WiFi Coverage Calculator
Estimate the theoretical free-space WiFi coverage distance using a link budget. Includes receiver antenna gain, fade margin, maximum allowable path loss, and estimated range.
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Enter parameters and click Calculate to view results
Formula & Theory
FSPL = EIRP + Gr − Sensitivity − Fade Margin | d(km) = 10^((FSPL − 32.44 − 20log₁₀(fMHz))/20)This formula is used to calculate antenna parameters for wifi coverage calculator.
Overview
The WiFi Coverage Calculator estimates the theoretical free-space range of a WiFi link using a full RF link budget: EIRP, receiver antenna gain, receiver sensitivity, and fade margin. Enter your transmitter's effective radiated power, the receiving antenna's gain, the receiver's sensitivity threshold, and a fade margin to account for real-world variability, and the calculator returns the maximum allowable free-space path loss and the corresponding estimated range in meters and kilometers, along with automatic identification of the 2.4 GHz, 5 GHz, or 6 GHz WiFi band. This tool is useful for network planners, WISPs, point-to-point wireless bridge designers, IoT deployment engineers, and anyone estimating outdoor or line-of-sight WiFi range before installing access points, antennas, or long-range wireless links.
Input Guide
Enter Frequency exactly as shown on the calculator. Confirm every unit, selected option, and decimal position before calculating so the wifi coverage result matches the intended wireless communication design case.
Output Guide
The output section reports WiFi Band, Maximum Free-Space Path Loss, Estimated Free-Space Range, Link Budget, Fade Margin, Design Note for the values you entered. Use these values as design targets, then compare them with available space, component limits, feed system behavior, installation environment, and measured performance before finalizing the design.
How This Calculator Works
The WiFi Coverage applies FSPL = EIRP + Gr − Sensitivity − Fade Margin | d(km) = 10^((FSPL − 32.44 − 20log₁₀(fMHz))/20) to the entered values. Estimate the theoretical free-space WiFi coverage distance using a link budget. Includes receiver antenna gain, fade margin, maximum allowable path loss, and estimated range. Use the result as a first-pass wireless communication target, then validate it against losses, tolerances, mounting, nearby conductors, feed-line effects, and measurement conditions.
Design Notes
This calculator models free-space path loss (FSPL), which assumes a clear, unobstructed line of sight between transmitter and receiver with no reflections, absorption, or interference — conditions that rarely exist indoors and are only closely approximated outdoors over open terrain or point-to-point links between elevated antennas. Higher frequency bands attenuate faster over distance for the same power level: at equal EIRP and receiver sensitivity, a 6 GHz link will show shorter free-space range than an otherwise identical 2.4 GHz link, which is why 6 GHz WiFi 6E and WiFi 7 deployments favor higher-density access point placement despite offering more spectrum and less congestion. Fade margin is critical for real-world reliability: it reserves headroom in the link budget for multipath fading, minor obstructions, weather, and interference so the link doesn't drop out under normal signal variation, and 10-20 dB is a common planning target for outdoor point-to-point links, while indoor or high-interference environments often warrant even more margin. Receiver sensitivity, typically specified in the device datasheet, sets the noise floor the signal must clear for a usable connection; more negative sensitivity values (like -85 dBm vs. -70 dBm) indicate a more sensitive receiver capable of decoding weaker signals, directly extending achievable range.
Build and Tuning Notes
Treat the free-space range from this calculator as a theoretical ceiling, not an expected real-world result — indoor deployments should apply substantial additional loss for walls, floors, furniture, and human bodies (drywall alone can cost several dB per wall at 2.4 GHz and more at 5/6 GHz), while outdoor deployments should account for foliage, terrain, and Fresnel zone clearance around the direct path between antennas. For outdoor point-to-point or point-to-multipoint bridges, verify that the Fresnel zone between antennas is at least 60% clear of obstructions at the calculated distance, since partial Fresnel zone blockage can degrade the link well below the free-space estimate even with adequate link budget on paper. When estimating EIRP, remember it already combines transmit power and transmit antenna gain (EIRP = Tx power + Tx antenna gain − cable/connector losses), so don't double-count antenna gain by adding it again separately. For real-world validation, use a WiFi site survey tool or signal strength app to measure actual RSSI at your target coverage boundary and compare it against the receiver sensitivity used in this calculation — if measured signal falls well short of predicted range, obstructions, interference, or antenna orientation are the most likely causes, and effective isotropic radiated power should be checked against your local regulatory limits, which cap maximum EIRP for unlicensed WiFi bands.
Inputs used by this calculator
- Frequency — use MHz.
- EIRP — use dBm.
- Receiver Antenna Gain — use dBi.
- Receiver Sensitivity — use dBm.
- Fade Margin — use dB.
Frequently Asked Questions
What is EIRP and how is it different from transmit power?
EIRP (Effective Isotropic Radiated Power) is the total effective power radiated in the direction of maximum antenna gain, combining the radio's transmit power with the antenna's gain minus any cable and connector losses. It represents the actual power level "seen" by a receiver, which is why link budgets use EIRP rather than raw transmit power alone.
Why is my real-world WiFi range much shorter than the calculated free-space range?
This calculator models ideal free-space propagation with no obstructions. Walls, floors, furniture, trees, terrain, and interference from other wireless devices all add loss beyond free-space path loss, often reducing indoor range to a small fraction of the theoretical free-space estimate.
How much fade margin should I use for a WiFi link budget?
A fade margin of 10-20 dB is a common starting point for outdoor line-of-sight links, providing headroom against multipath fading, weather, and minor obstructions. Indoor or high-interference environments, and links intended for high reliability, often warrant a larger fade margin.
Does 6 GHz WiFi have shorter range than 2.4 GHz WiFi?
Yes, at equal power and receiver sensitivity, higher-frequency signals like 6 GHz attenuate faster over distance than lower-frequency signals like 2.4 GHz, resulting in shorter free-space range. This is a fundamental tradeoff of moving to higher, less congested spectrum in WiFi 6E and WiFi 7 networks.
What receiver sensitivity value should I use for my WiFi device?
Check your access point, router, or client device's datasheet for its rated receiver sensitivity at the data rate you plan to use, typically expressed in dBm (e.g. -80 dBm to -95 dBm). More negative values indicate greater sensitivity and generally support longer range at a given data rate.
Is this calculator accurate for indoor WiFi coverage planning?
It provides a useful theoretical upper bound, but indoor environments involve significant additional path loss from walls, floors, and furniture that free-space path loss does not account for. For indoor coverage planning, this calculator is best used alongside a proper site survey or RF planning tool that models building materials and layout.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.