Sprayer calibration calculator (gallons per acre)
Before you mix a tank you need to know how much water the boom puts down. A sprayer calibration calculator works out gallons per acre from nozzle flow, ground speed and nozzle spacing, then how much area one tank covers and how much product goes in it.
Free to use. No sign-up, no email.
Results
- Spray volume
- 29.7 gal/acre
- Per 1,000 ft²
- 0.68 gal
- One tank covers
- 3.37 acres (146,667 ft²)
- Product per tank
- 6.73 units
Always follow the product label.
The formula behind the sprayer calibration calculator
Spray volume
GPA = GPM × 5,940 ÷ (MPH × W) (GPM per nozzle, W = nozzle spacing in inches)
5,940 is 60 minutes × 43,560 ft² per acre × 12 inches per foot ÷ 5,280 feet per mile.
Per 1,000 ft²
gallons per 1,000 ft² = GPA × 1,000 ÷ 43,560
One tank
acres per tank = tank gallons ÷ GPA · product per tank = label rate per acre × acres per tank
Metric
1 gal per acre = 9.354 L per ha · 1 mile = 1.609344 km · 1 inch = 2.54 cm
Derived from the exact gallon, foot and acre definitions below.
Where the numbers come from
- Sprayer output: GPA = GPM × 5,940 ÷ (MPH × W), W = nozzle spacing in inches; worked example 0.398 GPM, 5 MPH, 20 in → 23.64 GPA. Montana State University Extension, MontGuide MT 2000-14, “Calculations and Conversions for Pesticide Applications”
- Same formula, second source: W = nozzle spacing in inches. University of Arkansas Cooperative Extension FSA2212, “Calibrating Boom Sprayers”
- Pound, foot and acre: 1 lb = 453.59237 g, 1 ft = 0.3048 m, 1 acre = 43,560 ft² (all exact). NIST Handbook 44 (2024), Appendix C
- US gallon and fluid ounce: 1 gallon = 3.785411784 L (exact) = 128 fluid ounces. NIST Handbook 44 (2024), Appendix C
Worked example (the calculator opens with these numbers)
- Example inputs: 0.4 GPM per nozzle, 4 MPH, 20-inch nozzle spacing, 100-gallon tank, label rate 2 units per acre.
- Spray volume: 0.4 × 5,940 ÷ (4 × 20) = 29.7 gallons per acre.
- One tank covers: 100 ÷ 29.7 = 3.37 acres.
- Product per tank: 2 × 3.367 = 6.73 units.
Cross-check with the Montana State example: 0.398 GPM at 5 MPH with 20-inch spacing gives 23.64 gallons per acre here too.
Questions about the sprayer calibration calculator
What does GPA mean on a sprayer?
GPA is gallons per acre: how many gallons of spray mix the boom puts on one acre at a given nozzle flow, ground speed and nozzle spacing.
Where does the 5,940 in the sprayer formula come from?
The 5,940 in the sprayer formula converts the units: 60 minutes per hour times 43,560 square feet per acre times 12 inches per foot, divided by 5,280 feet per mile.
Does the sprayer calibration calculator replace calibrating the sprayer?
No. The sprayer calibration calculator does the arithmetic; nozzle flow and ground speed still have to be checked on your own sprayer, and the product label sets the rate.
Get this for your actual course
Cortex keeps every spray and fertilizer application on the map of your course, with the records your crew already keeps.
Questions? info@aetherisintel.com