I am frustrated! I used a measuring wheel and stopwatch--and found that I covered 320 feet per minute. Mounted stopwatch on handlebars. At 10 feet wide that is 3200 sqft per minute. at 3 pounds per thousand that is 5 minutes and 11 seconds per 50 pound bag. But it is never the same. And it doesn't always match with the lawn size. I am lucky to get within 13 or 14 percent.