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Irrigation Requirement Calculator
Convert a watering depth into run times per zone from your system's application rate, and account for soil infiltration and runoff.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Unit & Converters
Irrigation Requirement Calculator
Frontend preview — no upload or external service.
Run time
25 mm at 12 mm/hour needs 2 hours 5 minutes a week. On clay, split into three cycles of about 42 minutes to avoid runoff.
How the Irrigation Requirement Calculator works
- Measure your application rate with catch cans rather than trusting the manufacturer's figure.
- Divide the target depth by the rate to get total run time.
- Split the run into cycles on clay or on a slope, since water applied faster than the soil absorbs it runs off and is wasted.
The method
Run time is simply depth divided by application rate, but soil infiltration rate caps how fast that depth can actually soak in.
run time = target depth ÷ application rate; split into cycles if rate > infiltration rate
Clay might absorb only 5 mm per hour, so a 12 mm/hour sprinkler puts down more than the soil can take and the excess runs off.
FAQ
How do I measure application rate?
Put straight-sided containers around the zone, run it for fifteen minutes, and measure the depth collected. Multiply by four for the hourly rate. It is usually different from the specification, and it reveals uneven coverage too.
Why split the run into cycles?
Because soil absorbs water at a limited rate. Applying faster than that produces runoff, so several shorter cycles with soak time between them deliver the same depth with none wasted.
Is deep and infrequent better than daily?
For established plants, generally yes — it encourages deeper roots. Seedlings and shallow-rooted crops are the exception and need lighter, more frequent watering.
How we compare
| Feature | Online Tool Store | A search-engine answer box | A reference table |
|---|---|---|---|
| Cycle splitting for clay | ✓ | ✗ | Sometimes |
| Uses measured application rate | ✓ | Spec sheet | ✓ |
| No controller software | ✓ | ✓ | ✗ |
| Nothing stored | ✓ | ✓ | ✗ |
Irrigation Requirement Calculator caps run time by infiltration rate, since water applied faster than the soil takes it simply runs off the bed.