Growing Degree Days Calculator
Heat accumulation used to time planting and harvest.
°C
°C
°C
How it 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.
FAQ
Is this calculator free?
Yes. No signup is needed and nothing you enter is stored.
Is the result exact?
Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.
Do my numbers leave my device?
No. The calculation runs in your browser.