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Sprinkler Coverage Calculator — Even Lawn Watering
Work out sprinkler placement and overlap for even lawn coverage.
How We Calculate This
Effective coverage = Sprinkler coverage area × overlap factor (default 0.75, i.e. a 25% overlap allowance).
Sprinklers needed = Lawn area ÷ Effective coverage per sprinkler, rounded up.
Typical full-circle coverage at good mains pressure (~2-3 bar): oscillating ~200 m², gear-drive rotor ~300 m², fixed-spray pop-up ~65 m² (15 ft / 4.6 m radius), impulse ~500 m². Part-circle patterns or low pressure cover less, so size up if in doubt.
The 0.75 default suits portable, moving garden sprinklers (oscillating, impulse) where the spray sweeps the lawn. For a permanent fixed-head system using professional head-to-head spacing — each head reaching its neighbour, one radius apart — overlap is far heavier: drop the overlap factor to around 0.3-0.5 to get a realistic (higher) head count.
Frequently Asked Questions
Sprinklers should overlap by about 25% for even coverage. Without overlap, you get dry patches between sprinkler zones.
Oscillating sprinklers are best for rectangular lawns. Pop-up sprinklers suit smaller areas. Rotary sprinklers are good for medium lawns.
Place a tuna tin on the lawn and time how long it takes to fill 25mm. That is your weekly watering time, split into 2-3 sessions.
Usually yes, but hosepipe bans may restrict use during drought. Check your water company for current restrictions.
For a permanent fixed-head system, the industry standard (Rain Bird, the Irrigation Association) is head-to-head spacing: each sprinkler is placed so its spray reaches the next head — heads sit about one radius apart (50% of the throw diameter) on a square grid, or about 60% on a triangular grid. That is much heavier overlap than the 0.75 default here, so for a designed fixed system lower the Overlap Factor to roughly 0.3-0.5 to get a realistic head count. The 0.75 default is aimed at portable sprinklers you move around the lawn.
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.