Quickly convert ET data into liters today. Choose plant count, area, and system efficiency easily. Download results for records, sharing, and better planning later.
| Scenario | ET0 (mm/day) | Kc | Area (m2) | Eff. (%) | Gross (L/day) | Gross (L/event) |
|---|---|---|---|---|---|---|
| Summer vegetables, drip | 6.0 | 1.05 | 12 | 85 | ~88.9 | ~88.9 |
| Herbs, partial shade | 4.5 | 0.70 | 8 | 80 | ~31.5 | ~63.0 (every 2 days) |
| Shrubs, windy site | 5.5 | 0.85 | 20 | 75 | ~124.7 | ~124.7 |
Tip: If plants wilt midday, reduce interval or improve microclimate factor accuracy.
Reference ET0 represents the atmospheric demand for water from a well-watered surface. When ET0 rises due to sun, wind, or low humidity, plant water use increases even if soil moisture is adequate. Using daily ET0 or a weekly average improves repeatability. In gardens, station values can differ from shaded courtyards, so validate with local posture and soil feel.
The plant coefficient Kc scales ET0 to match canopy type and growth stage. Young transplants and sparse canopies typically use lower Kc values, while dense vegetables, turf, or vigorous vines use higher values. The microclimate factor refines exposure effects such as reflected heat near walls, wind, or deep shade. Together, ETc = ET0 × Kc × microclimate provides a defensible demand estimate.
Effective rainfall is the portion that actually infiltrates and stays within the root zone. Short storms on dry mulch may contribute less than measured rain, while slow soaking events can contribute more. After net demand is found, irrigation efficiency converts it to the applied gross volume, accounting for drift, evaporation, runoff, and distribution losses. Improving uniformity saves more water than reducing runtime.
Soil available water capacity and root depth define how much water can be stored between irrigations. Total available soil water is AWC × root depth, and the allowable depletion percentage sets the portion plants can use before stress begins. The calculator’s suggested maximum interval compares that readily available water against ETc. Use shorter intervals for containers, sandy soils, and sensitive crops.
When using drip, total emitter count and flow rate convert event liters into an estimated runtime per watering. This supports consistent scheduling across beds, orchards, and mixed plantings. For per-plant targets, enter plant count to view liters per plant per day and per event. Recheck coefficients after pruning, canopy expansion, or seasonal shifts to keep demand aligned.
Start with 0.4 to 0.7 for young plants, 0.8 to 1.1 for dense summer vegetables, and 0.6 to 0.9 for shrubs. Adjust after observing growth, wilting, and soil moisture patterns.
Use a conservative fraction of measured rain unless the event was slow and soaking. Sandy soils drain quickly, while mulched beds store more. If water ran off, count less as effective.
Net demand is what roots need. Gross demand includes losses from distribution and evaporation. Lower efficiency requires more applied water to deliver the same net amount to the root zone.
It is a planning estimate based on soil storage and ETc. Use it as an upper limit, then refine with local observations, container size, soil texture, and crop sensitivity during heat waves.
Yes, but reduce root depth and allowable depletion because storage is smaller. Containers often need shorter intervals, especially in wind. Verify by checking moisture a few centimeters below the surface.
Yes. Update Kc and microclimate as canopy expands, pruning occurs, or weather shifts. Revisit efficiency after maintenance. Seasonal recalibration keeps liters per day aligned with real plant demand.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.