app.
- Dial *3001#12345#* and hit call.
- Field Test Mode (FTM) Dashboard will open.
- Look for RSRP (Reference Signal Received Power) values - this is your cellular signal strength in dBm.
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For iPhone Field Test Mode instructions by iOS version, see our Field Test Mode guide.
Note: If your iPhone doesn't show dBm readings, your next-best option is a speed test app to help you find strong signal areas.
Useful iPhone Signal Strength Apps
Unfortunately, the Apple App Store does not offer true cellular signal strength measurement apps. However, here are our top app recommendations that can help make checking your signal strength easier:
- weBoost App: Provides iPhone users with step-by-step Field Test Mode instructions and helps visualize signal reliability.
- Open Signal: While it doesn't show dBm values, it offers detailed speed tests to identify your best signal spots.
What Is a Good dBm for Cell Phones?
Cell signal strength typically ranges from -50 dBm to -120 dBm. Generally, a good RSRP or dBm reading is anything above -95 dBm. You'll notice dropped calls, failed texts, and slow data the closer you get to -120 dBm.
Here is an estimated dBm signal strength breakdown (and their possible bar assignments, depending on carrier/phone manufacturer):
|
Signal Strength (dBm) |
General Quality |
Typical Bars |
Experience |
|
-50 to -80 dBm |
Excellent |
5 Bars |
Fast data, uninterrupted calls |
|
-80 to -100 dBm |
Good |
3-4 Bars |
Stable connection |
|
-100 to -110 dBm |
Fair |
2-3 Bars |
Occasional slowdowns |
|
-110 to -120 dBm |
Poor |
1-2 Bars |
Dropped calls, slow data |
|
-120+ dBm |
Very Poor |
0-1 Bar |
Unusable connection |
How to Increase Mobile Signal Strength
If you're experiencing poor signal strength, then it's likely the result of cell tower distance, signal-blocking building materials, or physical obstructions. For a complete list, visit our guide on why your service is bad.
Cell phone signal boosters are designed to improve your connection and coverage. These devices capture your existing outside signal, amplify it, and rebroadcast it indoors. For more information, check out our article on How Cell Phone Boosters Work.
Once installed, a booster can improve your dBm reading, resulting in better voice quality, fewer dropped calls, faster data speeds, and longer battery life.
What Does That Improvement Look Like in Practice?
Below is a real-world before-and-after dBm result from a weBoost cell phone booster installation. Because stronger dBm readings are closer to zero, the change shows exactly how much the booster improved cellular signal inside the building.
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*Major dBm improvement post weBoost Installed Home Complete installation in a Rural East Texas home.
Our Top Signal Booster Picks
If your dBm readings confirmed that weak cellular signal is affecting your home or business, a cell phone signal booster can help. Here are three options designed for different coverage needs and budgets:
Budget-friendly option for small homes or spot coverage for multiple carriers.
Shop Now: $379.99
Professional installation included. Great for whole-home coverage up to 7,500 sq. ft.
Shop Now: $1,499.99
Our most powerful single-carrier booster for homes and offices. Offers 100dB of gain across 4G, 5G, and LTE signals for up to 15,000 sq. ft
Shop Now: Starting at $1,298Not sure which system fits your space? Explore our complete cell phone signal booster guide to compare more options.
Already have a booster and need help setting it up? Follow our Simple Cell Phone Signal Booster Installation Guide, or contact our team by phone (1-800-470-6777) or email (sales@signalboosters.com) for personalized assistance.
FAQS
Once you've figured out how to measure your signal strength, here's how to put that information to work:
- Walk around your home or property with your phone's Field Test Mode or app open.
- Identify areas with the highest (closest to -50 dBm) and lowest signal readings.
- Note where your signal strength drops - these are your weak spots or dead zones.
- You can use this info to choose the best spot for calls and data use, pinpoint the ideal placement for a cell signal booster's outdoor antenna, and determine if a booster system could help improve your coverage.
Signal strength is how much signal your phone or other device is receiving. Signal quality is how much noise or interference that signal is contending with.
Radio signals are all around us from other cell towers, other calls, other devices, or even appliances. These signals can interfere with your cell phone connection to the tower. The more interference or noise there is, the lower your signal quality will be.
It is possible to have bad signal quality and good signal strength or bad strength and good quality. Ideally, the two need to be good for clear calls and data. If you have good signal strength, but terrible quality, you will still experience dropped calls, slow data speeds, and breaks in voice.
RSRP and RSSI are two measurements you may encounter when checking cellular signal strength.
RSRP, or Reference Signal Received Power, measures the strength of specific reference signals from an LTE or 5G cell tower. It is generally the more useful measurement for evaluating cellular signal strength. RSRP is shown in dBm, with values closer to zero indicating a stronger signal.
RSSI, or Received Signal Strength Indicator, measures the total received power across a channel. This can include the desired cellular signal as well as interference and background noise. RSSI is commonly associated with older network technologies and provides a broader, less precise picture than RSRP.
Your phone may display one or both measurements depending on its model, operating system, carrier, and current network connection.
Field Test Mode and most signal-strength apps measure the carrier network connected to your phone's SIM or eSIM. To get a live signal reading for another carrier, you need a SIM, eSIM, or device connected to that network.
Some apps provide estimated coverage maps for multiple carriers. These can suggest which carrier may offer the strongest coverage in your area, but they are estimates rather than live measurements taken from your exact location.
You can check WiFi signal strength through your phone or computer's network settings or use a WiFi analyzer app for a more detailed reading. Keep in mind that this article focuses on cellular signal strength, which is separate from how to check wifi signal strength.
Start by testing your signal in several locations to identify where it is strongest and what may be interfering with it. If weak outdoor signal or signal-blocking building materials are affecting indoor coverage, a cell phone signal booster may help. See the How to Increase Mobile Signal Strength section above for more information.
Contact Us to Boost Your Signal Strength
Your dBm readings give you a clearer picture of your cellular signal and what to do next. If you confirmed weak signal and need help choosing a booster, or you already own a system and want guidance on installation or performance, our team can help. Contact us by phone at 1-800-470-6777, email us at sales@signalboosters.com, or reach out through live chat for personalized support based on your readings, location, and coverage goals.
