Drip Irrigation Calculator — Flow & Timer Comparison
Compare water delivered to different plant groups on one timer. Use rated emitter flow or a measured catch test, and see which groups receive more or less than their entered target.
DRIP IRRIGATION · ONE TIMER, MANY PLANTS
One timer. See what every plant gets.
Enter your water target and emitter output. Compare plant groups on the same timer, or measure the real flow with a catch test.
Example: 24 plants with one 0.5 GPH emitter each receive 0.5 US gal per plant in 60 minutes: 12 US gal for the whole zone.
Catch water from representative emitters for the same time. Enter their combined collected volume. The result uses their average, not a guarantee for every emitter.
Compare your timer setting
Every group reaches its entered target at 60 minutes.
Garden plants
0.5 US gal per plant · target 0.5 US gal · 100% of target
60 min to target · 0.5 US gal/h per emitter · 24 plants × 1 emitter
The target is yours to choose from soil moisture, plant needs and local guidance. “100%” means your entered volume, not a recommended watering dose. If groups need different times, compare separate zones or emitter arrangements; running longer also increases water for groups already at their target.
How the flow and timer comparison works
Flow per plant = emitters per plant × flow per emitter. Target minutes = target water per plant ÷ flow per plant × 60. Total zone flow adds all plant groups. Water delivered = flow × timer minutes ÷ 60. The number of plants changes total water and zone flow, but not that group’s target time.
A catch test uses combined mL ÷ 1,000 ÷ sampled emitters ÷ test minutes × 60 to find litres per hour per emitter. Use representative samples from near and far parts of the zone under normal operating conditions. An average does not show which individual emitter is clogged or whether distribution is uniform.
1 US gallon = 3.785411784 litres. Unit changes preserve the same physical water amounts. The comparison uses unrounded values; displayed numbers are rounded. The bar shows 0–200% of your target, with larger deliveries reported in text.
This tool compares one session, up to six groups, and a timer up to 24 hours. It does not choose crop water demand, assess pressure loss, design pipes, or prove available supply capacity. Confirm actual output, filtration and pressure regulation against your equipment. If water pools, follow local guidance for shorter cycle-and-soak runs.
Measurement method: UC Agriculture and Natural Resources: emitter evaluations. For your next step: plant spacing · rainwater collection.
