Growing Degree Day (GDD) Calculator
Calculate daily growing degree days (GDD) for agriculture, pest management, and plant phenology studies. Essential for predicting crop development and insect life cycles.
Degree-Day Calculator (GDD)
basicCalculate growing degree days for plant and insect development
Formula
GDD = ((Tmax+Tmin)/2) - Tbase
How It Works
Growing Degree Days (GDD) measure heat accumulation above a threshold temperature. The formula uses the average daily temperature minus a base temperature (below which development stops).
GDD = max(0, ((Tmax + Tmin)/2) − Tbase)
If the average temperature is below the base, GDD = 0 for that day.
Example
A day with Tmax=25°C, Tmin=12°C, and base temperature 10°C (e.g., for corn):
Avg Temp = (25 + 12)/2 = 18.5°C
GDD = 18.5 − 10 = 8.5
Corn needs ~2800 GDD (base 10°C) to reach maturity. Insect pests like codling moth use base 10°C with ~600-1000 GDD per generation.
Frequently Asked Questions
What base temperature should I use?
Base temperature varies by organism: Corn 10°C, Wheat 0°C, Tomato 10°C, Pea 4.4°C, Codling moth 10°C, Soybean 10°C. Research the specific base for your crop or pest.
How do I calculate cumulative GDD?
Sum daily GDD values over the growing season starting from a biofix date (e.g., planting date or first pest capture). Cumulative GDD is used to predict crop maturity stages and pest emergence.
What is the difference between GDD and degree-days?
Growing Degree Days (GDD) are specifically for plant and insect development with a base temperature. Degree-days can use different calculation methods (sine wave, modified) and can also represent heating/cooling needs in buildings.