Growing Degree Days Calculator — GDD from Daily Temperatures
Calculate Growing Degree Days (GDD) for a single day from the daily high and low temperature and a base temperature. The standard averaging method is used: GDD = ((Tmax + Tmin)/2) − Tbase, with a floor of zero. Enter the base temperature appropriate for your crop — there is no universal base.
What this calculator determines
It calculates Growing Degree Days for a single day from the daily high and low temperatures and a base temperature you choose.
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Examples
High 82°F, low 60°F, base 50°F
Tmax 82, Tmin 60, Tbase 50
Calculation
- Average: (82 + 60) / 2 = 71
- GDD: 71 − 50 = 21
21 GDD
Assumptions & Conventions
- Formula
- Uses the standard averaging method: GDD = max(0, ((Tmax + Tmin) / 2) − Tbase). It does not cap Tmax or use a single-sine curve.
- Base temperature
- Base temperature depends on the crop — use the base recommended for your specific crop; there is no universal base.
- Single day
- Computes GDD for one day; sum daily values over a period for accumulated GDD.