The stability of a home or corporate internet connection directly depends on the quality of the radio channel, which is often perceived as something abstract. When videos start buffering, or online games freeze while loading, we first look for the culprit among providers or equipment, forgetting to check the physical connection. Understanding What is considered a good WiFi signal?, is the foundation for proper diagnosis and troubleshooting of communication problems.
Many users mistakenly believe that if a device shows network availability, the data transfer quality is fine. However, indicators on a smartphone or laptop screen often provide only an approximate, averaged estimate, concealing real issues with attenuation or interference. Accurate data can only be obtained through specialized utilities that display the power level in decibel-milliwatts (dBm).
In this article, we'll explore the technical nuances of measuring radio signal strength, learn to distinguish between the working range and the critical range, and examine factors that can turn fast internet into a painful wait. You'll learn why -50 dBm is better than -80 dBm, and how to correctly interpret these negative numbers to optimize your home network.
Units of measurement and physics of signal attenuation
Wireless connection quality is assessed using the logarithmic unit dBm, which expresses the ratio of signal strength to one milliwatt. A key feature of this scale is that all values are negative, as the received signal strength is always less than the reference milliwatt due to transmission losses. The closer the value is to zero, the stronger the signal, so -30 dBm is ideal, practically unachievable in everyday life, while -90 dBm means complete loss of connection.
The physics of radio wave propagation dictates its own strict rules: the signal attenuates exponentially with increasing distance and obstacles. Walls, ceilings, mirrors, and even aquariums act as filters, absorbing or reflecting some of the wave energy. Understanding this process is essential for proper placement. access points and routers, especially in apartment buildings or office buildings with complex layouts.
It's important to distinguish between dB (decibel) and dBm. While dBm is an absolute power value, dB indicates a relative change (gain or attenuation). For example, an antenna with a gain of 5 dB doesn't create energy from the air, but rather redistributes the radiation pattern, amplifying the signal in a specific direction at the expense of other areas. This is critical when selecting equipment for coverage enhancement.
⚠️ Attention: Don't confuse the router's transmitter power (usually up to 100 mW or 20 dBm) with the received signal strength. High transmitter power doesn't guarantee good reception on the client device, as a smartphone may "shout" loudly but have a weak "hearing" (antenna).
Signal level standards: from ideal to interrupted
There is an established gradation of signal levels that allows you to quickly assess the state of the network. Excellent signal The range from -30 dBm to -60 dBm is considered to be the range. All modern speed standards are available in this range, including 4K streaming and lag-free online gaming. Placing the router in the same room as the client typically yields values around -40...-50 dBm.
The range from -60 dBm to -70 dBm can be characterized as good or sufficientWeb surfing, video calls, and Full HD streaming are all stable here. However, when approaching the -70 dBm limit, micro-drops or speed drops may occur if there are many competitors on the air. This is a typical situation in the next room or on the floor below.
Values below -75 dBm are at risk. Connection speeds drop, and data packets begin to be lost, leading to constant reconnections and lag. A signal weaker than -85 dBm is considered unusable for most modern tasks, although text messages can still be sent in instant messaging apps. Below -90 dBm, a device typically loses the network completely.
| Signal level (dBm) | Connection quality | Possibilities of use |
|---|---|---|
| -30... -60 | Excellent | 4K video, VR, online games, large files |
| -60... -70 | Good | HD video, video calls, web surfing |
| -70... -80 | Average / Weak | Mail, instant messaging, low video quality |
| -80... -90 | Bad | Text only, interruptions may occur |
| < -90 | Critical | The connection is absent or unstable |
How to measure signal strength accurately
Operating systems hide precise technical data from the average user, displaying only abstract "sticks." To obtain reliable information about What's the WiFi signal like? arrives on your device, you need to use built-in tools or third-party software. On Windows, the easiest way is the command line. Open the terminal (cmd) and enter the command:
netsh wlan show interfacesIn the list that appears, find the line “Signal”, where the percentage will be indicated, or use more advanced utilities like WiFi Analyzer or Acrylic Wi-Fi, which show a graph in dBm in real time. On macOS, you need to hold down the key Option and click on the WiFi icon in the menu - an extended menu will open with the RSSI (Received Signal Strength Indicator) parameter, which is the desired value in dBm.
Mobile platforms also offer diagnostic tools. On Android, there's often a "Network Information" menu in the WiFi settings section, or you can use apps like WiFi Man or Fritz!App WLANiPhone owners will need to enter engineer mode (via code 3001#12345# in the dialer, if the operator allows it, or through third-party utilities on the PC), since iOS strictly limits access to the radio module's RAW data.
⚠️ Attention: When taking measurements, do not hold your laptop or tablet in your hands—the human body contains a lot of water and significantly shields the signal. Place the device on a table and move 1-2 meters away from it before taking readings.
To get an objective picture, it's recommended to take measurements at different points in the room and at different times of day. In the evening, when neighbors are actively using the internet, the noise level may increase. This won't technically change your signal's dBm value, but it will dramatically reduce the signal-to-noise ratio (SNR), reducing actual speed.
