Evaporation Pan ET₀ Calculator
Convert Class-A evaporation-pan readings into reference ET₀ using a pan coefficient.
ET₀ = Kp × Epan. The pan coefficient Kp (typically 0.6–0.85) depends on pan siting, humidity and wind; 0.7 is a common default for a Class-A pan in a cropped, moderate-wind setting.
Indicative planning figures based on published research averages. Local soil tests, varieties and weather change actual requirements — confirm with your agronomist or extension officer.
Farmers and irrigation engineers use the free Evaporation Pan ET₀ Calculator to get an accurate answer in seconds — no formulas to remember, works offline in the field.
About Evaporation Pan ET₀ Calculator
Many research farms and irrigation departments still measure evaporation with a Class-A pan — a simple, robust way to gauge atmospheric water demand. To turn a pan reading into reference ET₀ you apply a pan coefficient (Kp) that corrects for the pan's tendency to over-read because of heat stored in its metal and water. This tool multiplies your pan evaporation by Kp to give ET₀ in mm/day and per month, ready to combine with crop coefficients for scheduling.
How to use Evaporation Pan ET₀ Calculator
- 1Enter your system or field values into the inputs.
- 2Read the headline result and the supporting breakdown.
- 3Apply the guidance in the note to your irrigation plan.
Why use Evaporation Pan ET₀ Calculator?
- ✓Uses the standard, citable irrigation engineering formula
- ✓Clear inputs with sensible defaults
- ✓Instant result with the working shown
- ✓Free, fully in-browser and private
Frequently asked questions
How do I convert pan evaporation to ET₀?+
Multiply the daily pan evaporation by the pan coefficient: ET₀ = Kp × Epan. A Class-A pan reading of 8 mm/day with Kp = 0.7 gives ET₀ of 5.6 mm/day. The pan over-reads, so Kp is always less than 1.
What pan coefficient (Kp) should I use?+
Kp typically ranges 0.6–0.85 depending on the pan's surroundings, humidity and wind. A pan in a green, cropped area with moderate wind and humidity is around 0.7–0.8; a pan on dry, windy fallow reads higher and needs a lower Kp (~0.6).
Is this tool free and private?+
Yes — free, no sign-up, and all calculation runs in your browser, so it works offline and your data never leaves the device.
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