Every manufacturer has charts as to how many acres per hr. their machines will mow, but seldom can we as LCO's find a property that allows us to keep the machine mowing at full speed 100% of the time. I mowed a grass airstrip yesterday - It is 3100 ft. long, and smooth. Made 5 rounds with the 9 1/2 foot mower (10 min. per round - 50 min. total) all at peddle to the metal. Figuring a 6" overlap (being conservative, probably more like 3"), that is 18 feet per round, x 5 = 90' x 3100 =279,000 sq. ft. divided by 43,560 = 6.4 acres. 6.4 acres divided by 5 = 1.28 acres every 10 min. x 6 =7.68 acres per hr.