How it works
- 1Enter the requested values.
- 2Choose the units or calculation options that match your data.
- 3Calculate and review the result and assumptions.
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ET₀ Calculator – FAO56
Estimate daily reference evapotranspiration with the FAO-56 Penman–Monteith equation using temperature, humidity, radiation, wind and elevation.
✓ Local browser calculation✓ Agricultural units and formula-aware validation✓ Responsive results for desktop and mobile
Inputs
Results
Reference ET₀
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Mean temperature
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Saturation vapor pressure (es)
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Actual vapor pressure (ea)
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Vapor pressure deficit
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Calculation aid only: verify units, product labels, laboratory/soil-test results and local agronomic recommendations before field use.
About this tool
Estimate daily reference evapotranspiration with the FAO-56 Penman–Monteith equation using temperature, humidity, radiation, wind and elevation.
Common uses
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Frequently asked questions
Does this calculator upload my data?
No. The calculation runs locally in your browser.
Should I treat the result as an agronomic recommendation?
No. It is a calculation aid. Product labels, soil/lab results, crop requirements and local regulations or extension recommendations remain authoritative.