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Wi-Fi Signal Loss (FSPL) Calculator

Estimate free-space path loss for a wireless link at a given distance and frequency.

Inputs

Saved Scenarios

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Free-Space Path Loss (dB)

80.04

Spark says

How it's calculated

Formula

FSPLdB=20log⁡10(dkm)+20log⁡10(fMHz)+32.44FSPL_{dB} = 20\log_{10}(d_{km}) + 20\log_{10}(f_{MHz}) + 32.44
d_{km}, f_{MHz}
— Distance in kilometers, frequency in megahertz

What is the Wi-Fi Signal Loss (FSPL) Calculator?

Free-space path loss (FSPL) is the signal attenuation a radio wave experiences traveling through open space with no obstructions — it's the theoretical floor for wireless link loss, used as a baseline before accounting for walls, foliage, and other obstacles.

How to use it

  1. 1 Enter the distance between transmitter and receiver.
  2. 2 Choose the frequency band.

Worked examples

100m at 2.4 GHz

About 80.0 dB of free-space path loss.

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Limitations

  • •Assumes perfectly clear line of sight — real-world loss is always higher once walls, trees, weather, and interference are factored in.

Frequently asked questions

Why does higher frequency mean more path loss?

Higher-frequency signals have shorter wavelengths, which are absorbed and scattered more readily by obstacles and even air molecules — this is why 5GHz Wi-Fi has shorter range than 2.4GHz at the same power.