dBm (decibel-milliwatts) is a logarithmic unit used to express signal power. For Wi-Fi, it's always a negative number — the closer to zero, the stronger the signal. Minus 50 dBm is a much stronger signal than minus 80 dBm.

What's a good Wi-Fi signal strength?

Roughly -50 dBm or stronger is considered excellent, and -60 dBm or stronger is generally good enough for smooth video calls and streaming. Below about -70 dBm, expect slower speeds and more dropped connections; below -80 dBm, a connection is often unreliable.

Why does my Wi-Fi app sometimes show a stale reading?

Android limits how often an app running in the foreground can scan for nearby networks — four scans per two-minute window since Android 9. A rapid re-scan within that window can return the previous cached result instead of a brand-new one.

Does a strong dBm reading guarantee fast internet?

No. Signal strength measures how well your device can hear the router, not your internet speed. A strong signal to a slow or congested connection, or to an ISP with limited bandwidth, can still be slow.

NetworkingGuide

Wi-Fi Signal Strength (dBm) Explained

4 min readUpdated 2026-10-06

Short answer: Wi-Fi signal strength is usually reported in dBm, a negative number where closer to zero means stronger. As a rough, approximate guide: around -30 to -50 dBm is excellent, -50 to -60 dBm is good, -60 to -70 dBm is fair, -70 to -80 dBm is weak, and below -80 to -90 dBm is often unusable.

The dBm Scale (Approximate)

dBm range	Quality	What to expect
-30 to -50	Excellent	Maximum speed, very stable
-50 to -60	Good	Reliable for video calls and streaming
-60 to -70	Fair	Usable, but speed may dip under load
-70 to -80	Weak	Slower, more dropped packets
-80 to -90	Very weak / unusable	Frequent disconnects, often unusable

These are common industry rules of thumb rather than a universal standard — actual performance also depends on interference, the specific router and device, and how many other devices share the network.

Why Your Reading Might Look "Stuck"

If you're checking signal strength through an app, be aware of a platform-level limit: Android throttles how often an app in the foreground can scan for nearby Wi-Fi networks to four scans per two-minute window, a restriction in place since Android 9 (see Google's Wi-Fi scanning overview). Rapidly tapping "re-scan" within that window can return a cached result rather than triggering a fresh scan.

Checking Your Own Network

Our WiFi Manager app (Android) shows your current connection's signal strength alongside its security type, and scans for nearby networks and devices on your own network. If your signal looks weak, see how to fix common Wi-Fi connection problems for practical steps.