Irrigation System Calculator
Calculate drip and sprinkler flow rates, zone coverage, and run times.
Size pipes, emitters, and zones for efficient crop and garden irrigation requirements.
Crop Water Requirement ETc = ETo × Kc Where: ETc = crop evapotranspiration (mm/day) ETo = reference evapotranspiration (mm/day) — depends on climate Kc = crop coefficient (dimensionless) — varies by crop and growth stage
Common ETo Values by Climate (mm/day) Arid (desert): 6–9 Semi-arid: 4–6 Temperate: 2–4 Humid / tropical: 2–5 (varies seasonally) Actual ETo from your local weather station is always most accurate.
Drip Irrigation Flow rate per emitter: Q_emitter (L/h) Total flow per zone: Q_zone = N_emitters × Q_emitter (L/h) Application rate: AR = Q_zone (L/h) / Area (m²) × 1000 → mm/h Runtime: T = ETc / AR × 60 (minutes)
Sprinkler Irrigation Application rate: AR = Q_total (L/h) / Area (m²) × 1000 → mm/h Sprinkler spacing affects uniformity — triangular spacing is most efficient. Distribution uniformity (DU) target: > 80%
Pipe Sizing Velocity in pipe: V = Q / A = Q / (π × d² / 4) Recommended velocity: < 1.5 m/s to avoid pressure loss and noise. Friction loss (Hazen-Williams): hf = 10.67 × L × Q^1.852 / (C^1.852 × d^4.87)
Irrigation Efficiency Surface (furrow): 40–60% Sprinkler: 70–85% Drip/micro: 85–95% Net requirement = Gross requirement × efficiency