Formula Used
Water volume: Area × Watering depth.
Imperial water: ft² × inches × 0.623 gallons.
Crop demand: ETc = ET0 × Kc.
Gross requirement: Net requirement ÷ Irrigation efficiency.
Runtime: Required volume ÷ Actual operating flow.
Total drip flow: Emitters × Flow per emitter.
The calculator converts every measurement into consistent base units. It then applies rainfall and irrigation efficiency. Final values return in your selected output unit.
How to Use
Select one area or choose multiple irrigation zones. Enter crop, soil, climate, and watering information. Then describe system flow and available supply capacity.
Choose schedule limits, output units, and operating prices. Submit the form to calculate demand and runtime. Review warnings before applying the recommended irrigation plan.
Use cycle-and-soak for slowly absorbing soils. Compare demand against tank and pump capacities. Export the results for records or field planning.
Example Data
| Example | Area | Method | Depth | Efficiency | Approximate gross water |
|---|---|---|---|---|---|
| Small lawn | 100 m² | Sprinkler | 20 mm | 75% | 2,667 L |
| Vegetable beds | 80 m² | Drip | 18 mm | 90% | 1,600 L |
| Orchard block | 0.5 acre | Micro-sprinkler | 25 mm | 85% | 59.51 m³ |
Frequently Asked Questions
What does irrigation efficiency mean?
Efficiency measures water reaching the crop root zone. Lower efficiency increases required gross water volume. Field conditions can change the practical efficiency.
How is effective rainfall calculated?
Expected rainfall is multiplied by its usable percentage. Runoff and deep drainage reduce effective rainfall. Local soil conditions influence the final percentage.
Which irrigation method saves most water?
Well-designed drip systems often achieve high efficiency. Maintenance and pressure control remain very important. Actual savings depend on crop and management.
Why can runtime differ between zones?
Zones may have different areas and device flows. Crop coefficients can also change water demand. Separate scheduling improves control and uniformity.
What is cycle-and-soak irrigation?
Watering is divided into shorter application cycles. Rest periods allow water to infiltrate soil. This method reduces runoff on compacted ground.
Can the calculator handle acres?
Yes, direct areas and zones support acres. The calculator converts acres into square metres. Results can display litres or gallons.
How should rainfall be entered?
Enter rainfall expected during the planning period. Use the same selected depth unit. Adjust the effective percentage for local losses.
What happens when supply flow is limited?
The calculator limits operating flow to system capacity. Lower flow increases the required irrigation runtime. Divide large systems into smaller zones.
Does pressure affect sprinkler performance?
Yes, pressure changes flow and coverage patterns. Insufficient pressure may create dry areas. Excess pressure can increase misting and losses.
Are cost estimates exact?
Costs use entered water and energy prices. Tariffs and pump efficiency can vary. Treat calculated costs as planning estimates only.
Can results be saved?
Use copy, CSV, PDF, or print controls. Exports include the main calculation results. Keep records for seasonal irrigation comparisons.