What's a good Wi-Fi signal: dBm definition

Many users encounter a situation where the internet on their smartphone or laptop is unstable, even though the router appears to be on and the lights are flashing. Often, the problem lies not with the ISP, but with the strength of the received radio signal, which is difficult to assess without specialized knowledge. Understanding What is considered a good Wi-Fi signal?, is the key to stable operation of the home network and the absence of "buffering" when watching videos.

In technical documentation and network analysis apps, reception power is most often measured in negative decibel-milliwatt (dBm) values. The minus sign can be intimidating to beginners, but in radio wave physics, it's the norm, denoting the logarithmic ratio of signal power to a reference level of 1 milliwatt. The closer the value is to zero, the stronger the signal, and vice versa: the higher the number after the minus, the weaker the connection.

In this article, we'll examine which indicators should be considered benchmarks and which ones indicate coverage issues. We'll also examine the impact of frequency bands. 2.4 GHz And 5 GHzWe'll also discuss diagnostic methods that will help you optimize your wireless network without purchasing expensive equipment.

Wireless Physics and Negative Values

To correctly interpret diagnostic data, it's important to understand the nature of the measured value. A Wi-Fi signal is an electromagnetic wave, and its power is dissipated in space during transmission. Since the power received by a smartphone antenna is typically much lower than the reference milliwatt, the logarithm of the ratio becomes negative.

It is critical to remember the rule: In the dBm scale, a smaller absolute value (e.g. -40) is always better than a larger value (e.g. -80)This often causes confusion because in normal math, -80 is less than -40, but in the context of signal strength, -40 dBm means much more powerful and stable reception.

Values ​​can fluctuate depending on a variety of factors, including distance to the access point, the presence of obstacles, and the performance of neighboring networks. Understanding this scale allows you to avoid guesswork and accurately determine when your router needs to be reconfigured or relocated.

Signal level chart: from ideal to lost connection

For a quick assessment of network status, it's convenient to use signal strength gradations. Although different Wi-Fi chip manufacturers may introduce slight measurement errors, the general connection quality standards remain consistent across all devices.

Below is a table to help you classify the current state of your network. Note the thresholds beyond which data transfer issues begin.

It's worth noting that requirements may vary for different tasks. For browsing social media news feeds, -75 dBm is sufficient, while transferring large files over a local network or online gaming will require a level of at least -60 dBm.

Differences between the 2.4 GHz and 5 GHz bands

Modern routers operate in two main frequency ranges, and the signal standards for them differ slightly due to the physical properties of radio waves. Range 2.4 GHz has better penetration ability, but is more susceptible to interference from household appliances and neighboring networks.

Range 5 GHz It provides higher speeds and is less congested, but its waves penetrate walls less well and fade more quickly over distance. Therefore, a "good" 5 GHz signal in a distant room may be physically unreachable without additional access points.

⚠️ Attention: If you're far from the router behind several walls, your phone may automatically switch to 2.4 GHz even if 5 GHz is technically available. This can result in a drop in speed, although the signal strength in dBm will seem acceptable.

When analyzing a network, it's important to consider the frequency you're using. A value of -65 dBm on 5 GHz is excellent, ensuring high speed. The same value of -65 dBm on 2.4 GHz in an apartment building could indicate severe noise pollution, leading to significant speed losses despite good reception.

Why does 5 GHz fade faster?

High frequency waves (5 GHz) have a shorter wavelength, which makes them more susceptible to absorption by moisture (including that contained in walls and plants) and reflection from surfaces.

Factors Affecting Indoor Signal Attenuation

Even if the router is powerful, the signal may not fully reach the user's device. The main enemies of Wi-Fi are physical obstacles and electromagnetic interference. Wall material plays a crucial role: drywall allows the signal to pass through almost freely, concrete significantly weakens it, and metal reinforcement or foil-clad insulation can block the connection completely.

