Free Online Drip/Sprinkler Irrigation Application Rate Calculator

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Drip & Sprinkler Irrigation — Application Rate and Uniformity

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Inputs

Average emitter flow rate, q		X
Minimum emitter flow rate, q_min		X
Emitter spacing along lateral, S_e		X
Lateral spacing (row spacing), S_l		X
Emitters per lateral, n_e		X
Laterals per zone, n_l		X
Target application depth, d		X

Results

Area per emitter, A_e	Area per emitter, A_e	X
Application rate (precipitation rate), PR	Application rate (precipitation rate), PR	X
Distribution uniformity, DU	Distribution uniformity, DU	X
DU quality check	DU quality check	X
Flow per lateral, Q_lat	Flow per lateral, Q_lat	X
Zone flow, Q_zone	Zone flow, Q_zone	X
Runtime for target depth (hours)	Runtime for target depth (hours)	X

Application Rate: PR = q / A_e, where A_e = S_e × S_l is the area served by each emitter. A lower application rate gives more time for infiltration — important on heavy soils or sloped fields.
Distribution Uniformity (DU): DU = q_min / q_avg. A DU of 1.0 (100%) means all emitters flow identically. Values below 0.80 waste water on well-watered areas while leaving drier spots. Uniformity drops with excessive pressure variation along the lateral, emitter wear, or partial clogging.
Runtime: Runtime = target depth ÷ application rate. On sloping or compacted soil, split the runtime into two or three shorter cycles with rest periods between them to avoid surface runoff.