In band applicator calibration, what is the formula used to calculate GPA?

• A. (Distance traveled x Band width) / Gallons used
• B. (Gallons used x Distance traveled) / (43,560 x Band width)
• C. (43,560 x Gallons used) / (Distance traveled x Band width x number of bands)
• D. (Gallons used) / (Distance traveled x Band width)

Answer: (C)

GPA means gallons per acre, the rate at which the sprayer delivers product over an acre. In band application you’re spraying multiple narrow bands across the field, so you need to relate the total gallons used to the actual area covered. The area sprayed is the distance traveled times the width of each band times the number of bands, all in square feet. Since there are 43,560 square feet in an acre, acres sprayed = (distance × band width × number of bands) / 43560. Gallons per acre is gallons used divided by acres sprayed, which simplifies to GPA = (43560 × gallons used) / (distance × band width × number of bands). This is why the correct form includes 43,560 and the number of bands.

If there’s only one band, that number of bands is 1, and the formula becomes GPA = (43560 × gallons used) / (distance × band width). The other expressions miss either the 43,560 conversion or the number of bands, so they don’t yield the correct GPA. For a quick check, plug in a sample: 600 ft traveled, band width 2 ft, 3 bands, 5 gallons used. Area sprayed = 600×2×3 = 3600 ft²; acres sprayed ≈ 0.0825. GPA ≈ 5 ÷ 0.0825 ≈ 60.6 gal/acre, which matches the formula (43560×5)/(600×2×3).