Free tool

Pesticide calibration calculator

Work the boom, speed, tank, and active-ingredient formulas before you leave the yard. Nothing here is saved and nothing is locked.

Boom sprayer — GPA and GPM

Target GPATravel speed (mph)Nozzle spacing (inches)

GPM = (GPA × MPH × W) / 5,940
= (15 × 5 × 20) / 5,940
= 0.253 GPM per nozzle

If you already caught this GPM

GPA = (GPM × 5,940) / (MPH × W) = (0.25 × 5,940) / (5 × 20) = 14.85 GPA

Use 495 instead of 5,940 only when spacing is in feet. 5,940 ÷ 12 = 495.

Travel speed from a test course

Course length (feet)Time (seconds)

MPH = (feet × 60) / (seconds × 88)
= (176 × 60) / (15 × 88)
= 8.00 mph

88 feet per minute equals 1 mph because 5,280 ÷ 60 = 88. An 88-foot course in 10 seconds is 6 mph.

Active ingredient — dry and liquid

Dry product, percent a.i. (75WP = 75)Pounds of dry product per acreTarget pounds of a.i. per acreLiquid, lb a.i. per gallon (4EC = 4)Gallons of liquid product per acre

Dry a.i. = 2 × (75 / 100) = 1.500 lb a.i./acre
Dry product for the target = 1.5 / (75 / 100) = 2.000 lb product/acre
Liquid a.i. = 0.25 gal × 4 lb/gal = 1.000 lb a.i./acre
Liquid product for the target = 1.5 / 4 = 0.375 gal/acre (48 fl oz)

1 gallon = 128 fl oz = 4 quarts = 8 pints. One pint of 4EC is 0.125 gal × 4 = 0.5 lb a.i.

Tank load

Tank gallonsGPAProduct gallons per acre

Acres per tank = 300 / 15 = 20.00 acres
Product per full tank = 0.25 × 20.00 = 5.000 gallons

Nozzle uniformity

Catch, 4 to 8 nozzles, fluid ounces

Catch time (seconds)

Mean catch 19.00 fl oz · mean 0.148 GPM

Nozzle	fl oz	GPM	From mean	Action
1	16	0.125	-15.8%	Replace
2	18	0.141	-5.3%	Keep
3	20	0.156	5.3%	Keep
4	22	0.172	15.8%	Replace

Replace only when the absolute difference from the mean is greater than 10 percent. A nozzle at exactly 10 percent stays. GPM = (fl oz × 60) / (128 × seconds).