🌡️ GDU Calculator
Track crop development progress by converting temperature data into growing degree units.
Corn uses 50°F; adjust for other crops.
Temperatures above this value are capped.
Optional starting point from previous days or growing season.
How to Use This Calculator
Collect daily high and low temperatures
Use nearby weather station data or on-farm sensors.
Select crop-specific thresholds
Most corn uses 50°F base and 86°F ceiling; other crops vary.
Track cumulative GDUs
Add daily GDUs to monitor growth stages and schedule management tasks.
Formula
Daily GDU = max(0, [(Tmax + Tmin) ÷ 2] − Base)
Clamp Tmax to the upper cutoff and Tmin to the base.
GDUs accumulate over the season to predict phenological stages such as silking, maturity, or harvest readiness.
Full Description
Growing degree units model crop development based on heat accumulation. Scheduling irrigation, fertilizer, or pest scouting by GDU milestones improves efficiency and reduces risk.
Local extension services publish GDU targets for hybrid maturity groups; consult these resources for precise management timing.
Frequently Asked Questions
What base temperature should I use?
Corn typically uses 50°F. Cool-season crops may use 40°F, while warm-season vegetables often use 60°F.
Why cap high temperatures?
Temperatures above the upper cutoff provide diminishing returns, so they are capped to reduce overestimation.
Can I use Celsius?
Convert temperatures to Fahrenheit first or adapt the formula to Celsius using appropriate base values.
How do I calculate GDUs for missing days?
Use historical weather data or station averages to fill gaps and maintain accuracy.