Irrigation Pivot Sizing Calculator

Pivot length from field radius and water source.

Field length (ft)

Peak ET (in/day)

System run time (hrs/day)

Application efficiency (%)

Outer tower speed (ft/min)

Number of spans

Tab to move between fields

Irrigated area (acres)

125.7

Required flow (GPM)1,004

Rotation time (hours)23

Span length (ft)189

Total coverage w/ end gun131.9

% of quarter section82.5

App Per Rev0.35

How to Use This Calculator

Enter Field Length (ft) — the shorter dimension; pivot radius is half this (a quarter section = 2,640 ft).
Set Peak ET (in/day) for your crop at peak demand (corn peak: 0.25–0.35 in/day).
Enter System Run Time (hrs/day), Application Efficiency (%), and Number of Spans.
Set Outer Tower Speed (ft/min) — slower speeds apply more water per pass.
Review Irrigated Acres, Required Flow (GPM), Rotation Time (hours), and Coverage % of Quarter Section.

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