Lawn Watering Schedule Calculator
Calculate how much water your lawn needs per week and create a watering schedule.
Based on lawn size, grass type, and your local climate zone.
Most lawns need 1 to 1.5 inches (25–38 mm) of water per week during the growing season. This includes both rainfall and irrigation. Watering the right amount — not too little and not too much — is the key to a healthy, resilient lawn.
How the calculation works:
Water Volume = Lawn Area × Water Depth per Week
Irrigation Needed = Target Depth − Estimated Rainfall
For example:
- A 2,000 ft² (186 m²) lawn needing 1 inch (25 mm) of water per week:
- 2,000 × (1/12) = 167 cubic feet = 1,250 gallons = 4,730 liters
Water requirements by grass type:
| Grass Type | Weekly Water Need | Climate |
|---|---|---|
| Bermuda grass | 1.0–1.25 in (25–32 mm) | Warm / hot |
| Zoysia grass | 0.75–1.0 in (19–25 mm) | Warm |
| St. Augustine | 1.0–1.5 in (25–38 mm) | Warm, humid |
| Kentucky bluegrass | 1.0–1.5 in (25–38 mm) | Cool |
| Tall fescue | 1.0–1.25 in (25–32 mm) | Cool, adaptable |
| Fine fescue | 0.75–1.0 in (19–25 mm) | Cool, shade |
| Ryegrass | 1.0–1.5 in (25–38 mm) | Cool |
When to water:
- Early morning (6–10 AM) is ideal — less evaporation, grass dries before nightfall.
- Evening watering leads to prolonged leaf wetness and promotes fungal disease.
- Avoid midday watering — most water evaporates before it reaches roots.
Signs of underwatering:
- Grass blades fold or roll lengthwise
- Footprints remain visible after walking across the lawn
- Bluish-gray tinge instead of green
Signs of overwatering:
- Constantly soggy or spongy soil
- Fungal patches, mushrooms, or moss
- Thatch buildup
- Runoff flowing off the lawn
Deep and infrequent watering builds deep roots: Water deeply 2–3 times per week rather than a little every day. Deep roots make your lawn drought-resistant and less susceptible to heat stress. Aim for water to penetrate 6–8 inches (15–20 cm) into the soil.
Sprinkler output check: Place empty tuna cans on the lawn while running your sprinkler. When cans hold 1 inch (25 mm) of water, you have watered the correct amount. Time how long this takes — that is your irrigation run time.