dBm shows up in WiFi analyzer apps, router admin pages, and network tools, usually as a negative number like “-58 dBm.” It looks cryptic, but once you know the scale, it's the single most useful number for understanding why WiFi feels weak in a specific spot.
- The closer the number is to zero, the stronger the signal — “-50” is stronger than “-80.”
- RSSI and dBm are, in everyday use, the same thing.
- Real-time uses like gaming and video calls need a stronger signal than simple browsing does.
WiFi signal strength chart
| dBm range | Rating | What it means |
|---|---|---|
| -30 to -50 dBm | Excellent | Maximum speed, right next to the router |
| -50 to -60 dBm | Good | Reliable for most everyday use |
| -60 to -67 dBm | Fair | Fine for browsing; borderline for HD video and gaming |
| -67 to -70 dBm | Weak | Streaming and video calls may start to stutter |
| -70 to -80 dBm | Poor | Frequent buffering, drops likely |
| Below -80 dBm | Unusable | Connection may barely hold or drop entirely |
What is dBm?
dBm (decibel-milliwatts) is the standard unit for measuring WiFi signal power. It's a logarithmic scale, which is why the numbers are negative and look confusing at first: -30 dBm is a very strong signal, while -90 dBm is barely usable. The closer the number is to zero, the stronger the signal — so “higher” actually means less negative, not a bigger number in the everyday sense.
Is RSSI the same as dBm?
Not exactly, but in everyday use they're treated as interchangeable. RSSI (Received Signal Strength Indicator) is the general concept of “how strong is the signal I'm receiving,” and it's almost always reported using the dBm scale. So when an app shows you an RSSI value, it's normally showing you a dBm number.
WiFi signal strength chart: what's a good dBm?
The table above is a reasonable general guide, but the honest answer is “it depends on what you're doing.” A signal that's perfectly fine for checking email can be too weak for a video call happening at the same time, in the same spot.
What dBm do you need for gaming, streaming, or video calls?
Real-time uses are pickier than they look on paper — a signal that shows full bars can still cause lag if it's below about -67 dBm. As a rule of thumb, try to keep gaming and video calls above -65 dBm, and treat -70 dBm as the point where problems become noticeable, not -80 dBm as some looser guides suggest.
Why is dBm always a negative number?
dBm measures power relative to 1 milliwatt on a logarithmic scale, and a WiFi signal that reaches a device — after traveling through air and walls — is always weaker than that reference point. That's why the result is expressed as a negative number. It isn't a sign that something's wrong; every WiFi signal you'll ever measure will be negative.
How to check your WiFi's dBm
Most phones don't show dBm by default — the signal-bars icon in the status bar doesn't reveal the actual number, and different phones can show the same number of bars at quite different real signal strengths. Perfect WiFi shows the exact dBm reading at any point in your home, and lets you place that measurement directly on your floor plan to see exactly where the signal drops below a usable level.
FAQ
Does a higher dBm number mean a stronger signal?
Yes, but “higher” here means closer to zero. -50 dBm is a stronger signal than -80 dBm, even though -80 looks like the “bigger” number.
What dBm is good enough for online gaming?
Aim for -65 dBm or better. Below -70 dBm, lag and packet loss become noticeably more likely, even if other apps still feel fine.
Why is my WiFi dBm always negative?
Because dBm measures signal power relative to 1 milliwatt on a logarithmic scale, and a WiFi signal that reaches your device is always weaker than that reference — so it's always shown as negative.
Is RSSI the same thing as dBm?
In practice, yes. RSSI is the general term for signal strength, and it's almost always reported as a dBm value.
How can I check the dBm value in a specific room?
Your phone's signal-bars icon won't show it. You need a WiFi analyzer or network tool — Perfect WiFi shows the exact dBm reading and lets you record it at specific spots on your floor plan.
Want to see the real dBm number in every room, not just a bars icon? Perfect WiFi measures it and puts it on your floor plan.
Check your WiFi signal in Perfect WiFi