Work out free space loss (wi fi) instantly with clear inputs, formula shown and shareable results.
Free space path loss is 20log10(distance in km) + 20log10(frequency in MHz) + 32.45 dB, so loss rises 6 dB every time distance doubles and about 7.4 dB moving from 2.4 to 5 GHz. That frequency penalty is why 5 and 6 GHz cells are inherently smaller than 2.4 GHz ones at the same power.
Free space path loss
FSPL(dB) = 20 log10(d_km) + 20 log10(f_MHz) + 32.45; received = EIRP - FSPL - obstruction loss
Higher frequency means higher free-space loss and worse wall penetration. The trade is enormous spectrum with no legacy interference.
A plasterboard wall costs around 3 dB, a brick wall 6 to 10, concrete 10 to 20, and a foil-backed insulated wall or lift shaft can exceed 30 dB.