A free, browser-based Thread network coverage planner. Upload your floorplan, place your border routers and Thread routers, and see where your Matter-over-Thread devices will — and won't — have signal. No signup, no download, nothing leaves your browser.
No other browser tool does predictive Thread coverage planning — heatmap, contour lines, PNG export.
How it works
PNG or JPG of your home. Calibrate the scale from one known wall length, then draw your walls by material — drywall, glass, brick, concrete.
Drop devices from presets — Apple TV 4K, HomePod mini, Nest Hub (2nd gen), HA ZBT-1, eero 6, Nanoleaf bulbs — or set radio parameters by hand.
The 802.15.4 heatmap and contour lines render live. Drag devices around to close dead spots, then export the plan as a PNG.
The physics
Thread runs on IEEE 802.15.4 radios at 2.4 GHz — the same radio family as Zigbee. Typical indoor range is 10–20 m through walls: transmit power is low by design (these are battery-friendly radios), so every wall on the path matters far more than the number printed on the box.
The planner computes received signal at every point of your floorplan using the COST-231 multi-wall model: free-space path loss over the real distance, minus the summed attenuation of every wall the signal crosses, by material. These are the per-wall values it applies at 2.4 GHz:
| Material | Attenuation | Notes |
|---|---|---|
| Drywall / partition | 3 dB | Single plasterboard sheet on metal or timber studs. |
| Glass | 2 dB | Standard glazing. Low-E coatings attenuate more. |
| Brick | 8 dB | Solid clay; hollow brick behaves similarly. |
| Concrete | 15 dB | Poured / block walls. Rebar pushes this higher. |
Two brick walls between a border router and a bedroom sensor cost 16 dB; make one of them concrete and it's 23 dB — often the difference between a device that responds instantly and one that shows "no response" in the app. Expect predictions within ±6–10 dB of a real measurement in a typical home — enough to make placement decisions, not laboratory precision. The accuracy page documents the full model and its limits.
Thread, specifically
Thread is a mesh — but not every device meshes. Getting these three roles right is most of the battle.
A Thread border router connects the mesh to your home network. You likely already own one: Apple TV 4K, HomePod mini or HomePod (2nd gen), Google Nest Hub (2nd gen or later), eero 6 and newer, or a Home Assistant SkyConnect / Connect ZBT-1 running OpenThread Border Router. Running multiple border routers on one fabric improves resilience — the mesh survives any single one going offline.
Any mains-powered Thread device — a smart plug, an always-powered bulb like Nanoleaf Essentials — acts as a Thread router and forwards traffic, growing your coverage with every device you add. Battery devices don't: sensors and buttons are sleepy end devices that must reach a powered router directly. A home full of battery sensors and one border router is a star, not a mesh.
Devices commissioned through different ecosystems — Apple Home here, Google Home there — can end up on separate Thread networks with separate credentials that don't route for each other. Credential sharing has improved with Matter, but it remains a real-world gotcha. If a device "should" be in range and still drops, check which network it actually joined before blaming the radio.
Built-in device presets in mesh mode
Anything not listed: set transmit power and antenna gain by hand.
FAQ
A Thread border router is the device that bridges your Thread mesh to your regular home network (WiFi/Ethernet), so your phone and hubs can reach Thread devices. Common border routers you may already own: Apple TV 4K, HomePod mini, HomePod (2nd gen), Google Nest Hub (2nd gen or later), eero 6 and newer, or a Home Assistant SkyConnect / Connect ZBT-1 dongle running OpenThread Border Router. Without at least one border router on your network, Matter-over-Thread devices cannot be reached at all.
One border router is enough to form a Thread network, but a single unit in the living room often cannot reach devices behind several walls — Thread's 2.4 GHz 802.15.4 radio typically covers 10–20 m indoors through walls. Adding a second or third border router on the same fabric improves both coverage and resilience: if one goes offline (or gets unplugged), the mesh stays reachable through the others. The honest answer is "it depends on your walls" — which is exactly what this planner computes. Draw your floorplan, place your border routers, and the heatmap shows whether one is enough.
The two most common causes are radio and fabric. Radio: battery-powered Thread devices are "sleepy end devices" — they do not route and must reach a mains-powered Thread router or border router directly. If that hop crosses a brick (≈8 dB) or concrete (≈15 dB) wall at the edge of range, the device drops in and out. Fabric: if your devices were commissioned through different ecosystems (Apple Home vs Google Home), they can end up on separate Thread networks with separate credentials — credential sharing has improved with Matter, but it is still a common gotcha. Plot your devices on a floorplan first to rule out the radio cause.
Practically the same. Thread and Zigbee both use IEEE 802.15.4 radios at 2.4 GHz, so a wall attenuates them identically and typical indoor range is 10–20 m through walls for both. The difference is topology and networking, not physics: Thread is IP-based and self-healing with multiple border routers, while Zigbee routes everything through a single coordinator. If you are comparing protocols for a specific home, plan the same floorplan in both modes — we have a separate Zigbee planner too.
No. Only mains-powered Thread devices (smart plugs, always-powered bulbs like Nanoleaf Essentials, wired sensors) can act as Thread routers and forward traffic for other devices. Battery devices — door sensors, buttons, air-quality monitors — are sleepy end devices: they wake briefly, talk to their parent router, and go back to sleep. A house full of battery sensors and one border router is a star, not a mesh. The planner distinguishes the two roles so your coverage map reflects reality.
The engine runs the COST-231 multi-wall propagation model at 2.4 GHz: for every point on the floorplan it counts each wall on the path from every border router and Thread router, subtracts the per-material attenuation (drywall 3 dB, glass 2 dB, brick 8 dB, concrete 15 dB), and reports the strongest result. Expect predictions within ±6–10 dB of a real measurement in a typical home — enough to decide where a border router should go and whether the garage sensor will stay connected. See the accuracy page for the full methodology.
Related
Zigbee mesh planner →
Same 802.15.4 radio at 2.4 GHz, coordinator-based topology. Hue, IKEA, Aqara, Zigbee2MQTT.
Z-Wave mesh planner →
Sub-GHz radio with better wall penetration and longer range — different physics entirely.
Why your mesh has dead spots →
A walkthrough of 802.15.4 dead-spot causes and how to fix them with router placement.
How accurate is this? →
The COST-231 multi-wall model explained, with the full ±6–10 dB accuracy envelope.
Planning WiFi instead? The WiFi heatmap planner is the same engine tuned for 2.4 / 5 GHz access points.
Draw your walls, place a border router, and watch the mesh heatmap render live. Free for up to 5 devices — no signup, and your floorplan never leaves the browser.