Center Pivot Calculator
Calculate center pivot irrigation coverage area, GPM requirements, and application depth per revolution.
Results
Visualization
How It Works
Center pivots rotate around a fixed point, irrigating a circular area. A standard quarter-section pivot (1,320 feet) covers about 128 acres. Application depth depends on speed — slower speed applies more water per pass. Most pivots need 5-6 GPM per acre.
The Formula
Circle Area = π × r² ÷ 43,560
Application/Rev = (GPM × 60 × Hours/Rev) ÷ (27,154 × Acres)
Actual Hours = Hours at 100% ÷ (Speed% ÷ 100)
Application/Rev = (GPM × 60 × Hours/Rev) ÷ (27,154 × Acres)
Actual Hours = Hours at 100% ÷ (Speed% ÷ 100)
Variables
- r — Total radius = pivot length + end gun/overhang throw
- Timer % — Speed setting — 100% is fastest, 50% takes twice as long per revolution
- 5-6 GPM/acre — Rule of thumb for adequate pivot water supply
Example
1,320 ft pivot + 60 ft end gun = 1,380 ft radius = 137 acres. At 800 GPM and 50% speed (40 hrs/rev): applies 0.64 inches per revolution.
Tips
- Minimum 5 GPM per irrigated acre for corn at peak ET demand.
- End guns add 15-20% coverage but waste water at the corners — consider corner systems.
- Faster speed with more frequent passes is better than slow heavy applications on tight soils.