Why a number is more useful than bars
Signal bars are a simplified visual chosen by the phone and carrier. A numerical reading is more useful when you compare the same iPhone in different rooms, locations and times.
RSRP and RSSI are different measurements
RSRP describes LTE or 5G reference-signal power. RSSI is a broader received-power measurement. Select the correct metric because the practical ranges are not interchangeable.
What signal strength cannot explain
Strong received power can still produce slow data when interference, congestion, limited spectrum or backhaul is the real constraint. Pair the reading with a speed test and local tower context.
Frequently asked questions
Is a dBm value closer to zero better?
For received power, a value closer to zero is generally stronger. For example, -80 dBm is stronger than -105 dBm.
Is -100 dBm a good iPhone signal?
For RSRP, around -100 dBm is generally fair and usable, but signal quality and network load can still change performance.
Can this webpage read my iPhone signal automatically?
No. Safari does not expose reliable cellular radio measurements to webpages. Enter a reading you obtained from the device or another trusted source.