Irrigation System Calculator
Calculate drip and sprinkler irrigation flow rates, zone coverage, run times, and water requirements.
Size pipes, emitters, and zones for efficient crop and garden irrigation.
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