Garden Irrigation Calculator
Estimate how much water your vegetable garden needs each week, accounting for crop type, climate, rainfall, and irrigation method efficiency.
How It Works
Vegetable gardens generally need between 1 and 2 inches of water per week during the growing season. This calculator converts inches of water to gallons, subtracts rainfall, and adjusts for your irrigation method's efficiency so you know exactly how much water to apply.
The 0.623 Conversion Factor
One inch of water spread over one square foot equals 1/12 of a cubic foot. Since one cubic foot holds 7.48 gallons, 1 inch × 1 sq ft = 7.48 ÷ 12 = 0.623 gallons. This is the same formula used in rainwater harvesting calculations.
Watering Tips
Water deeply and infrequently: Apply 1–2 inches at a time, then let the soil dry slightly. This encourages deep root growth. Shallow, frequent watering produces shallow roots.
Water in the morning: Less evaporation and lower fungal disease risk. Avoid watering at night if possible.
Check soil moisture: Stick your finger 2 inches into the soil. If it's dry at that depth, it's time to water.