| Metric | Value | Copy |
|---|---|---|
| System | {{ system_type }} | |
| Precipitation rate | {{ precip_rate_value }} {{ precip_rate_unit }} | |
| Zone flow | {{ zone_flow_gph.toFixed(2) }} GPH | |
| Days per week | {{ days_per_week }} | |
| Net depth / event (in) | {{ net_depth_event_in.toFixed(3) }} | |
| Gross depth / event (in) | {{ gross_depth_event_in.toFixed(3) }} | |
| Gallons / event (gross) | {{ event_gallons.toFixed(2) }} | |
| Runtime / event (min) | {{ runtime_per_event_minutes.toFixed(2) }} | |
| Runtime / week (min) | {{ (runtime_per_event_minutes*days_per_week).toFixed(2) }} | |
| Cycle/soak | {{ cycles }} × {{ cycle_minutes.toFixed(1) }} min, soak {{ soak_minutes }} min | |
| Gallons / event (gross) | {{ event_gallons.toFixed(2) }} | |
| Gallons / week (gross) | {{ (event_gallons*days_per_week).toFixed(1) }} |
Irrigation runtime is the watering time a zone needs so plants receive the depth of water that matches their demand. It helps translate plant water use and system output into minutes you can schedule with confidence.
You choose between spray heads and drip emitters, then supply recent weather driven demand and a simple plant factor, or set a target depth. The calculator returns minutes per event and an estimate of gallons where area is known, so you can plan days per week and check whether you need short cycles that reduce runoff.
A common case is a lawn zone with a moderate demand week. Enter the application rate, the plant factor, and days per week. The result shows the runtime per event and, if you know the area, gallons per event and per week. If the soil can take water slowly, you may see a split into shorter cycles with soak time between runs.
Inputs work best when units are consistent and recent. Use realistic plant factors and application rates, and review results when weather shifts. Valid patterns guide watering time, yet they do not confirm local rules or restrictions.
The calculator models plant water use for a period and converts it to runtime using your system output. Plant demand is represented by reference evapotranspiration scaled by a crop coefficient. For drip systems, total zone flow is derived from emitter flow and count; for sprinklers, output is represented as an application rate across the area.
Weekly plant water use is computed first, then divided across the selected number of irrigation days to obtain the net depth per event. System losses are handled by an application efficiency factor and a distribution uniformity factor, producing the gross depth or volume that must be applied to meet the net requirement.
Results include minutes per event, minutes per week, and estimated gallons where area is supplied. When the soil intake rate is below the sprinkler application rate, runtime is split into equal cycles with a user set soak period between cycles to reduce runoff.
| Symbol | Meaning | Unit/Datatype | Source |
|---|---|---|---|
| ETo | Reference evapotranspiration (daily or weekly) | in/day or in/week | Input |
| Kc | Crop coefficient (plant factor) | unitless | Input |
| ETcweek | Weekly plant water use | in | Derived |
| PR | Sprinkler application rate | in/hr | Input |
| Eff | Application efficiency | 0.01–1 | Input |
| DU | Distribution uniformity factor | 0.5–2 | Input |
| Dnet,event | Net depth per event | in | Derived/Input |
| Dgross,event | Gross depth per event | in | Derived |
| A | Watered area | sq ft | Input |
| Vevent | Gallons per event (gross) | gal | Derived |
| Qzone | Total drip flow | GPH | Derived |
| tevent | Runtime per event | min | Derived |
Runtime is 14.0 min per event with about 87.2 gal per event. Infiltration at 0.5 in/hr does not require cycle/soak here.
| Field | Type | Min | Max | Step/Pattern | Error Text | Placeholder |
|---|---|---|---|---|---|---|
| Precipitation rate | number | 0 | — | 0.01 | — | — |
| ETo | number | 0 | — | 0.01 | — | — |
| Kc (sprinkler) | number | 0 | 1 | 0.01 | — | — |
| Kc (drip) | number | 0 | 1.5 | 0.01 | — | — |
| Target depth per event | number | 0 | — | 0.01 | — | — |
| Days per week | integer | 1 | 7 | 1 | — | — |
| Area | number | 0 | — | 0.1 | — | — |
| Application efficiency | integer % | 1 | 100 | 1 | — | — |
| DU factor | number | 0.5 | 2 | 0.01 | — | — |
| Infiltration rate | number | 0 | — | 0.01 | — | — |
| Soak between cycles | integer | 0 | — | 1 | — | — |
| Emitter flow | number | 0 | — | 0.01 | — | — |
| Emitters (total) | integer | 1 | — | 1 | — | — |
| Weekly gallons (net) | number | 0 | — | 0.1 | — | — |
| Input | Accepted Families | Output | Encoding/Precision | Rounding |
|---|---|---|---|---|
| Numbers, units | in/hr, mm/hr, GPH, LPH, sq ft, m² | Minutes, gallons, depths | Floating point | Fixed decimals as noted |
| Days per week | 1–7 | Per‑event and weekly metrics | Floating point / integer | Fixed decimals as noted |
All calculations run locally. No data is transmitted or stored server‑side. Downloads are generated on your device.
Set plant demand and system output to obtain runtime per event and weekly totals.
Example: Sprinkler, ETo 1.5 in/week, Kc 0.7, three days per week, 1.5 in/hr rate, 400 sq ft area → 14.0 min per event and 87.2 gal per event.
No. All calculations run on your device and downloads are created locally.
No server storage.Accuracy depends on realistic inputs. Application rate, plant factor, and area dominate outcomes; rounding is limited to display.
Garbage in, garbage out.Sprinklers use in/hr or mm/hr; drip uses GPH or LPH; area can be sq ft or m²; demand is inches per day or week.
Unit conversions are built in.If application rate only slightly exceeds soil intake, one or two cycles may suffice. Increase soak time if puddling appears.
Observe and adjust.Use a reasonable range: turf about 0.7 to 0.9, shrubs about 0.4 to 0.7, vegetables about 0.8 to 1.1.
Choose values that match growth stage.Yes for drip. Enter weekly gallons and days per week to compute minutes per event from zone flow.
Efficiency and DU still apply.Area is optional for sprinklers. It does not change minutes, but enables gallon estimates.
Depth drives minutes; area drives volume.