Unstable connections, slow page loading speeds, and constant video stream interruptions are familiar symptoms for many home network users. Often, the cause lies not with the ISP, but with insufficient signal strength, which can't penetrate obstacles like walls or household appliances. Understanding how to measure this parameter is the first step to creating a stable and fast wireless network in any room.
Unlike simply seeing "sticks" on a smartphone screen, professional diagnostics require working with precise numerical values. dBm (decibels per milliwatt) is a unit of measurement that indicates the actual strength of a radio signal. The closer the value is to zero, the stronger the signal, but in reality, we always deal with negative numbers, where a lower absolute value indicates better connection quality.
To conduct a proper diagnosis, you need to arm yourself with the right tools and know which indicators to look for in the operating system interface or a specialized application. In this article, we'll examine testing methods for various devices, explain the physics behind the process, and help you interpret the data to improve the quality of your Wi-Fi connections.
⚠️ Note: Router settings interfaces and mobile apps may differ depending on the firmware version or device model. If you don't see the described options, consult the official documentation from your equipment manufacturer.
Understanding units of measurement and signal levels
Before we begin measuring, it's important to understand the scale by which we'll be assessing connection quality. Wi-Fi signal strength is measured in dBm, and it's a logarithmic scale. This means that even a few unit changes can significantly impact connection stability and data transfer speed.
The values are always negative, as they represent the ratio of signal strength to a reference level of 1 milliwatt. A signal strength of 0 dBm is theoretically ideal, but unachievable in practice. Actual values range from -30 dBm (in the same room as the router) to -90 dBm (the edge of the coverage area).
Why are the values negative?
Negative dBm values mean that the signal power is less than the reference level of 1 mW. The logarithm of a number less than one is always negative. For example, -50 dBm is better than -80 dBm, since -50 is closer to zero.
There's a generally accepted gradation of signal levels that helps you quickly assess network status. Below is a table to help you interpret the values you receive.
| Range (dBm) | Signal quality | Description |
|---|---|---|
| -30... -50 | Excellent | Ideal for 4K video streaming and online gaming |
| -51... -65 | Good | Stable operation of most applications |
| -66... -75 | Average | There may be speed issues, the video is buffering |
| -76... -85 | Bad | Unstable connection, possible interruptions |
| -86... -90 | Critical | The connection is almost impossible or extremely slow |
Understanding these ranges will allow you to objectively assess whether you need to relocate your router or purchase an extender. Don't rely solely on subjective speed measurements when you can rely on precise data.
Checking signal strength on Windows
The Windows operating system provides built-in tools for basic diagnostics, but to obtain accurate power data in dBm, you'll need to use the command line. This is the fastest way to obtain information without installing third-party software.
Open the command prompt by typing cmd in the Start menu search and run it as administrator. To get a detailed report on your current wireless connection, use the command:
netsh wlan show interfacesIn the list that appears, find the line Signal (Signal), where the value will be expressed as a percentage. While percentages are convenient for quick assessment, they are less informative than dBm. You can use an approximate formula for conversion, but specialized utilities are better.
If you prefer a graphical interface, many Wi-Fi adapter drivers have their own tabs in Device Manager or Control Panel that display Link QualityHowever, it is the numerical values that should be trusted, not the color indication.
Diagnostics on Android and iOS
Mobile devices are the gadgets we carry around our homes, making them ideal for checking coverage in different rooms. Android offers significantly more diagnostic capabilities thanks to the open nature of the system.
Many Android smartphones have a hidden engineering menu. To access it, open the Phone app and enter the code ##4636##In the menu that opens, select “Wi-Fi information”, where in the “Connection info” section you will see the exact value RSSI (Received Signal Strength Indicator) in dBm.
iOS users are less fortunate: Apple hides this data in the standard interface. The only legal way to access Wi-Fi technical data on an iPhone is using a utility AirPort Utility from Apple. After installing the app, go to iOS Settings, find AirPort Utility, and turn on the "Wi-Fi Scanner" toggle.