☑️ Checking WiFi quality
Factors Affecting Reception Power
Even if a router is powerful, significant obstacles can block the signal. Wall materials have different absorption capacities. Drywall and wood have little effect on the transmission of waves, losing only 2-4 dBm. Concrete walls with reinforcement can attenuate the signal by 10-15 dBm, and brickwork by 5-10 dBm. Metal structures, mirrors, and tinted glass with a coating can completely block radio waves.
The second important factor is electromagnetic interference. Microwave ovens, which operate at 2.4 GHz, create powerful interference when turned on. Cordless phones, Bluetooth devices, baby monitors, and even LED string lights can all contribute to background noise. In apartment buildings, the main problem is airwaves being clogged by neighboring routers operating on the same or overlapping channels.
The third aspect is the technical condition of the equipment. Router antennas can oxidize or become loose in their connectors over time. Cheap router models often have a nonlinear frequency response (amplitude-frequency response) and amplify the signal unevenly across the range. It's also worth considering that 5 GHz band, which provides high speeds, has less penetrating power and attenuates faster over distance compared to 2.4 GHz.
The effect of an aquarium on WiFi
Water is an excellent absorber of radio waves. A large aquarium placed between the router and laptop can act as a jammer, reducing the signal by 10-20 dBm, which is equivalent to passing through two concrete walls.
Diagnosing problems and background noise
A high signal level (for example, -50 dBm) does not guarantee high speed. A critical parameter is the signal-to-noise ratio (SNR). If your signal is -60 dBm and the noise level in the air is -85 dBm, then the SNR is 25 dB, which is good. However, if neighbors "clog" the air and the noise level rises to -65 dBm, the desired signal is drowned out by interference, and the speed drops to a minimum.
For diagnostics, it's essential to use spectrum analyzers, which show not only your signal strength but also channel occupancy. This visualization helps identify interference "dips" and peaks. Switching from automatic channel selection to a free static channel often provides a stability boost comparable to buying a new, expensive router.
It's also worth checking for CRC (Cyclic Redundancy Check) errors in the network card logs. A large number of errors indicates that data packets are being corrupted during transmission and require retransmission. This is a clear sign of poor radio link quality, even if the connection is technically established.
⚠️ Attention: Router interfaces and mobile apps are subject to update. The location of channel settings, transmitter power, and diagnostic tools may differ from those described. Always consult the latest documentation from your equipment manufacturer.
Practical tips for signal boosting
If your measurements show unsatisfactory results, start with the simplest steps. Move the router to the center of your apartment and elevate it—on a cabinet or shelf. Avoid placing it in enclosed spaces, behind a TV, or on the floor. Antennas should be vertical; if you have multiple antennas, try positioning them at 45-90 degree angles to ensure polarization diversity.
The second step is to optimize the settings. Go to the router's web interface (usually at 192.168.0.1 or 192.168.1.1) and try manually selecting a channel. For the 2.4 GHz band, use only channels 1, 6, or 11, as they don't overlap. For 5 GHz, choose the channel with the least congestion. Make sure the mode is enabled. 802.11n/ac/ax, and not a mixed legacy mode, which can slow down the entire network.
If physical relocation and channel setup don't help, consider technical expansion options. Repeaters are the simplest solution, but not always effective, as they cut speed in half. A more modern approach is to use mesh systems, which create a single seamless network with intelligent client switching between nodes. In extreme cases, for larger homes, the best solution is to install twisted pair (LAN) cable and additional access points in different rooms.
The Myth of Foil Amplifiers
A popular life hack involves using aluminum foil or beer cans to direct the signal. While this physically works (creating a reflector), the effect is often unpredictable and can lead to router overheating or poor reception in other directions. It's better to buy an antenna with the right radiation pattern.
Why does the WiFi signal show 100%, but the internet doesn't work?
The indicator on the device shows the signal strength between your device and the router, but it doesn't check for internet access. The issue could be with your ISP, with your DNS settings, or the router may be frozen and require a reboot. It's also possible you're connected to a guest network without internet access.
Does the number of connected devices affect the signal level in dBm?
The number of devices alone doesn't change the physical signal strength (dBm) emitted by a router. However, the more devices actively transmitting data, the higher the airtime congestion and noise level, which reduces effective throughput and can create the illusion of signal degradation.
Can weather affect indoor WiFi?
The weather outside doesn't directly affect indoor WiFi, as the walls protect it from external factors. However, a strong thunderstorm with lightning strikes can create powerful electromagnetic pulses, causing short-term interference. High humidity theoretically slightly increases signal attenuation, but in an apartment, this effect is negligible.
Is it worth buying a router with more antennas to improve the signal?
Not always. The number of antennas is often a marketing ploy. More important are the antenna type (external vs. internal), their gain (dBi), and MIMO support. A router with three external antennas may perform worse than a modern mesh system with internal antennas but advanced signal processing software.