How do I pick the right nozzle size?

Use the relation GPM = Nozzle × √(PSI/4000). Choose a nozzle number that delivers your target GPM at the desired working PSI without over-pressuring the pump.

What are Cleaning Units (CU)?

Cleaning Units are PSI × GPM. They provide a quick way to compare overall cleaning potential; however, task results depend on both impact (PSI) and rinsing (GPM).

How much pressure do I lose through the hose?

Loss depends on hose ID, length, fittings, and flow. The app uses Darcy–Weisbach with Swamee–Jain friction factor to estimate pressure loss and shows a chart vs hose length.

Pressure Washer Nozzle & Cleaning Units Calculator

Metric

Inputs

Target PSI

Working pressure desired at nozzle

Target GPM

Flow rate (pump/nozzle)

Nozzle Size #

Flow number (e.g., 2.0–15.0)

Solve For

Tip Angle (°)

Standoff Distance (in)

Overlap (%)

Walk Speed (ft/min)

Area to Clean (ft²)

Turbo Nozzle

Detergent

Water Temp

α: PSI weight in TCI

Hose ID (in)

Hose Length (ft)

Minor K (fittings)

Pump/Drive Efficiency (%)

Energy Cost

$ /kWh

Update URL as I type

Cleaning Units

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Task-Weighted Cleaning Index

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Working PSI at Nozzle

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Coverage Visualizer

Fan width, overlap & time-to-clean

Fan Width (in)

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Effective Pass Width (in)

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Time to Clean

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Water Use (gal)

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Efficacy Mix

Mechanical

Chemical

Risk & Suitability

Pressure Loss vs Hose Length

Nozzle Map (PSI vs GPM)

Job Summary

Saved Scenarios

#	PSI	GPM	Nozzle #	Angle	Distance	CU	TCI	Time

Formulas & Assumptions

CU = PSI × GPM
Nozzle: GPM = Nozzle × √(PSI/4000), PSI = 4000 × (GPM/Nozzle)²
Coverage: width w = 2 × d × tan(θ/2); pass width = w × (1 − overlap)
Time: T = Area / (pass_width × speed)
Hose loss: Darcy–Weisbach (Swamee–Jain)
HP ≈ (PSI × GPM)/(1714 × η), kW ≈ HP/1.341

Pressure Washer Nozzle & Cleaning Units (PSI × GPM & Orifice) Calculator