Compare calculators
Both calculators run independently — change the inputs on either side to compare results.
Climate
Evapotranspiration Calculator
Estimate monthly potential evapotranspiration (PET) from average temperature, daylight hours, and days in the month using a simplified Thornthwaite-style formula. Returns millimetres of water lost per month.
Fill in the required fields to see your result.
Climate
Solar Radiation Calculator
Estimate top-of-atmosphere solar irradiance at solar noon for a given latitude, day of year, and solar declination. Returns watts per square metre on a horizontal surface, before atmospheric attenuation.
Fill in the required fields to see your result.
Key differences
| Evapotranspiration Calculator | Solar Radiation Calculator | |
|---|---|---|
| Category | Climate | Climate |
| Inputs required | 3 | 3 |
| Result | Potential Evapotranspiration (mm/month) | Solar Radiation (W/m²) |
| What it does | Estimate monthly potential evapotranspiration (PET) from average temperature, daylight hours, and days in the month using a simplified Thornthwaite-style formula. Returns millimetres of water lost per month. | Estimate top-of-atmosphere solar irradiance at solar noon for a given latitude, day of year, and solar declination. Returns watts per square metre on a horizontal surface, before atmospheric attenuation. |