C x W x .052
HR = Sprinkler Minutes
C - coverage area
W - water depth
.052 - (it takes 52 gallons per 1,000 sq feet to soak an area 1 inch deep)
HR - Hose rate (gallons per minute coming out of your hose)
Sprinkler time - How long you should run your sprinkler in minutes
This is a general equation to help calculate the amount of time needed to get the desired coverage.