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Sprayer Calibration Calculator
Calculate gallons per acre (GPA) using the standard calibration formula. Essential for every pesticide applicator.
GPA Calculator
Formula: GPA = (Nozzle Output x 5,940) / (Speed x Nozzle Spacing)
Collect output from one nozzle for 1 minute in a measuring cup
Measure by timing travel over a known distance at operating conditions
Distance between nozzles on the boom (commonly 20 or 30 inches)
Common Presets
Understanding the Formula
Why 5,940?
The constant 5,940 converts between measurement units: 1 acre = 43,560 sq ft, 1 mile = 5,280 ft, 1 hour = 60 minutes, 1 gallon = 128 oz, and 1 foot = 12 inches. These combine to: (1 x 5,280 x 60) / (128 x 12 x 43,560 / 43,560) = 5,940.
Key Relationships
- Doubling speed cuts GPA in half
- Doubling nozzle output doubles GPA
- Doubling nozzle spacing cuts GPA in half
- Doubling pressure increases output by only ~41% (square root relationship)
Calibration Tips
- Collect nozzle output for a full 60 seconds for accuracy
- Replace any nozzle that varies more than 10% from the average
- Measure ground speed at actual field operating conditions
- Recalibrate whenever you change nozzles, pressure, or speed
- Verify by spraying a measured area and checking volume used