Once the scanner is activated, launch the AirPort Utility app, click Scan Wi-Fi, and you'll see a list of networks with their actual strength readings. This is the only way to see the exact RSSI value on iPhone without jailbreak.
⚠️ Note: On some Android models, engineering menu codes may differ or be blocked by the manufacturer. In this case, use third-party apps from Google Play, such as WiFi Analyzer or Network Cell Info.
Using specialized PC programs
For a thorough analysis of the wireless environment on a computer, specialized analyzer programs are best suited. They not only display the current signal strength but also visualize the noise level in the air, which is critical for selecting a clear channel.
One of the most popular programs is Acrylic Wi-Fi Home or inSSIDerThese utilities generate graphs showing how signal strength changes over time. This allows you to identify interference that might not be visible in a single measurement.
When using such programs, pay attention to the differences between signals from neighboring networks. If your router operates on the same frequency as a powerful neighbor's network, you will experience interference even if your signal strength is strong.
What to check in a Wi-Fi analyzer
An important parameter in such programs is SNR (Signal-to-Noise Ratio) is the signal-to-noise ratio. A high signal level with a high noise level will result in low speed. Optimally, the difference between the signal and noise is more than 20-25 dB.
Analysis via the router's web interface
The most reliable source of connection status information is the router itself. By accessing its web interface, you can see how the router "sees" connected devices or check the connection status with your ISP (if it's a WAN connection).
To enter the settings you usually need to enter the IP address (often 192.168.0.1 or 192.168.1.1) in your browser. Look for sections titled "Status," "Wireless Statistics," or "Wireless Network Status."
Here you can find a list of connected clients (Client List) and the signal strength for each one. This is a unique, "other-side" view: you'll see how well the router can hear your phone or laptop, which isn't always symmetrical to how well the device can hear the router.
⚠️ Please note: Data in the web interface may be delayed. If you're moving around your apartment for testing, please refresh the status page manually to ensure the latest data.
Some modern systems such as Keenetic, Asus or MikroTik, have built-in real-time monitoring tools that display a signal strength (RSSI) graph for each active client directly in the connection list.
Factors Affecting Signal Strength
Understanding what weakens the signal will help you correctly interpret your measurements. Signal strength is not constant; it changes dynamically depending on a variety of environmental factors.
Physical obstacles are Wi-Fi's main enemy. Concrete walls with rebar, mirrors, aquariums, and even people (who are made of water) absorb and reflect radio waves. The 5 GHz band, which provides high speeds, penetrates walls much worse than 2.4 GHz.
Household appliances also contribute. Microwave ovens operating at 2.4 GHz can completely jam Wi-Fi while heating food. Cordless phones and Bluetooth devices also create interference in this frequency range.
Finishing materials matter: foil insulation behind wallpaper can turn a room into a "Faraday cage," completely blocking the signal. In such cases, measurements will show a sharp drop in power upon entering the room.
Frequently Asked Questions (FAQ)
Why is the internet speed low although the signal level is high (-40 dBm)?
A strong signal strength only guarantees a stable connection to the router, not internet speed. Low speeds can be caused by bandwidth congestion from neighbors, ISP restrictions, an overheating router, or issues with the server you're accessing.
Can a signal booster program really increase power?
No. Software "amplifiers" are a myth. Transmitter power is limited physically and legally. Such programs can only optimize OS settings or prioritize traffic, but they cannot increase the physical transmit power of the antenna.
What is the difference between RSSI and dBm?
dBm is an absolute unit of power measurement. RSSI (Received Signal Strength Indicator) is a relative index used by drivers. Although they are often equated, RSSI can scale differently depending on the chip manufacturer (for example, from 0 to 60 or from 0 to 255), whereas dBm is always tied to milliwatts.
Does the number of connected devices affect signal strength?
The number of devices does not reduce the physical signal strength of the router. However, it does divide the channel's bandwidth and increases the latency for data packets to be transmitted, which is subjectively perceived as a deterioration in connection and a decrease in speed.