Wireless signal strength is measured in dBm (decibel milliwatts) and is, somewhat confusingly, expressed only as negative values.
So what should we consider a good, acceptable, or poor Wi-Fi signal strength?
|Signal Strength||Expected Quality||Required For|
|-30 dBm||Maximum signal strength, you are probably standing right next to the access point.|
|-50 dBm||Anything down to this level can be considered excellent signal strength.|
|-60 dBm||Good, reliable signal strength.|
|-67 dBm||Reliable signal strength.||The minimum for any service depending on a reliable connection and signal strength, such as voice over Wi-Fi and non-HD video streaming.|
|-70 dBm||Not a strong signal.||Light browsing and email.|
|-80 dBm||Unreliable signal strength, will not suffice for most services.||Connecting to the network.|
|-90 dBm||The chances of even connecting are very low at this level.|
You can use a Wi-Fi scanner application to measure the received signal strength at a specific location and time. The number you are looking for is the RSSI, which means Received Signal Strength Indicator.
If you are on a computer running Mac OS X, you can also get the RSSI without installing any additional applications:
If what you are actually trying to do is map the signal strength for an entire house or apartment, we recommend using a heatmapping tool rather than a Wi-Fi scanner. This tool will help you visualize the wireless coverage in different parts of your home.
If you have measured the received signal strength at a particular spot and deemed it to be too weak, there are a few things you can do, and some things you absolutely should not do.
First of all: Do not try to boost the signal strength sent from your access point, by replacing the antenna, building your own antenna booster or similar. You risk worsening your coverage further, tripping up your neighbors, and in some cases even breaking the law.
A number of factors influence the signal strength you receive, but single most important thing you can do for your wireless coverage without adding or replacing equipment is not hiding your access point(s) away.
You can read more about this in Stop Clearing Away Your Wi-Fi Signal.
For more information about what materials and obstacles are worst for Wi-Fi signals, see How Much Wi-Fi Signal Loss Is Caused By Building Materials.
Article by Jan Pedro Tumusok and Jorunn D. Newth