Irrigation Scheduling
Weekly irrigation needed after rain and system efficiency.
About Irrigation Scheduling
Rain is subtracted from the crop's evapotranspiration, then the deficit is scaled up for system losses. Scheduling against actual evapotranspiration instead of a fixed timer saves water and avoids root stress.
Formula
Irrigation Scheduling
Apply = (crop use - rain) / efficiency; gallons = inches/12 x area x 7.48
- 7.48
- Gallons per cubic foot of water
- efficiency
- Share of emitted water that reaches the crop
Worked example
With the default values below, Irrigation Scheduling returns Water to Apply of 1.41. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Crop water useminimum 0 in
- 1.5 in
- Rain receivedminimum 0 in
- 0.3 in
- System efficiencyaccepts 10–100 %
- 85 %
- Watered areaminimum 1 sq ft
- 1,000 sq ft
Results
- Water to Apply
- 1.41 in
- Gallons per Week
- 880 gal
- Gallons per Day
- 126 gal
Step by step
- 1Values used
- 2Irrigation Scheduling
- 3Water to Apply= 1.41 in
- 4Gallons per Week= 880 gal
- 5Gallons per Day= 126 gal
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Irrigation Scheduling calculated?
Apply = (crop use - rain) / efficiency; gallons = inches/12 x area x 7.48 Rain is subtracted from the crop's evapotranspiration, then the deficit is scaled up for system losses.
Why does Irrigation Scheduling matter?
Scheduling against actual evapotranspiration instead of a fixed timer saves water and avoids root stress.
What values do I need to enter?
This calculator takes 4 inputs: Crop water use, Rain received, System efficiency, Watered area. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.