Growing Degree Days
Track heat accumulation to time crop growth and pests.
About Growing Degree Days
Each day's average temperature above the base contributes heat units, totaled over the growing period. Plants develop on accumulated heat rather than calendar days, so GDD predicts bloom, fruit and pest risk.
Formula
Growing Degree Days
Daily GDD = (high + low)/2 - base, floored at 0
- base temp
- Temperature below which the crop develops little or none
Worked example
With the default values below, Growing Degree Days returns Daily GDD of 15.0. Change any input above and every figure here is recalculated in your browser.
Inputs used
- High tempminimum 0 F
- 75 F
- Low tempminimum 0 F
- 55 F
- Base tempminimum 0 F
- 50 F
- Days countedminimum 1
- 30
Results
- Daily GDD
- 15.0
- Total GDD
- 450
- Weekly GDD
- 105.0
Step by step
- 1Values used
- 2Growing Degree Days
- 3Daily GDD= 15.0
- 4Total GDD= 450
- 5Weekly GDD= 105.0
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Growing Degree Days calculated?
Daily GDD = (high + low)/2 - base, floored at 0 Each day's average temperature above the base contributes heat units, totaled over the growing period.
Why does Growing Degree Days matter?
Plants develop on accumulated heat rather than calendar days, so GDD predicts bloom, fruit and pest risk.
What values do I need to enter?
This calculator takes 4 inputs: High temp, Low temp, Base temp, Days counted. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.