Signal strength (dBm) checker
Enter the RSRP value your phone shows to see how strong your 4G or 5G signal really is. Bars are a rough summary that every phone maker draws differently; dBm is the actual measurement.
−95 dBm · Fair
Calls are fine; data can slow down, especially indoors or at busy times.
Convert ASU to dBm (Android)
Some Android phones show signal in ASU instead of dBm. Pick the network type and enter the ASU number.
4G and 5G signal strength chart (RSRP)
| RSRP | Rating | What it means |
|---|---|---|
| −80 dBm or higher | Excellent | Strong signal. Calls, video and fast downloads should all work, unless the tower is busy. |
| −80 to −90 dBm | Good | Reliable for calls, streaming and most downloads. |
| −90 to −100 dBm | Fair | Calls are fine; data can slow down, especially indoors or at busy times. |
| −100 to −110 dBm | Poor | Expect dropped calls and slow or patchy data. |
| below −110 dBm | Very weak | Close to losing service. Try a window, a higher floor or Wi-Fi Calling. |
How to find your reading
iPhone
- Open the Phone app, dial *3001#12345# and tap call to open Field Test Mode.
- On recent iOS versions, open the LTE or NR (5G) section.
- Look for RSRP. Menus differ by iOS version and carrier, and some carriers hide them.
Android
- Open Settings › About phone › Status (sometimes called SIM status).
- Look for Signal strength, shown in dBm and ASU.
- If you can't find it, search Settings for “signal strength”.
Why the number is negative
dBm compares the received power with one milliwatt. A phone receives a tiny fraction of that, so the values are negative: the closer to zero, the stronger. Every 10 dB is a factor of ten, so −80 dBm is ten times stronger than −90 dBm, and a hundred times stronger than −100 dBm.
RSRP, RSSI, RSRQ and SINR
On 4G and 5G, RSRP measures the strength of the tower's reference signal, which is why it is the best single number for coverage. RSSI is the total power the phone receives, including noise and other cells, so it reads higher and isn't comparable with RSRP. That's also why this checker only rates RSRP; 2G and 3G readings use different scales.
Strength isn't everything. RSRQ and SINR describe signal quality: how much of what you receive is useful signal rather than interference. A strong RSRP with poor SINR, common near crowded towers, can still be slow.
How to get a better signal
- Move towards a window, especially one facing the nearest tower.
- Go up a floor; basements and ground floors in dense areas are the weakest spots.
- Thick concrete and metal-coated glass block signal; try another room.
- Turn on Wi-Fi Calling if your carrier supports it.
- Try switching between 5G and 4G; a weaker 5G cell can be slower than a solid 4G one.
- Skip signal-booster stickers and apps that claim to strengthen reception; they can't.
How to check your phone's real signal strength in dBm
Frequently asked questions
Is −100 dBm good?
On 4G or 5G, an RSRP of −100 dBm is at the line between fair and poor. Calls usually work, but data can be slow and calls may drop indoors. Moving to a window or a higher floor often helps.
What is a good RSRP?
As a rule of thumb, −80 dBm or higher is excellent and −80 to −90 dBm is good. Between −90 and −100 dBm is fair, and below −100 dBm you can expect problems. Operators and devices differ, so treat these as guides.
How do I convert ASU to dBm?
It depends on the network. For 4G and 5G, dBm is about ASU minus 140. For 3G, RSCP is ASU minus 120. For 2G, dBm is twice the ASU minus 113. The converter on this page does it for you.
Why do two phones show different dBm in the same place?
Phones have different antennas and cases, may be connected to different towers or frequency bands, and report different measurements. Compare readings from the same phone in different spots instead.
Is −70 dBm good?
On 4G or 5G, an RSRP of −70 dBm is excellent. If your connection is still slow with a reading like that, the tower may be busy or signal quality (SINR) may be poor.
Does a better dBm mean faster internet?
Usually, but not always. Speed also depends on signal quality, how many people share the tower, your plan and the network's capacity. Run a speed test to see what you actually get.