Calculate one day's growing degree units from the daily high, low, and crop base temperature.
| GDU | – |
Use this calculator for a single day's heat units (GDU or GDD). Farmers add these through the season to estimate when corn, wheat, or a vegetable will reach a growth stage. Sum the daily results yourself across a weather log.
The calculation is: GDU = max(0, (Tmax capped + Tmin) ÷ 2 − Tbase). Daily maximum temperature is capped at 30 °C (86 °F) before averaging, which matches the common modified corn method. A day whose mean is at or below the base contributes zero. Temperatures can be entered in °C or °F; they are converted to Celsius before the calculation. The result is in Celsius degree-days.
This page does not floor the daily minimum at the base, and it does not accumulate a season total. Choose a base that matches the crop (often 10 °C / 50 °F for maize).
Daily maximum: The day's highest air temperature, in °C or °F.
Daily minimum: The day's lowest air temperature, in °C or °F.
Base temperature: The crop base. Below this, growth is treated as zero. Maize is often 10 °C.
GDU: Growing degree units for that day, in °C·day.
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