Today
—
in/week
—
Crop Water Use Calculator
ETc = Kc × ET₀
×
=
ETc (in/week)
—
ET₀ is pre-filled with today’s typical value for the selected county.
Enter your crop’s Kc — or click a value from the table below.
Crop Coefficient Reference
Kc changes through the season, use the stage that best matches your crop’s current development. Click any value to load it into the calculator.
| Crop | Initial | Development | Mid-season (peak demand) |
Late season |
|---|---|---|---|---|
| Winter Wheat | 0.30 | 0.70 | 1.15 | 0.40 |
| Corn | 0.30 | 0.75 | 1.20 | 0.60 |
| Soybean | 0.40 | 0.80 | 1.15 | 0.50 |
| Grain Sorghum | 0.30 | 0.70 | 1.05 | 0.55 |
| Sunflower | 0.35 | 0.75 | 1.10 | 0.35 |
| Alfalfa | 0.40 | 0.95 | 1.20 | 1.15 |
Source: FAO Irrigation & Drainage Paper No. 56 (Allen et al., 1998). Values are approximations.