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Irrigation & Water
Use Calculator Irrigation Water Requirement Calculator
Estimate net and gross irrigation depth and total water volume after rainfall and system-efficiency adjustments.
Irrigation & Water Calculators
Crop Water Need Calculator
Calculate crop evapotranspiration and field water volume from reference evapotranspiration and crop coefficient.
Free agriculture calculator
No signup requiredCrop Water Need Calculator
Your results
How to use the Crop Water Need Calculator
- Enter the requested field, crop, animal, equipment, or cost information.
- Keep every value in the unit shown beside its field.
- Select Calculate and review each result and assumption.
- Verify important decisions with local records, labels, extension guidance, or a qualified adviser.
Formula and method
Crop evapotranspiration (ETc) = ETo × Kc. Water volume (m³) = ETc × days × area (ha) × 10.
The FAO single-crop-coefficient approach scales reference evapotranspiration to the selected crop and growth stage.
Worked example
At ETo 5 mm/day and Kc 1.1, ETc is 5.5 mm/day; five hectares require 1,925 m³ over seven days.
Understanding the result
Treat the calculated values as a planning estimate. Compare them with your field records, product information, local conditions and operational capacity before acting.
Important: Use locally appropriate ETo and Kc values. Crop stage, climate and management can materially change water need.
Frequently asked questions
What does the Crop Water Need Calculator calculate?
Calculate crop evapotranspiration and field water volume from reference evapotranspiration and crop coefficient.
How accurate is this calculator?
The arithmetic follows the formula shown, but the practical accuracy depends on your measurements, assumptions and local conditions.
Can I use the result for a final farm decision?
Use it for planning and comparison. Verify high-impact crop, chemical, engineering, financial or animal decisions with current local guidance and qualified advice.
Does BlogAgri store my calculator inputs?
No. The calculator runs in your browser and does not submit the entered values to BlogAgri.
