How this calculation works
Convert each collected water volume to litres per minute. Sum nozzle flow, use count times spacing as broadcast swath and divide by the area covered at the measured travel speed.
Water L/ha = 600 × total nozzle L/min / (speed km/hour × treated swath m)A worked example
Four catches of 500, 520, 480 and 500 mL over 30 seconds total 4 L/min. At 5 km/hour and 0.5 m nozzle spacing, the 2 m broadcast swath gives 240 L/ha.
Good to know
Water-only arithmetic, not pesticide-dose advice. Constant speed and equal broadcast spacing assumed. No band-spray model, pressure correction, wind or terrain simulation.
Reference: Penn State Extension: sprayer calibration information (opens in a new tab) ↗
Catch every nozzle for the same duration
Unequal collection times would turn volume differences into a misleading flow comparison. Record the same interval for each nozzle and enter millilitres rather than litres in the catch list.
The conversion divides by one thousand and scales seconds to minutes. Zero catches remain part of the comparison because excluding a stopped output would hide a real measurement difference.
The irrigation catch can uniformity calculator adds compare lower-quarter distribution uniformity, Christiansen coefficient and measured rate from equal-weight catches, keeping zero readings in the calculation.
Match the geometry to broadcast coverage
For equally spaced broadcast nozzles, the assumed swath is nozzle count multiplied by spacing. Total flow divided by area covered per minute then becomes litres per hectare.
This is not automatically suitable for band spraying or unusual overlap geometry. Use measured travel speed over the relevant conditions; a dashboard setting alone does not establish the speed used in the calculation.
Variation is descriptive rather than a pass mark
Each nozzle’s signed deviation shows whether its flow is above or below the group mean. The population coefficient of variation summarizes the entered set, using every nozzle rather than estimating a sample population.
The tool does not prescribe a replacement threshold, chemical concentration or application rate. A mathematically even set of catches does not prove adequate field distribution or compliance with a product label.
Use the result with the next measurement
The irrigation catch can uniformity calculator compares water delivered at locations. Nozzle flow consistency and spatial field delivery are different measurements; equal outlet flows do not by themselves establish an even field pattern.
Water-only arithmetic, not pesticide-dose advice. Constant speed and equal broadcast spacing assumed. No band-spray model, pressure correction, wind or terrain simulation.
A few questions, answered
Does this calculate pesticide dose?
No, only water-flow and coverage arithmetic.
Why keep zero catches?
Removing them would conceal the measured lack of output.
Is the CV a sample standard deviation?
No, it uses the whole entered nozzle population.