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Fluid Dynamics Utility

Pressure Washer & Nozzle Sizing Calculator

Ensure your machine operates in the safe 900 to 1,200 PSI detailing zone. Determine Cleaning Units (CU) and find the exact spray orifice tip size for your water flow.

Pressure Washer & Nozzle Sizing Calculator

Calculate Cleaning Units (CU), paint safety status, and optimal nozzle orifice sizes

1800 PSI
1.5 GPM
1000 PSI

Cleaning Units (CU)

2700

PSI × GPM

Recommended Tip Orifice

3.0

Use standard size: 3

Caution Zone (1800 PSI)

Maintain at least 18 inches of nozzle distance. Never focus stream on stone chips.

Understanding Nozzle Orifice Physics

An electric pressure washer pump tries to push a fixed volume of water. The smaller the nozzle hole (orifice), the higher the restriction and backpressure. If the hole is too large, pressure drops too low.

Standard pressure washer nozzles are rated by their orifice size at a nominal 4,000 PSI standard:

Orifice Size = Flow (GPM) × √(4000 / Working PSI)

Why You Should Never Use Stock 0° Red Tips

The red 0-degree nozzle concentrates the entire kinetic energy of your machine into a pinpoint stream with zero fan divergence. It can easily cut through rubber window seals, strip clear coat on rock chips, or damage automotive radar sensors. Always stick with 25° (green) or 40° (white) fan tips for car detailing.