Liquid Fertilizer GPA to Weight Calculator
Convert a liquid fertilizer gallons-per-acre rate into pounds of product and pounds of nutrient per acre using the solution density and analysis.
How This Calculation Works
Pounds of product per acre equals gallons per acre times the solution density in pounds per gallon. Pounds of nutrient per acre is that product weight times the analysis percentage divided by 100. For a 28-0-0 UAN solution at 10.67 pounds per gallon, 10 GPA delivers about 107 pounds of product and 30 pounds of nitrogen per acre.
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
How do I convert gallons per acre of liquid fertilizer to pounds per acre?
Multiply gallons per acre by the solution density in pounds per gallon. A 10.67 pound-per-gallon UAN at 10 GPA gives about 107 pounds of product per acre. Then multiply by the analysis percentage to get pounds of nutrient.
What is the density of 28-0-0 UAN?
28-0-0 UAN weighs about 10.67 pounds per gallon at 60 degrees Fahrenheit. Density changes slightly with temperature, so cool solutions are denser. Use the supplier's figure for accurate rate math.
Why does my sprayer apply less fertilizer than water?
A denser fertilizer solution flows differently through the nozzle and can reduce output compared with water. Recalibrate with the actual product or apply a density correction to the water-calibrated GPA. Viscosity and temperature also affect flow.
How do I calculate pounds of nitrogen per acre from GPA?
Multiply GPA by the solution density to get pounds of product per acre, then multiply by the nitrogen analysis percentage divided by 100. For 28-0-0 at 10 GPA, that is 107 pounds of product times 0.28, or about 30 pounds of nitrogen per acre.