Sprinkler Run Time Calculator
Once you know your zone's application rate (inches per hour), scheduling is simple division. This tool converts a weekly watering target into minutes per session for spray and rotary zones.
Inputs
Result
Planning estimate - not a substitute for a pressure-tested engineering design.
Formula
Minutes per day = weekly target (in) ÷ application rate (in/hr) × 60 ÷ watering days.
Example
1.5 in/hr sprays, 1 inch weekly target, 3 days: (1 ÷ 1.5) × 60 ≈ 40 min/week → about 13 minutes per day. A 0.5 in/hr rotary zone would need ~40 minutes per day for the same inch.
Assumptions
- Application rate is measured or calculated for the same zone (catch-cup tests are most accurate).
- No rainfall credit - subtract rain from the weekly target manually.
- Long single sessions may runoff; split them into cycle-and-soak.
Limitations
This tool is a planning aid for DIY design and pre-design work. It does not replace an on-site pressure and flow test, a catch-cup uniformity test, or local code and backflow requirements. For steep slopes, long pipe runs, large elevation changes or commercial-scale systems, have a qualified irrigation designer verify the plan before installation.
What This Means
The difference between spray and rotary run times surprises most people: the same inch takes 3-4× longer with rotaries because they apply water more slowly and more uniformly.
Next Step
Compute your rate from head data with the Sprinkler Calculator, or do the full plant-based version with the Irrigation Run Time Calculator.
Related Tools
Related Guides
Sources
Frequently Asked Questions
What is a catch-cup test and why use one?
Place identical cups across a zone, run it a fixed time, and average the depth collected - it measures your true application rate and uniformity, which nozzle charts only approximate.
Is 10 minutes enough for a lawn?
It depends entirely on the rate: 10 minutes at 2 in/hr applies 0.33 inch - fine as one of three sessions; the same 10 minutes on a 0.5 in/hr rotary applies only 0.08 inch.