What this calculator does
Growing degree units (GDU) works out accumulated heat units driving crop development, from daily high/low temperature and a base. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Average daily high temperature (°C) | A number, measured in °C. Starts at 25. |
| Average daily low temperature (°C) | A number, measured in °C. Starts at 15. |
| Base temperature (crop threshold) (°C) | A number, measured in °C. Starts at 10. |
| Number of days | A number. Starts at 30. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with average daily high temperature
Every other input is held at the calculator’s starting values while average daily high temperature varies. Select any row to load that scenario into the calculator.
| Average daily high temperature (°C) | Accumulated GDU over 30 days | Daily GDU | Average daily mean temperature |
|---|---|---|---|
| 12.5 | 112.5 GDU | 3.75 GDU/day | 13.75 °C |
| 18.75 | 206.3 GDU | 6.88 GDU/day | 16.88 °C |
| 25 | 300.0 GDU | 10.00 GDU/day | 20.00 °C |
| 37.5 | 487.5 GDU | 16.25 GDU/day | 26.25 °C |
| 50 | 675.0 GDU | 22.50 GDU/day | 32.50 °C |
| 75 | 1,050.0 GDU | 35.00 GDU/day | 45.00 °C |