Growing Degree Days Calculator
Fill in the values and the answer updates as you type.
How the Growing Degree Days Calculator works
Growing degree days (GDD) per day = (daily high + daily low) ÷ 2 − base temperature, never below zero. Crops and insects need a set number of GDD to reach each growth stage, and a base of 10 °C suits many warm-season crops. This uses the simple average method with constant temperatures. Example: with the default values, each day adds 11 GDD, or 990 over 90 days.
Inputs and results
The Growing Degree Days Calculator takes 4 inputs and gives 2 results.
What you enter
- Daily high (°C) — starts at 28.
- Daily low (°C) — starts at 14.
- Base temperature (°C) — starts at 10.
- Number of days — starts at 90.
What you get
- Degree days per day
- Total over the period
Example: Growing Degree Days Calculator with the starting values
With daily high 28 °C, daily low 14 °C, base temperature 10 °C and number of days 90, the calculator returns:
| Degree days per day | 11 |
|---|---|
| Total over the period | 990 |
Change any value above and the results update straight away.
Growing Degree Days Calculator FAQ
How do I use the Growing Degree Days Calculator?
Enter daily high, daily low, base temperature and number of days in the fields, then read degree days per day and total over the period in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Growing Degree Days Calculator calculate?
Heat accumulation used to time planting and harvest. It returns degree days per day and total over the period from the 4 values you provide.
What values does the Growing Degree Days Calculator start with?
It opens with daily high 28 °C, daily low 14 °C, base temperature 10 °C and number of days 90 so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Growing Degree Days Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Growing Degree Days Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.