Irrigation Design Calculator
Plan your irrigation system from scratch. Select your head type, enter your lawn or garden dimensions, and get the number of heads, zones, pipe length, and total materials cost.
Choosing Between Rotary, Spray, and Drip
Rotary heads throw water 25 to 50 feet and are ideal for large open lawns. They apply water slowly and uniformly, reducing runoff. Spray heads cover 5 to 15 feet and work best in smaller lawn areas, narrow strips, and tight spaces. They apply water faster, so shorter run times are needed. Drip irrigation delivers water directly to the root zone through emitters and is the most efficient option for garden beds, shrubs, trees, and containers. Most properties use a combination of all three types, separated into different zones.
Zone Design Principles
Group heads by type: never mix rotary and spray heads on the same zone, as their precipitation rates differ dramatically. Group by sun exposure, since sunny areas need more water than shady ones. Match heads to the available flow rate so each zone stays within your supply capacity. Position heads for head-to-head coverage, meaning each head throws water all the way to its nearest neighbor. This overlap ensures even distribution and prevents dry spots.
Frequently Asked Questions
How many sprinkler heads per zone?
It depends on your flow rate and head GPM. Typically 3 to 4 rotary heads or 6 to 8 spray heads per zone at 12 GPM. Never exceed your available flow rate per zone.
What size pipe for residential irrigation?
Use 3/4-inch or 1-inch PVC mainline from the water source to the valves. Use 3/4-inch poly or PVC for lateral lines running to heads. Larger properties may need 1-1/4-inch mainline.
How do I find my water flow rate?
Fill a 5-gallon bucket from your outdoor spigot and time it. Divide 5 by the seconds, then multiply by 60 to get gallons per minute. Most residential systems deliver 8 to 15 GPM.