How to use the growing degree days calculator
Find the daily heat units a crop accumulates above a base temperature. Enter daily maximum, daily minimum, base temperature in the fields above; the growing degree days for one day, fahrenheit equivalent are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “growing degree days”, “crop heat units”, “GDD for planting”, “calculate growing degree days”, “find growing degree days for one day”.
Formula
Variables
- tmax — Daily maximum (°C)
- tmin — Daily minimum (°C)
- tb — Base temperature (°C)
Worked example
With daily maximum = 28 °C, daily minimum = 14 °C, base temperature = 10 °C, the calculator gives growing degree days for one day ≈ 11 °C·day; fahrenheit equivalent ≈ 19.8 °F·day.
Frequently asked questions
What is the growing degree days calculator used for?
Find the daily heat units a crop accumulates above a base temperature. It helps with questions such as “growing degree days”, “crop heat units”, “GDD for planting”.
What is the formula for the growing degree days calculation?
Growing degree days for one day (°C·day) = max((tmax+tmin) / 2-tb,0). Fahrenheit equivalent (°F·day) = [Growing degree days for one day] × 1.8. Here tmax is daily maximum (°C), tmin is daily minimum (°C), tb is base temperature (°C).
What inputs do I need for the growing degree days calculator?
You need daily maximum in °C, daily minimum in °C, base temperature in °C. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the growing degree days calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the growing degree days result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.