How to Read Signal Strength Indicators

Understanding signal strength indicators helps you optimize your mobile connectivity. From the simple bars on your phone to technical measurements like dBm, this guide explains how to interpret signal strength and use it to improve your connection.

Understanding Signal Bars

The signal bars on your phone provide a quick visual indicator of signal strength:

• Full bars (4-5 bars): Excellent signal, optimal performance
• 3 bars: Good signal, reliable service
• 2 bars: Fair signal, may experience occasional issues
• 1 bar: Weak signal, likely to have connectivity problems
• No bars: No signal, no service

Important: Signal bars are relative and can vary between devices and carriers. They provide a general indication but not precise measurements.

dBm: The Technical Measurement

dBm (decibels relative to milliwatt) is the technical measurement of signal strength:

• Measured in negative values (e.g., -70 dBm)
• Closer to zero = stronger signal
• More negative = weaker signal
• Provides precise, comparable measurements

Signal Strength Reference Table

Signal Strength	dBm Range	Quality	Performance
Excellent	-50 to -70 dBm	5 bars	Optimal speeds, no issues
Good	-70 to -85 dBm	3-4 bars	Reliable service, good speeds
Fair	-85 to -100 dBm	2 bars	Service may be slow or intermittent
Poor	-100 to -110 dBm	1 bar	Frequent disconnections, very slow
No Signal	Below -110 dBm	No bars	No service available

Accessing Signal Strength on Your Device

iPhone (Field Test Mode)

To see dBm values on iPhone:

1. Dial *3001#12345#* and press call
2. Field Test Mode opens
3. Navigate to "Serving Cell Info" or "LTE"
4. Look for "rsrp" (Reference Signal Received Power) for 4G/5G
5. For 3G, look for "RSCP" (Received Signal Code Power)

To keep dBm visible on status bar: Hold power button, when "slide to power off" appears, hold home button until Field Test closes. The signal bars will now show numbers.

Android

To see signal strength on Android:

1. Go to Settings > About Phone
2. Tap "Status" or "SIM Status"
3. Look for "Signal Strength"
4. Values shown in dBm or ASU (Arbitrary Strength Unit)

Some Android devices also support: Settings > About Phone > Status > Signal Strength

Understanding Different Network Types

4G/LTE Signal Measurements

• RSRP (Reference Signal Received Power): Primary measurement for LTE
• RSSI (Received Signal Strength Indicator): Overall signal strength
• SINR (Signal to Interference plus Noise Ratio): Signal quality indicator

5G Signal Measurements

• SS-RSRP: 5G equivalent of RSRP
• SS-RSRQ: Signal quality measurement
• SS-SINR: Signal-to-noise ratio for 5G

Factors Affecting Signal Strength

Signal strength varies based on:

• Distance from tower: Closer = stronger signal
• Obstacles: Buildings, trees, terrain block signals
• Network congestion: Too many users can degrade signal quality
• Weather: Severe weather can affect signals
• Device quality: Better antennas receive stronger signals

Using Signal Finder to Understand Strength

Signal Finder helps you understand signal strength by:

• Showing distance to nearest towers (closer = stronger signal typically)
• Displaying real-time signal strength indicators
• Comparing signal strength from different carriers
• Identifying optimal locations for best signal

Improving Signal Strength

Based on signal strength readings:

• If below -85 dBm: Move closer to window or higher elevation
• If below -100 dBm: Consider moving location or using signal booster
• If consistently poor: May need to switch carriers or use Wi-Fi calling

Signal Strength vs. Data Speed

Important distinction:

• Signal strength: How strong the connection is
• Data speed: How fast data transfers
• Strong signal doesn't always mean fast speeds (network congestion affects speed)
• Weak signal almost always means slow speeds

Monitoring Signal Over Time

Track signal strength to identify patterns:

• Note signal strength at different times of day
• Compare signal in different locations
• Identify areas with consistently good or poor signal
• Use Signal Finder to map signal strength patterns

Conclusion

Understanding signal strength indicators—from simple bars to technical dBm measurements—helps you optimize your mobile connectivity. Use Signal Finder to identify tower locations and find areas with the strongest signals. By monitoring signal strength and understanding what the measurements mean, you can make informed decisions about positioning, carrier selection, and connectivity optimization.