Growing Degree Day Calculator
Track heat unit accumulation for corn, soybeans, and wheat. Enter your accumulated GDD and current temperatures to predict days to the next growth stage.
Find this from your county extension office, local co-op, or state ag weather network.
Today's Temperatures (°F)
Current Crop Status
0
accumulated GDD
Enter accumulated GDD to see current stage
Next Stage
VE (Emergence)
Seedling emerges from soil
120 GDD needed
~11 days at current temps
In 1 day at current temps:
11 GDD
+11 GDD projected
Corn Growth Stage Chart
VE (Emergence)
Seedling emerges from soil
120
GDD
V3
Three visible leaf collars
200
GDD
V6
Six leaf collars — point of no return for row potential
475
GDD
V10
Ear size largely determined
750
GDD
VT (Tassel)
Pollen shed begins
1,135
GDD
R1 (Silk)
Silks emerge — critical pollination window
1,160
GDD
R3 (Milk)
Kernel filling begins
1,500
GDD
R6 (Black Layer)
Physiological maturity — grain filling complete
2,700
GDD
GDD calculation uses standard modified method: ((Tmax capped at 86°F + Tmin floored at 50°F) / 2) − 50. Stage thresholds from University of Illinois and Iowa State Extension.
Where to Find Your Accumulated GDD
Purdue Climate Hub
Indiana, Midwest
Daily GDD by county with crop-specific calculations
Iowa Environmental Mesonet
Iowa & Corn Belt
Station-by-station GDD data updated daily
Midwest Climate Watch
All 12 Midwest States
NOAA regional GDD maps and comparisons to average