¹LOAD = Average % of horsepower demanded & typical load factors are 0.6 for light loads (planting, etc.) and 0.7 for heavier loads (plowing, etc.)

²gals/hr = FE *(LOAD*PTO)
FE = Fuel Efficiency illustrated below:
Diesel: FE = .52 * LOAD + .77 - (.04 * sqrt(738 * LOAD + 173))
Gasoline: FE = .54 * LOAD + .62 - (.04 * sqrt(697 * LOAD))

³hrs/ac = 1/FC
FC (Acres/hour) = S*W*FE/8.25
S = Speed in MPH
W = Width of implement in feet
FE = Typical Field efficiencies range from 65%-80%
8.25 = a constant