Sprayer Nozzle Size Calculator: GPM per Nozzle and Flow at a New Pressure
Required GPM per nozzle from GPA, speed and spacing (5940 constant), flow at a new pressure by the square-root law, and a tip code decoder with the nearest standard size.
How this is calculated
Required GPM per nozzle. The formula is the published industry standard:
GPM = (GPA x MPH x nozzle spacing in inches) / 5940The 5940 constant collapses the unit chain: 1 acre = 43,560 sq ft, 1 mile = 5,280 ft, 1 hour = 60 min, and nozzle spacing is in inches (1/12 of a foot). The exact arithmetic: the denominator is 43,560 x 60 = 2,613,600; the numerator constant is 5,280 / 12 = 440; and 2,613,600 / 440 = 5,940 (Sprayer Guru, "Sprayer Calibration Formulas", retrieved 2026-10-24). In metric the equivalent is:
L/min = (L/ha x km/h x spacing in cm) / 60,000The 60,000 comes from the same dimensional analysis in metric units: 10,000 m2/ha, 1,000 m/km, 100 cm/m, 60 min/h. Area covered per minute = speed x 1,000/60 x width/100, in m2. Volume per minute = L/ha x area / 10,000. Combining: L/min = L/ha x km/h x cm / 60,000.
Square-root pressure law. Nozzle flow varies with the square root of pressure:
GPM₂ = GPM₁ x sqrt(P₂ / P₁)
P₂ = P₁ x (GPM₂ / GPM₁)²This follows from Bernoulli's equation for orifice flow. As Sprayer Guru puts it: "when you quadruple the operating pressure, the flow rate doubles." It means you cannot double your flow by doubling pressure: you need four times the pressure to double the flow, and going from 40 PSI to 60 PSI increases flow by only about 22%.
Tip capacity codes. The last two digits of a standard tip number are the rated GPM multiplied by 10 at 40 PSI, and the leading digits are the spray fan angle. For example, 8002 is an 80-degree tip rated at 0.2 GPM at 40 PSI; 11004 is a 110-degree tip rated at 0.4 GPM. TeeJet Catalog 52, p. 185, labels these on its Nozzle Nomenclature diagram as "0.4 GPM nozzle capacity rated at 40 PSI" and "110° Spray Angle" (retrieved 2026-10-25); the TPU8002-SS product page confirms "0.2 gpm @ 40 psi" for the 02 code (portal.spray.com/en-us/products/tpu8002-ss, retrieved 2026-10-25). The color code is universal across manufacturers, based on an ISO standard (Sprayer Guru, "Spray Nozzle Charts", retrieved 2026-10-24). A catch test with the sprayer calibration calculator confirms whether your tips are still within tolerance.
Everything runs in your browser. No account, no email gate, nothing stored or sent.
From a target rate to a nozzle, not the other way around
The sprayer calibration calculator on this site starts with what your sprayer is doing and checks it against what you want. This page starts with what you want and works forward to the nozzle that delivers it: enter the gallons per acre from the product label, the ground speed you will spray at and the nozzle spacing on your boom, and the formula gives you the required GPM per nozzle.
The formula is the same one published by Sprayer Guru (“Sprayer Calibration Formulas”, retrieved 2026-10-24):
GPM = (GPA x MPH x nozzle spacing in inches) / 5,940
The 5,940 constant is not arbitrary. It collapses the unit chain from acres, miles and inches into gallons and minutes: 43,560 sq ft per acre, 5,280 ft per mile, 60 minutes per hour, 12 inches per foot. The metric equivalent uses the same dimensional analysis and lands on 60,000: L/min = (L/ha x km/h x cm) / 60,000. Both constants are shown with their full derivation in the “How this is calculated” block, and a worked example from Sprayer Guru (10 GPA, 6 MPH, 30 in = 0.303 GPM) is pinned in the test suite.
Pressure changes flow, but not linearly
A tip rated at 0.2 GPM at 40 PSI does not deliver 0.4 GPM at 80 PSI. The relationship follows the square root of the pressure ratio: 0.2 x sqrt(80/40) = 0.283 GPM. As Sprayer Guru puts it, “when you quadruple the operating pressure, the flow rate doubles” (retrieved 2026-10-24). The inverse is just as useful: to find the pressure needed for a target flow, square the flow ratio and multiply by the known pressure. Both directions are on the page.
The tip code tells you the rated flow
Standard agricultural flat-fan tips carry a capacity code: 8002 is an 80-degree fan rated at 0.2 GPM at 40 PSI, 11004 is a 110-degree fan at 0.4 GPM, and so on. Enter the code and the page decodes it. Once you have a required GPM from section one, the page also suggests the nearest standard capacity code so you know which tip to look up on the manufacturer chart before you order.
The tip code and the square-root law work together: if the required GPM lands between two standard sizes, the pressure law tells you whether running the smaller tip at a higher pressure or the larger tip at a lower pressure stays inside the manufacturer’s recommended range. Check that against the nozzle chart before you commit, because spray quality (droplet size) shifts with pressure and the label may require a specific droplet category.
If your sprayer is already assembled and you want to know what it is actually putting down, the sprayer calibration calculator is the right tool. For backpack sprayers without a boom, the backpack sprayer calibration calculator covers the hand-wand method. And for total spray volume across a job, the spray coverage calculator works from the other end: area, rate and tank size.
Everything runs in your browser: no account, no email gate, nothing stored or sent. Calibration reference only, not a label substitute.
Frequently asked questions
Where does the 5940 constant come from?
How does the square-root pressure law work?
What do the digits in a tip number like 8002 mean?
How is this different from the sprayer calibration calculator?
Sources
- Sprayer Calibration Formulas: How to Calculate GPM & GPA. Sprayer Guru. Retrieved .
- Spray Nozzle Charts: Why They Are Important & How to Read Them. Sprayer Guru. Retrieved .
- TeeJet Catalog 52 (US): Technical Information, Nozzle Nomenclature, p. 185. TeeJet Technologies. Retrieved .
- TPU8002-SS Flat Fan UniJet Nozzle product page. Spraying Systems Co.. Retrieved .