How to Check Wi-Fi Signal Strength on Windows, Mac, iPhone and Android — and Read the dBm

The Wi-Fi icon’s bars tell you very little: three bars on one device can be a strong signal, on another a mediocre one. To find dead spots, place a router or mesh node, or tell weak signal from other problems, you need the actual number. Here is how to read it on every common device and what the numbers mean.

Bars, Percent and dBm

Bars are each manufacturer’s own simplification; they differ between phones and laptops and hide the details.

Percent (Windows) is a signal-quality score from 0 to 100. Better than bars, but not standardised.

dBm is the actual received signal power, sometimes labelled RSSI. Values are negative: the closer to zero, the stronger. Every 3 dB is roughly half or double the power, so −70 dBm is far weaker than −60 dBm, not just a little.

Noise and SNR. Some tools also show the noise level (for example −95 dBm). The difference between signal and noise is the signal-to-noise ratio (SNR). A strong signal in a noisy environment can still perform badly; see Wi-Fi interference.

What Is a Good Wi-Fi Signal?

Cisco’s best-practice guide for Apple devices on Wi-Fi gives concrete thresholds: the optimal edge of coverage for iPhones and iPads is −67 dBm or better (−65 dBm in dense environments), Mac computers can accept −72 dBm, and a signal-to-noise ratio of at least 25 dB should be maintained. The same guide notes that iPhones start looking for a better access point when the signal falls below −70 dBm, and Macs below −75 dBm.

As a practical rule of thumb for home use:

The ranges below the Cisco thresholds are a common guideline, not a standard; real performance also depends on noise, the band and the devices.

Windows

Open Command Prompt and run:

netsh wlan show interfaces

The Signal line shows the quality in percent for the connected network, alongside the band, channel and receive and transmit rates. Run it again in different spots to compare. Roughly, values above 80% are strong, 60–80% are fine, and below 50% you will notice problems.

For dBm readings and a view of all nearby networks, use a Wi-Fi analyzer app from the Microsoft Store.

Mac

Hold the Option key and click the Wi-Fi icon in the menu bar. Under your network you see technical details, including RSSI (the signal in dBm) and Noise. Subtract the noise from the RSSI to get the SNR: −60 dBm signal and −92 dBm noise gives 32 dB.

The same menu offers Open Wireless Diagnostics, whose Scan window lists nearby networks with their signal and channels.

iPhone and Android

iPhone and iPad do not show dBm in Settings. Apple’s free AirPort Utility app includes a Wi-Fi scanner, which Apple describes in its enterprise roaming guide: go to Settings → AirPort Utility and turn on Wi-Fi Scanner, then open AirPort Utility, tap Wi-Fi Scan and Scan. The results list each network with its RSSI and channel.

Android shows the signal strength as a word (Excellent, Good, Fair, Weak) in the details of the connected network under Settings → Network & internet → Internet. For dBm values, use a Wi-Fi analyzer app.

In the Router or App

Many router apps and web interfaces list each connected device with its signal level, often in dBm. That view is useful because it shows what the router hears from the device — the weaker side of the link for phones and smart gadgets. Look for the device list or client list; see who is connected to my Wi-Fi. Mesh apps often show the link quality between units as well.

How to Measure Your Home Properly

1. Pick one device and use it for all readings, since devices differ.
2. Measure next to the router as a reference, then in each room where you use Wi-Fi — at the spot where you sit, not in the doorway.
3. Note the band. 5 GHz always reads weaker than 2.4 GHz at the same spot because it fades faster through walls; that is expected.
4. Repeat a few times; readings fluctuate by several dB.
5. Add a speed test in the weakest rooms to see the real effect.

The result is a simple map of where coverage is good and where it is not.

What to Do About a Weak Signal

Move the router to a central, open spot, off the floor and away from metal and appliances; see how to boost your Wi-Fi signal.

Check for interference if the signal looks fine but the connection still struggles; see Wi-Fi interference.

Add coverage where the signal stays below about −70 dBm: a mesh node, an extender placed halfway, or an access point on a cable; see mesh Wi-Fi vs extender.

Use a cable for stationary devices in weak spots; see Ethernet vs Wi-Fi.