how many btus in a gallon of diesel fuel
btu per pound * pounds per gallon   OK, it sounds as if you know the value of fuel in oil btu per pound.Now find out how much a gallon of fuel oil weighs and multiply the bâ¦tu value x that weight in pounds and that is the value per gallon. Or simply, diesel fuel is #2 fuel oil which contains 140,000 btu per gallon.