How do you calibrate a boom sprayer?

Catch flow from one nozzle at operating pressure to get GPM, then divide by ground speed times spacing and multiply by 5940. At 0.25 GPM, 5 mph, and 20-inch spacing (product 120), you get 12.375 GPA.

What is the 5940 number in sprayer calibration?

It is the unit-conversion constant that makes gallons per acre come out right when nozzle flow is in GPM, speed in MPH, and spacing in inches. It bundles the conversions between minutes, miles, and square feet per acre.

What is a good gallons-per-acre for spraying?

It depends on the target: 10-15 GPA is common for broadcast herbicides, while fungicides and contact products often want 15-20+ GPA for coverage. The 12.375 GPA result suits many systemic herbicide programs.

How do I enter ground speed and spacing?

Multiply your ground speed in MPH by nozzle spacing in inches and enter that single product. For 5 mph and 20-inch tips, enter 120.

Why is my calculated GPA different from my actual coverage?

A worn or plugged nozzle, wrong pressure, or inaccurate GPS speed will make the boom's real output differ from a single-nozzle calculation. Catch-test several nozzles and verify speed to close the gap.

Nozzle GPM vs gallons per acre, what is the difference?

GPM is the instantaneous flow from one tip; GPA is that flow spread over the ground you cover at your speed and spacing. This calculator converts the first into the second using the 5940 constant.

Agriculture, Soil, Fertilizer & Farm Operations calculator

Sprayer Calibration Calculator

Sprayer calibration converts a single nozzle's measured flow, your ground speed, and nozzle spacing into the gallons of carrier applied per acre. Every applicator needs this number because the entire pesticide rate rides on it, if the boom is putting out 12 GPA when you assumed 15, every product is under-dosed by 20 percent. The 5940 constant is the standard English-unit factor that ties GPM, MPH, and inch spacing together. Running this before a spray season, or after any nozzle or pressure change, is basic due diligence.

What this calculator does

Calculate sprayer gallons per acre from nozzle flow, ground speed, nozzle spacing, and the standard 5940 calibration factor.
Use it to check boom sprayer calibration before applying crop protection products or foliar nutrients.
It computes the gallons of spray solution applied per acre from measured nozzle output, ground speed, and nozzle spacing.

Formula used

Spray volume = nozzle GPM / (ground speed MPH x nozzle spacing inches) x 5940

Inputs explained

Nozzle output at operating pressure: Use measured nozzle flow from a catch test at the intended pressure.
Ground speed times nozzle spacing: Multiply sprayer ground speed by nozzle spacing in inches before entering.
Boom sprayer 5940 constant: Use 5940 for gallons per acre with GPM, MPH, and inches.

How to use the result

Use it before each season, whenever you swap nozzles or change pressure, and any time actual coverage looks off versus tank empties.
It assumes uniform nozzle output across the boom; a single plugged or worn tip means the boom average differs from this single-nozzle calculation.

Current U.S. benchmarks

U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, Jun 2026). New factory orders are up 2.3% year over year (Census).
Industrial natural gas averages $4.9 per Mcf (EIA, Apr 2026), down 7.7% from a year earlier, with industrial electricity at 8.66 cents per kWh. Process heating and refrigeration budgets track both.

Common questions

How do you calibrate a boom sprayer? Catch flow from one nozzle at operating pressure to get GPM, then divide by ground speed times spacing and multiply by 5940. At 0.25 GPM, 5 mph, and 20-inch spacing (product 120), you get 12.375 GPA.
What is the 5940 number in sprayer calibration? It is the unit-conversion constant that makes gallons per acre come out right when nozzle flow is in GPM, speed in MPH, and spacing in inches. It bundles the conversions between minutes, miles, and square feet per acre.
What is a good gallons-per-acre for spraying? It depends on the target: 10-15 GPA is common for broadcast herbicides, while fungicides and contact products often want 15-20+ GPA for coverage. The 12.375 GPA result suits many systemic herbicide programs.
How do I enter ground speed and spacing? Multiply your ground speed in MPH by nozzle spacing in inches and enter that single product. For 5 mph and 20-inch tips, enter 120.
Why is my calculated GPA different from my actual coverage? A worn or plugged nozzle, wrong pressure, or inaccurate GPS speed will make the boom's real output differ from a single-nozzle calculation. Catch-test several nozzles and verify speed to close the gap.

Last reviewed 2026-05-12.