It's also worth considering sources of interference. Microwave ovens operating at 2.4 GHz can create powerful, short-term bursts of noise. Aquariums, mirrors, and even thick wooden doors can interfere with the coverage map.

• 🏗️ Wall materials: Reinforced concrete floors can reduce the signal level by 10-20 dBm, turning a “good” signal into a “bad” one.
• 📺 Household appliances: An operating microwave or baby monitor can create noise that does not formally reduce the dBm level, but does degrade the signal-to-noise ratio (SNR).
• 📶 Neighborhood networks: In apartment buildings, dozens of routers can operate on the same channels, creating a "mess" of radio waves, especially in the 2.4 GHz range.

The placement of the router's antennas also matters. Omnidirectional antennas (like a baton) provide good signal coverage horizontally, but significantly weaker signal coverage above and below the router (vertically). Therefore, placing a router on the floor or directly under the ceiling is often a mistake.

How to measure signal strength on different devices

Built-in operating system tools are often insufficient for obtaining accurate signal strength data, as they only display abstract "bars." For professional diagnostics, it's better to use specialized software that displays the exact numeric value in dBm.

On computers running Windows You can use the command line or third-party utilities. On smartphones, the situation is even simpler: most Android devices have built-in engineering menus or support analysis apps. For owners iOS (iPhone/iPad) requires an app AirPort Utility from Apple, which requires you to activate the hidden scanner mode in the app's settings.

One of the easiest methods on Windows is to use the command line. Open the terminal (cmd) and enter the command:

netsh wlan show interfaces

In the list that opens, find the line "Signal", where the percentage will be indicated, or use third-party programs like WiFi Analyzer, which immediately show the graph and the exact value in dBm in real time.

⚠️ Attention: Signal-measuring apps on Android may require geolocation permission. This is a system-wide restriction required for Wi-Fi network scanning, and it doesn't mean the app is tracking your location.

Methods of enhancing and optimizing reception

If measurements show that the signal in key areas of the apartment is weaker than -70 dBm, action is needed. The easiest and most cost-effective way is to relocate the router. Move it higher, remove it from enclosed spaces, and try to place it closer to the center of the apartment or where you primarily use the internet.

If rearranging doesn't help, you can try changing the broadcast channel to a less crowded one. In the 2.4 GHz band, it's best to choose channels 1, 6, or 11, as they don't overlap. For the 5 GHz band, there's a wider selection of channels, and the router's automatic mode usually handles this well.

• 🔄 Replacing antennas: If the router has removable antennas, they can be replaced with more powerful ones (with a higher gain, dBi).
• 📡 Repeaters and Mesh systems: For large areas, a single router isn't enough. A repeater will replicate the signal, and a mesh system will create a single, seamless network with intelligent switching between nodes.
• 🔌 Powerline adapters: If the radio signal does not penetrate the walls, you can transmit the Internet through electrical wiring, creating a new access point in the desired room.

It's also important to check whether your router is outdated. Models ten years old may not support modern encryption standards and signal modulation methods, which limits maximum speed even with perfect reception.

Does weather affect Wi-Fi signal inside the home?

The weather outside has virtually no direct impact on the indoor signal, as the walls of the house shield most external influences. However, a strong thunderstorm can create electromagnetic interference, and very high humidity theoretically slightly increases the attenuation of high-frequency waves (5 GHz), but in an apartment, this change is imperceptible to the user.

Is it true that putting foil on an antenna will boost the signal?

Using foil or "cans" on an antenna is a popular myth. Theoretically, a directional reflector can focus the signal in one direction, but in practice, homemade designs often disrupt the antenna's alignment, resulting in signal reflection back to the router and even damaging the transmitter. It's more effective to purchase an antenna with the right radiation pattern.

Can a router break down and start giving a weak signal?

Yes, electronic components, especially the power supply and radio module, can degrade over time. If the router gets very hot, dust clogs the ventilation, or the power supply produces unstable voltage, the transmitter power may drop, resulting in a weakened signal across the board.