Sprinkler Heads Needed
1
Zones
1
Total GPM
3
Weekly Gal
935
Range: 25–45 ft for Rotor
Sprinkler Heads Needed
1
Rotor heads
Zones
1
Total GPM
3
Inputs
Result
Coverage = π × 35² = 3,848 sq ft. Effective = 3,848 × 0.5 = 1,924 sq ft. Heads = ceil(1,500/1,924) = 1. GPM = 1 × 3.0 = 3.0. Zones = 1. Weekly = 1,500 × 0.623 = 935 gal.
Inputs
Result
Coverage = π × 12² = 452 sq ft. Effective = 452 × 0.5 = 226 sq ft. Heads = ceil(800/226) = 4. GPM = 4 × 1.5 = 6.0. Zones = 1.
Inputs
Result
Coverage = π × 30² = 2,827 sq ft. Effective = 2,827 × 0.5 = 1,414 sq ft. Heads = ceil(5,000/1,414) = 4. GPM = 4 × 4.0 = 16.0. Zones = ceil(16/15) = 2.
The number of sprinkler heads depends on your lawn size, head type, and overlap. For a 1,500 sq ft lawn using rotor heads with 35 ft radius and 50% overlap, you need about 3–4 heads. Spray heads with 12 ft radius need 10–12 heads for the same area.
| Head Type | Radius | Coverage/Head | Heads for 1,500 sq ft |
|---|---|---|---|
| Rotor | 25–45 ft | ~3,850 sq ft | 3–4 |
| Spray | 8–15 ft | ~450 sq ft | 10–12 |
| Impact | 20–40 ft | ~2,830 sq ft | 4–5 |
| Drip | 1–3 ft | ~12 sq ft | N/A (beds only) |
Most residential sprinkler systems need 30–50 PSI at the sprinkler head. Spray heads work at 15–30 PSI, rotors need 30–45 PSI, and impact heads need 35–50 PSI. Low pressure below 30 PSI causes poor spray patterns and dry spots.
Head-to-head coverage means each sprinkler head's spray reaches the next head. If heads throw 30 ft, they're spaced 30 ft apart. This creates 50% overlap in the middle, ensuring no dry spots. It's the standard design principle for uniform irrigation.
Zones are determined by your water supply flow rate (GPM). A typical home water supply delivers 10–15 GPM. If your total head GPM exceeds this, split into zones. For example, 8 rotor heads at 3 GPM each = 24 GPM total, requiring 2 zones at 12 GPM each.
| Total GPM | Available Supply | Zones Needed | Heads/Zone (rotors) |
|---|---|---|---|
| 9 GPM | 15 GPM | 1 | 3 rotors |
| 18 GPM | 15 GPM | 2 | 3 rotors each |
| 30 GPM | 15 GPM | 2–3 | 3–4 rotors each |
| 45 GPM | 15 GPM | 3–4 | 3–4 rotors each |
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Last Updated: Mar 9, 2026
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