Wi-Fi heatmap: what it is and how to make one at home
Network engineers have used heatmaps for years to plan Wi-Fi in offices. You can make one for your home with a phone, and it takes minutes.
In this guide
A Wi-Fi heatmap is a floor plan colored according to how good the Wi-Fi is in each spot. Strong coverage shows up in cool colors, weak spots in warm colors, and dead zones in red. Instead of a list of speed test numbers, you get a picture of your home where the problem areas are impossible to miss.
Why a heatmap beats a speed test
A speed test answers one question: how fast is the connection right here, right now? It says nothing about the room next door, and it mixes two different things together: your Wi-Fi and your internet line.
A heatmap answers a more useful question for a home: where does the Wi-Fi get worse, and by how much? That's what tells you whether to move the router, where to put a mesh node, or whether you need extra hardware at all.
How a Wi-Fi heatmap is made
Every heatmap, from professional tools to phone apps, follows the same three steps:
- A floor plan. The map needs the shape of your rooms, so each measurement can be placed where it was taken.
- Measurements while you walk. You move through the space and the tool records Wi-Fi quality at many points.
- Interpolation. The tool fills the gaps between measurements and colors the whole plan, so you see continuous areas instead of scattered dots.
Professionals doing an office survey use laptops with dedicated survey software and measure the raw radio signal in dBm. For a home, what matters is simpler: where your devices actually struggle.
How to make a Wi-Fi heatmap with your iPhone
With WiFi Heatmap the whole process happens on your iPhone:
- Create the floor plan. Walk through your home and draw the rooms you want to check.
- Measure room by room. Walk slowly through each room. The app records how your connection responds wherever you stand.
- Read the map. Each room gets a color and a quality score out of 100, and the weakest areas stand out immediately.
One detail worth knowing: iOS doesn't let apps read the raw Wi-Fi signal value, so no App Store app can show true dBm on an iPhone. WiFi Heatmap measures connection quality instead, which is what you feel when a video buffers. If you're curious about signal readings specifically, see how to check Wi-Fi signal strength on iPhone.
Tips for an accurate map
- Measure your home as you really use it. If the bedroom door is usually closed, close it.
- Hold the phone the way you normally do. A phone on a desk and a phone in your hand at chest height get slightly different results.
- Walk slowly and cover the spots that matter. The sofa, the desk, the bed and the kitchen table are more important than the back of a closet.
- Map one network at a time. If you have an extender with a separate network name, map each network separately.
- Re-map after every change. Moving the router by one meter can change the map more than you'd expect.
- Try another time of day if results seem odd. Evenings are often worse in apartment buildings, when every neighbor is streaming.
How to read the colors
| Color | What it means | What you'll notice |
|---|---|---|
| Cyan / green | Strong connection | Video calls and 4K streaming work smoothly |
| Yellow | Fair | Browsing is fine, video may drop in quality |
| Orange | Weak | Buffering, slow loading, choppy calls |
| Red | Dead zone | Pages stall or the device disconnects |
The most useful thing on a heatmap isn't a single color but the shape of the change:
- Colors fade gradually with distance: the router is too far from the rooms you use. Move it toward the center, as explained in where to put your router.
- A sharp edge at one wall: that wall is the problem. A small change in router position or a mesh node on the other side usually solves it.
- A whole floor is red: the floor slab is blocking the signal. A second access point on that floor is the reliable fix. Compare the options in mesh vs Wi-Fi extender.
Frequently asked questions
Is there a free Wi-Fi heatmap app for iPhone?
Several apps let you try heatmaps on iPhone, and some offer free features. Keep in mind that none of them can show real dBm values on iOS: they measure connection quality in other ways. Look for an app that builds a floor plan of your home, so the results are tied to real rooms.
What's the difference between a Wi-Fi heatmap and a coverage map?
At home they are the same thing: a map of how good your Wi-Fi is in each area. Internet providers also publish "coverage maps", but those show which neighborhoods a provider serves, not how Wi-Fi behaves inside your home.
How often should I make a new heatmap?
Whenever something changes: a new router, a moved router, a mesh system, or new furniture in the way. It's also worth re-mapping when a room that used to be fine starts giving problems.
Can a heatmap tell me where to put a mesh node?
Yes, and that's one of its best uses. Place the node where the map is still green or yellow, on the way toward the red area, not inside the dead zone itself. A node that receives a weak signal can only pass on a weak signal.