FIELD TOOL GUIDE · Irrigation design
Center-pivot irrigation calculator
Calculate irrigated area, gross/net depth, pass time and required flow for a center pivot.
Method: Circular sector · water accounting
Open this calculator →Inputs and units
Use measurements representative of your field, crop or irrigation system. The values below are illustrative examples.
| Input | Unit | Example value |
|---|---|---|
| Irrigated radius (end gun excluded) | m | 400.000 |
| Irrigated sector angle | degrees | 360.000 |
| Measured total system flow | L/s | 50.000 |
| Time for one pass over this sector | h | 24.000 |
| Application efficiency | % | 85.000 |
| Target net irrigation depth | mm | 10.000 |
Worked example
These are calculated demonstration values from the existing tool, not measured field results or a site-specific recommendation.
| Calculated quantity | Example result | Unit |
|---|---|---|
| Irrigated sector area | 50.265 | ha |
| Delivered water per pass | 4,320.000 | m³ |
| Gross mean depth per pass | 8.594 | mm |
| Estimated net depth per pass | 7.305 | mm |
| Time for the target net depth | 32.853 | h |
| Flow for target at entered pass time | 68.444 | L/s |
| Whole-area equivalent application rate | 0.358 | mm/h |
| Angular travel rate | 15.000 | degrees/h |
| Net depth minus target | -2.695 | mm |
Water accounting for one pass over the selected circular sector. Confirm measured flow, application efficiency and the actual irrigated boundary in the field.
Whole-area equivalent mm/h is flow divided by the complete sector area. It is not the instantaneous application rate under the outer sprinklers and must not be used alone for an infiltration or runoff check.
The duration refers to one pass over the entered angle. End guns, corner arms, overlaps, obstacles, variable-rate sectors and downtime are excluded. No timer setting or pump/valve control is calculated.
Check the nozzle package, pressure losses, wetted width, soil intake, slope and manufacturer limits separately. A center-pivot uniformity test needs radial area weighting; the drip-emitter CU tool does not provide that test.
Assumptions and limitations
- The radius is the actual irrigated circular radius; end guns and corner systems are excluded. The selected sector is watered once with constant total flow.
- Efficiency is an explicit user estimate of useful root-zone storage, not a quantity inferred from pivot type, uniformity or weather. Net target should account for rainfall and soil water separately.
- This preliminary accounting does not design the lateral, nozzle package, pressure regulation, pump, local peak application rate or mechanical travel settings.
Use your measurements in this calculator →
Public method guides and labelled examples are freely readable. Phase 1 calculations, weather data and exports are free without registration. Register with a verified email only to save private work or upload a personal station dataset.
Related guides
Sources
Conservation of water for a circular/sector pass, expressed in SI. Field-average depth and local sprinkler intensity are different quantities.