Figuring out sprinkler zones and head counts before you rent a trencher will save you from digging twice. Enter your lawn area and get a rough layout with head count, zone count, and pipe length.
Lawn Area
sq ft
Rectangle
Scenario: You're irrigating a rectangular 4,200 sq ft front yard with clean property lines.
Result: Spray heads: 6 (at 700 sq ft each). Total GPM: 12. Zones: 1 (fits within 12 GPM). Pipe estimate: 130 linear ft.
Irregular
Scenario: Your backyard is an irregular shape and you've estimated the total area at 3,000 sq ft.
Result: Spray heads: 5 (at 700 sq ft each). Total GPM: 10. Zones: 1. Pipe estimate: 110 linear ft. For irregular shapes, plan extra heads near tight corners for full coverage.
Divide your lawn area by the coverage per head. Standard spray heads cover about 700 sq ft each (15 ft radius). Rotor heads cover about 3,800 sq ft each (35 ft radius). Use spray heads for small areas and rotors for large open lawns.
Most residential water supplies deliver about 12 GPM. Each spray head uses about 2 GPM, so you can run 5-6 heads per zone. Divide your total heads by 5-6 to get your zone count.
Main lines: 8-12 inches. Laterals: 6-8 inches. In cold climates, go below the frost line or plan on blowing out the system every fall.
DIY installation costs $500-$1,500 for a half-acre yard. Professional installation runs $2,500-$5,000+. The cost breaks down to: controller ($50-$200), valves ($15-$30 each), heads ($5-$15 each), and pipe ($0.30-$0.50 per foot). The controller and valves are the expensive parts, not the pipe and heads.
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