Calculate signal attenuation between two antennas in a vacuum/free space.
Signal Parameters
Loss Results
Enter distance and frequency
About this calculator
Quick Reference
dDistance in km
fFrequency in MHz
Constant32.44 (for km & MHz)
Inverse SquareLoss ∝ d²
Overview
Free Space Path Loss (FSPL) is the attenuation of radio energy as it propagates through free space. It assumes a clear line-of-sight and no obstacles or reflections.
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Pro Tips
Path loss increases with the square of the distance.
Higher frequencies suffer more path loss than lower frequencies.
This calculation does not include antenna gains—it represents the loss between isotropic antennas.
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Fun Facts
"For a WiFi 2.4GHz signal at 100 meters, the FSPL is approximately 80 dB."
"GPS satellites have a path loss of about 184 dB as they orbit 20,000 km above Earth."
"The 'Inverse Square Law' is the primary reason for FSPL: as the signal spreads out, energy density drops."
