GDU / GDD Calculator
Track the real biological timeline of your crops. Enter the daily high and low temperatures to see how many heat units were added to your season's total.
e.g., 50 for corn
What are Growing Degree Units (GDU)?
Growing Degree Units (also called Growing Degree Days or GDD) is a measure of heat accumulation used by farmers and horticulturists to predict plant and insect development rates, such as the date a crop will reach maturity.
How is GDU calculated?
The basic formula is GDU = ((Max Temp + Min Temp) / 2) - Base Temp. If the daily average temperature is below the base temperature, the GDU for that day is zero.
What is the "Base Temperature"?
The base temperature is the threshold below which a specific plant or insect species does not grow. For corn, the standard base temperature is 50°F (10°C).
Why are GDUs better than counting days?
Plants grow based on heat, not just time. A cool week might see very little development, while a hot week sees rapid growth. GDUs provide a more accurate biological timeline than simple calendar days.