It works the same way, when you plan to load weight...
As a rule of thumb (in Bell helicopters), you can subtract for each person (app. 100 kg including baggage) 0.1 kp/cm2 (Torque) which equals 3% Torque...
So-if you have 15% Power to Max left when overflying the area, you can just subtract the expected pax-weight and see, if you have enough power left for T/O BEFORE you land in that area.....
