How to measure Wi-Fi strength room by room

To measure Wi-Fi strength room by room, open a Wi-Fi strength meter on your phone, stand in the middle of each room for about 30 seconds and write down the typical reading in dBm. Add a speed test in the rooms that matter most. Repeat with the same phone held the same way, and you have a fair map of your home's Wi-Fi.

What a Wi-Fi strength meter measures

A Wi-Fi strength meter shows the received signal strength of your network at your phone, usually as RSSI in dBm. dBm is a scale for very small amounts of radio power, so readings are negative and closer to zero is stronger. If the scale is new to you, what dBm means explains it.

As typical ranges for Wi-Fi:

−30 to −50 dBm: excellent, usually close to the router
−50 to −60 dBm: very good for anything
−60 to −67 dBm: good, and generally enough for video calls and streaming
−67 to −75 dBm: fair, so expect slower speeds and the odd hiccup
Below −75 dBm: weak, and below about −80 dBm close to unusable

Why bars are not enough

The Wi-Fi icon on your phone squeezes this whole range into three or four steps, and phone makers set the steps differently. A room can show full bars at −62 dBm and still be well below the room next door at −45 dBm. The meter gives you the real difference.

What you need

Your phone, with Wi-Fi on and connected to your home network
A Wi-Fi strength meter or analyzer app, or your phone's Wi-Fi details screen if it shows dBm
A rough sketch of your floor plan, or a list of rooms
About 20 to 30 minutes

How to measure, step by step

Choose one phone for the whole test. Different phones read a few dB apart in the same spot.
Hold it the same way every time, for example upright at chest height. Do not cover the top or back with your hand more than usual.
Start beside the router. Note the reading as your baseline.
Go to the first room and stand in the middle. Wait about 30 seconds, and note the typical value rather than the best or worst.
Take a second reading where you actually use Wi-Fi in that room, such as a desk, sofa or bed.
Note the band if your phone or app shows it, because 2.4 GHz and 5 GHz behave differently.
Repeat for every room, including stairs, landings, the garden and any outbuilding you use.
Run a speed test in the three or four rooms that matter most. Strength tells you about the radio link; speed tells you how it feels in use.

Write each result on your sketch. Within a few minutes, you will see where the signal holds up and where it falls away.

Make the test fair

Small things can skew results. To keep the readings comparable:

Close doors the way they usually are. An open door can add several dB.
Test at a normal time. If the house is usually busy in the evening, test then too.
Keep the router where it is for the whole run. Move it only after the first full test.
Pause downloads and updates on other devices while you run speed tests.

Reading the results

Look for patterns rather than single numbers.

A steady fall with distance is normal. The question is whether the rooms you care about stay above about −67 dBm.
A sharp drop between two neighbouring rooms points to a thick wall, a mirror, a fridge or another obstacle.
One floor much weaker than another suggests the router is too low or too high for your layout.
Good strength but poor speed suggests congestion, interference or a broadband problem rather than coverage.

If one area is far below the rest, treat it as a dead zone. How to find and fix Wi-Fi dead zones covers the fixes. The same walk-and-note method also works for mobile signal, as described in how to find the spot with the best signal in your house.

Repeat after every change

Whenever you move the router, change a channel or add a mesh unit, walk the same route and take the same readings again. Real improvement shows up as several dB in your problem rooms and better speed test results, not just a fuller icon.

How CellRadar helps

CellRadar includes a Wi-Fi Meter, a live Wi-Fi strength meter shown as a gauge, so you can watch the reading change as you move from room to room. The Dead-zone Walk Map lets you walk a room and colours each spot by its measured signal, and the speed test adds download, upload, ping and jitter where you need them. Your readings stay on your phone.

Frequently asked questions

What is a good Wi-Fi signal in dBm?

Around −50 to −60 dBm is very good, and −67 dBm or better is generally enough for video calls and streaming. Below about −75 dBm, expect problems.

Why do my readings jump around?

Wi-Fi signals bounce off walls and furniture, and people moving around change the paths. Swings of a few dB are normal, so use the typical value over half a minute.

Can I measure Wi-Fi strength without an app?

On many Android phones, the details of your connected Wi-Fi network show signal quality, and some show dBm. An app adds live updates and is easier for room-by-room tests.

Should I measure on 2.4 GHz and 5 GHz separately?

If your router uses separate network names for each band, yes. If it uses one name, note which band your phone is on for each reading.