For cooped birds, that doesn't sound too bad, especially if they are heavier birds and not leghorns which weigh about 4 lbs and is the basis of about 90% of the "feed requirement" info you can find.
My 22 adults (5 are banties), they go though about 100 lbs a month... but that is supplemented with about 4-6 gallons of scrap food/left over/ bakery ends a week, and complete free range from sun up to sun down on very buggy partially tree covered partially tilled, and partially grassy acerage (ie. very goodie filled land). They spend the night in the coop, and what ever time they want to spend in there nibbling before and after laying eggs.