How to check your phone's real signal strength in dBm

Four bars and pages still won't load? Bars are a rough summary that every phone maker draws differently. The real measurement is signal strength in dBm, and both iPhone and Android can show it.

What dBm means

Signal strength is measured in decibel-milliwatts (dBm). The numbers are negative, and closer to zero is stronger: −70 dBm is a far better signal than −110 dBm. On 4G and 5G the value to look at is usually RSRP, the strength of the reference signal from the tower.

What the numbers mean (4G/5G RSRP)

• −80 dBm or higher: excellent.
• −80 to −90 dBm: good.
• −90 to −100 dBm: fair. Calls are fine; data may slow down.
• −100 to −110 dBm: poor. Expect dropouts.
• Below −110 dBm: very weak, close to losing service.

These ranges are a common rule of thumb. Speed also depends on signal quality and on how busy the tower is, not only on strength.

How to see it on Android

Open Settings › About phone › Status (sometimes called SIM status) and look for Signal strength. The path varies by manufacturer; searching Settings for “signal strength” usually finds it.

How to see it on iPhone

Check a reading: signal strength (dBm) checker

iPhone has a hidden Field Test Mode. Open the Phone app, dial *3001#12345# and tap call. On recent iOS versions, open the LTE or NR (5G) section and look for RSRP. The menus differ between iOS versions and carriers, and some carriers hide them.

Why your signal is weak, and what helps

• Distance and direction. The farther the tower, the weaker the signal. Knowing which side of the building it's on tells you where to sit.
• Walls and windows. Concrete, basements and metal-coated glass block signal. Try near a window or on a higher floor.
• Busy towers. In the evening or in a crowd, a strong signal can still be slow.
• Wi-Fi Calling. If your carrier supports it, calls can go over your home internet instead.

Find the nearest towers and test real speed

Cell Tower Locator shows the cell towers around you on a map and runs a speed test for download, upload and latency, so you can see where your signal comes from and which spot at home really gets the best connection.

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