Work out sprinkler coverage instantly with clear inputs, formula shown and shareable results.
A rotating sprinkler wets a circle, but heads must overlap to give even coverage — spacing is set at 50-60% of the wetted diameter, so each head is credited with a square of side (2 x radius x spacing factor). Application rate is nozzle flow divided by that square, in mm/hour, and must stay below the soil infiltration rate to avoid runoff.
Spacing and coverage
Spacing = 2 x radius x spacing%; area per head = spacing^2
Application rate
Rate (mm/h) = flow (L/min) x 60 / area per head (m2)
A single sprinkler applies far less water at the edge of its circle than near the head. Overlapping at 50-60% of diameter evens out the profile; wider spacing leaves dry rings between heads.
Keep it under the soil intake rate — roughly 25-50 mm/h for sand, 10-20 mm/h for loam and 4-10 mm/h for clay. Above that, water ponds and runs off instead of infiltrating.