1
An inch of water is a lot
Applying 1 inch of water over 1,000 square feet takes about 623 gallons, which is why small changes in depth can noticeably change runtime and water use.
Water use
Irrigation Depth / Run Time Calculator
Translate a target depth of irrigation water into actual runtime and applied volume.
Inputs & Parameters
Results
—
—
—
—
—
Interpretation—
Net target depth is divided by efficiency to find the gross depth the system must apply.
How Irrigation Depth / Run Time Works
This calculator starts with a target net irrigation depth, which is the amount of water you want available to the crop or landscape after losses. Because real irrigation systems are not perfectly efficient, the tool converts that net depth into a gross depth by dividing by system efficiency. That gross depth is then divided by the application rate to estimate how long the zone needs to run.
The page also converts the irrigation depth into total applied volume for the selected area. That is useful when checking pumping demand, comparing irrigation events, or estimating how much water a zone or block will use over time. Results are shown in both imperial and metric terms so the same estimate can fit field notes, audits, and equipment specs.
All calculations run locally in the browser. That makes the page useful for quick irrigation planning in farms, orchards, greenhouses, landscapes, and small properties without sending zone measurements or scheduling assumptions to a server.
Formula
Efficiency as a decimal = efficiency percent ÷ 100.
Gross depth = net depth ÷ efficiency.
Runtime = gross depth ÷ application rate.
Applied gallons = gross depth in inches × area in square feet × 0.623.
Example Calculation
A 1-inch target at 80% efficiency with a 0.5 in/hr application rate requires 2.5 hours of runtime and about 3,894 gallons on a 5,000 sq ft zone.
FAQs
What does the irrigation depth / run time calculator estimate?
It estimates how long a zone should run to apply a target net depth of water, then converts that irrigation depth into total gallons and liters for the selected area.
What is the difference between net depth and gross depth?
Net depth is the water you want stored in the root zone. Gross depth is the larger amount the system must apply after accounting for irrigation efficiency losses.
How do I find a realistic application rate?
Use measured precipitation or emitter output whenever possible. Catch-can tests, manufacturer data, and recent irrigation audits are better than rough guesses.
Can I use inches or millimeters and square feet or square meters?
Yes. The calculator accepts both imperial and metric units, then reports gross depth and water volume in both systems.
Should I still verify run time in the field?
Yes. Field pressure, nozzle wear, wind, runoff, and infiltration limits can all change actual performance, so measured output should still guide final scheduling.
Advertisement
5 Fun Facts
2
Efficiency changes everything
A system running at 70% efficiency must apply much more water than a system running at 90% efficiency to deliver the same net depth to the soil.
Losses
3
Application rate is usually measured
Sprinkler precipitation rates and drip output are best confirmed with catch-can tests, flow measurements, or recent audit data instead of assumptions.
Calibration
4
Run time is not the whole story
Soil intake rate, slope, and wind can matter just as much as the raw runtime estimate because they affect runoff, drift, and uniformity.
Field conditions
5
Cycling can improve infiltration
Long runtimes are often split into shorter sets with soak periods so water can move into the root zone instead of running off the surface.
Scheduling
Disclaimer
Use measured application rates whenever possible and consider runoff risk, infiltration limits, and rainfall.