WiFi Coverage Calculator
Generated infographic and interface snapshot for WiFi Coverage Calculator
Find out how far your access point really throws a signal indoors.
Free WiFi Coverage Calculator Online — Big Das
A 20 dBm transmit power spec on a router box promises little until walls, frequency, and room layout enter the picture. The Big Das WiFi Coverage Calculator turns transmit power, band (2.4/5/6 GHz), wall count and material into a live estimate of indoor coverage radius, floor area, and wall loss — so you can place access points with data instead of guesses.
No login, no survey app — the model runs entirely in your browser.
What Is Indoor WiFi Coverage?
Coverage here means the radius around an access point where clients still receive a usable signal strength (RSSI). Indoors that radius collapses compared with open space because:
- Higher frequencies attenuate faster — 6 GHz loses about 8 dB more than 2.4 GHz over the same distance.
- Walls absorb energy — roughly 3–4 dB per drywall, 6–10 dB per brick wall.
- Furniture, people, and partitions add scattered shadowing loss.
A common design target is -67 dBm at the cell edge for voice/video and seamless roaming; -75 dBm is marginal but workable for light browsing.
How to Use the WiFi Coverage Calculator
- Enter transmit power in dBm (typical APs: 14–23 dBm).
- Pick the band — 2.4 GHz, 5 GHz, or 6 GHz.
- Set the number of walls between the AP and the furthest client, and their material (drywall, brick, or concrete).
- Choose the edge-of-coverage target — -67 dBm for good, -75 dBm for marginal.
- Select the indoor layout — open plan (n=2.5), typical (n=3), or obstructed (n=4).
- Read the results — headline radius, circular coverage area, total wall loss, and a comparison of both RSSI targets appear instantly.
The Formulas Used
Free-space ref at 1 m: FSPL(1m) = 20·log10(4π·f / c)
≈ 40.1 dB @ 2.4 GHz, 47.2 dB @ 5 GHz, 47.9 dB @ 6 GHz
Indoor log-distance: PL(d) = FSPL(1m) + 10·n·log10(d) + Σ wall losses
Coverage radius: d = 10^((TX
- RSSI_target - walls
- FSPL(1m)) / (10·n))
Coverage area: A = π·d²
This is the widely used ITU-R-style indoor propagation model: a free-space anchor at 1 m with a log-distance exponent n and discrete wall attenuation.
Worked Example
Typical home router: *20 dBm
- TX on 2.4 GHz, two drywall walls (3.5 dB each), targeting -67 dBm, typical layout n=3:
Wall loss = 2 × 3.5 = 7 dB
Budget = 20 - (-67)
- 7
- 40.1 = 39.9 dB available over distance
Radius = 10^(39.9/30) ≈ 21 m
Area = π × 21² ≈ 1,410 m²
Switch to 6 GHz (FSPL(1m) = 47.9 dB there) and the same router covers only about 11.7 m before hitting -67 dBm — roughly 1.8× less radius through the walls, which is why WiFi 6E/7 mesh nodes are placed closer together.
Common Use Cases
- AP placement: Decide how many access points a floor needs before installing them.
- Band selection: Quantify the 2.4 vs 5 vs 6 GHz range trade-off for a floor plan.
- Mesh planning: Check whether a satellite node can still hear the main router through your walls.
- Site-survey prep: Produce a first-pass coverage guess to validate against a real survey.
Frequently Asked Questions
Why is my measured coverage smaller than the estimate?
The model assumes circular coverage through evenly distributed walls of one type. Real-floor mirrors, metal ducts, low-E glass, and human bodies add shadowing loss, so treat the result as an optimistic design figure and leave a few dB of fade margin.
What does the n exponent actually represent?
n is the path-loss exponent: how fast signal decays with distance. n=2 is free space; corridors can dip below 2; cluttered indoor spaces push n toward 4. This tool offers 2.5, 3, and 4 for typical office/home layouts.
Is -67 dBm the right target?
-67 dBm is the industry standard edge for voice, video, and fast-roaming applications (CCX/enterprise guidance). -75 dBm works for email and web. If you only browse, select -75 and enjoy a deliberately larger radius.
Does antenna gain count?
Yes — add the AP antenna gain to the transmit power figure (e.g. 20 dBm conducted + 3 dBi antenna behaves like 23 dB EIRP toward the client). Regulatory limits apply to EIRP, not conducted power.
Why does 6 GHz cover less area than 2.4 GHz?
Free-space loss rises with frequency: about 47.9 dB at 1 m for 6 GHz versus 40.1 dB for 2.4 GHz. That ~8 dB deficit is roughly 1.8× less distance at the same RSSI (at n=3), before any wall count — and walls also absorb 5/6 GHz more strongly.
Can I use this for outdoor point-to-point WiFi?
Not reliably — outdoor links follow a two-ray or free-space model (n≈2) with Fresnel-zone clearance requirements that this indoor tool doesn't model. Use the free-space reference radius it prints only as a rough bound.