Free irrigation scheduling calculator. Determine when and how much to irrigate based on soil type, crop water requirements (ETc), root zone depth, and irrigation method efficiency.
Ideal soil with excellent water retention and drainage balance.
AWC: 2 in/ft | Infiltration: 0.5 in/hr
Water delivered directly to root zone through emitters.
Efficiency: 90% | Best for: Row crops, Orchards, Vineyards
You might also find these calculators useful
Calculate irrigation runtime, emitters needed, and water volume
Calculate reference ET and crop water needs using FAO Penman-Monteith
Calculate irrigation water needs using FAO Penman-Monteith
Calculate rainwater collection potential from your roof
Proper irrigation scheduling maximizes crop yield while conserving water. Our calculator uses soil water balance principles to determine optimal irrigation frequency, duration, and application amounts based on your soil type, crop characteristics, and irrigation system efficiency. Get a 7-day schedule preview and monthly water use estimates.
Irrigation scheduling determines WHEN to irrigate and HOW MUCH water to apply. It's based on the soil water balance concept: tracking how much water is available in the root zone, how fast crops use it (ETc), and when to replenish before plants experience stress. The key is timing irrigation before the Readily Available Water (RAW) is depleted.
Irrigation Interval Formula
Interval (days) = (AWC × Root Depth × MAD) ÷ ETcApply only what plants need, when they need it. Avoid overwatering that wastes water and leaches nutrients.
Prevent water stress that reduces yields. Avoid waterlogging that damages roots and promotes disease.
Reduce pumping costs by eliminating unnecessary irrigation cycles and optimizing application amounts.
Proper scheduling reduces nutrient leaching and improves fertilizer efficiency.
Determine optimal sprinkler runtime and frequency for healthy turf and vegetables.
Schedule field irrigation for row crops, orchards, and vineyards to maximize water efficiency.
Plan drip irrigation cycles for container and bench crops with high precision.
Create efficient irrigation schedules for parks, golf courses, and commercial landscapes.
ETc (Crop Evapotranspiration) is the daily water use by your specific crop, measured in inches or mm per day. Get it from local weather stations, agricultural extension services, or use our Evapotranspiration Calculator. Typical values: lawns 0.15-0.25 in/day, vegetables 0.20-0.35 in/day, mature orchards 0.25-0.40 in/day during peak season.
MAD is the percentage of soil water that can be depleted before irrigation is needed. For stress-sensitive crops (vegetables, turf), use 40-50%. For moderate crops (corn, orchards), use 50-60%. For drought-tolerant crops (alfalfa, grapes), 60% or higher may be acceptable. Lower MAD means more frequent irrigation but less stress risk.
Different soils hold different amounts of water. Sandy soils drain quickly (low AWC: 0.75-1.0 in/ft) requiring more frequent irrigation. Clay soils hold more water (AWC: 1.5-2.0 in/ft) but have slow infiltration rates—apply water slowly to prevent runoff. Loam soils are ideal with moderate retention and infiltration.
Efficiency determines how much water actually reaches plant roots. Drip (90%+) and subsurface drip (95%+) are most efficient. Sprinklers lose water to evaporation and wind (70-85% efficiency). Surface irrigation is least efficient (50-65%). Lower efficiency means applying more water to deliver the same net amount to roots.
Yes! ETc increases significantly during hot, dry, and windy conditions. A lawn using 0.15 in/day in spring may use 0.30 in/day in summer heat. Adjust your schedule based on current weather. Many irrigators use local ET data services or smart controllers that automatically adjust for weather.