Estimate growing degree days from daily high temperature, daily low temperature, base temperature, upper cutoff, crop type, and number of days. This calculator is useful for gardening, farming, pest tracking, planting schedules, and crop development estimates.
High and low temperature:
Enter the daily maximum and minimum temperature for the period you want to estimate.
Base temperature:
The base temperature is the lower threshold where crop or insect development is assumed to begin.
Upper cutoff:
The upper cutoff limits hot temperatures because development often does not keep increasing above a certain point.
Accumulated GDD:
The calculator can add previous GDD and compare your total against a target heat-unit goal.
A growing degree days calculator is useful for estimating crop development, planting timing, pest emergence, flowering windows, harvest planning, garden tracking, turf management, and comparing seasonal heat accumulation.
This is a rough planning calculator. Actual plant growth depends on crop variety, soil temperature, soil moisture, sunlight, fertility, stress, pests, disease, and local agronomic models.
Your result shows estimated growing degree days for one day, the selected number of days, and the total after adding any previous accumulated GDD. Higher GDD values mean more heat units have accumulated for crop or pest development.
Average the daily high and low temperature, then subtract the base temperature. If the result is below zero, daily GDD is usually counted as zero.
It depends on the crop, plant, or insect being tracked. A 50°F base is common for corn and several warm-season crops, while cool-season crops may use a lower base.
In most growing degree day tracking, negative values are set to zero because cold days do not subtract from accumulated heat units.
An upper cutoff limits the temperature used in the GDD formula so very hot days do not add excessive heat units beyond the crop or pest development range.