Drone Ag Sprayer Swath GPA Calculator
Calculate gallons per acre for an agricultural spray drone from nozzle flow, flight speed and swath width, then size tank loads for the field.
How This Calculation Works
The GPA relationship is the same as for a ground rig: total nozzle flow in gpm times 5,940, divided by flight speed in mph times swath width in inches. Swath width is the effective spray width, often 20 to 40 feet for a spray drone. Acres per tank is tank capacity divided by GPA, which for a 10-gallon drone tank is usually a few acres.
Field Calibration & Rate Reference Chart
| Ground speed | Nozzle pressure | Typical GPA | Droplet class |
|---|---|---|---|
| 4 mph | 20 psi | 12 | Coarse |
| 5 mph | 25 psi | 14 | Coarse |
| 6 mph | 30 psi | 15 | Medium |
| 7 mph | 35 psi | 16 | Medium |
| 8 mph | 40 psi | 18 | Medium |
| 9 mph | 45 psi | 19 | Fine |
| 10 mph | 50 psi | 20 | Fine |
| 12 mph | 55 psi | 22 | Fine |
| 14 mph | 60 psi | 24 | Very fine |
| 16 mph | 65 psi | 26 | Very fine |
Common Questions
What swath width does a spray drone cover?
Most agricultural spray drones cover an effective swath of 20 to 40 feet depending on nozzle configuration, height and speed. The effective swath is narrower than the physical boom because edge coverage drops off. Confirm it with water-sensitive cards before calibrating.
How do I calculate GPA for a spray drone?
Sum the flow of all nozzles in gpm, multiply by 5,940, then divide by flight speed in mph times the effective swath in inches. The result is gallons per acre. Verify with a catch test on the ground.
How many acres can a 10-gallon drone spray?
At 2 GPA a 10-gallon tank covers 5 acres, and at 1 GPA it covers 10 acres. Lower volumes stretch coverage but reduce droplet density. Match the load to the battery so the drone does not run out of power mid-tank.
What flight speed should I use for drone spraying?
Most spray drones fly 8 to 12 mph, with slower speeds improving coverage and reducing drift. Faster speeds cover more ground but thin the deposit. Adjust speed to the product and wind conditions rather than holding one figure.