Calculator · Outdoor power equipment
Pressure washer nozzle selector
Choose the tip colour for the surface, then check which nozzle size number fits your washer's flow and pressure.
Calculator
Tip for a deck, fence or siding: 25° green. Pick the published size closest to the calculated number, and check its pressure rating.
Nozzle colors and what each one is for
| Tip | Color | Use it for |
|---|---|---|
| 0° | Red | Narrowest, hardest jet. Small stubborn spots on concrete or metal only; it can cut wood and skin. |
| 15° | Yellow | Hard surfaces: concrete, stains, paint prep. |
| 25° | Green | Everyday cleaning: decks, fences, siding, outdoor furniture. |
| 40° | White | Gentle rinse: cars, windows, boats. |
| Soap (wide, low pressure) | Black | Applies detergent at low pressure. |
The colors mark spray angle only. Brands use the same five colors, but check your manual before you use a tip from another kit.
How the size number works
Size = GPM × √(4,000 ÷ PSI). It is a size number from the nozzle maker's chart, not a hole diameter in inches.
Worked examples
| Flow | Pressure | Size number |
|---|---|---|
| 4 GPM | 4,000 PSI | 4.0 |
| 2.5 GPM | 3,000 PSI | 2.9 |
Questions people ask
Which nozzle should I start with?
Start with the widest tip that does the job, usually the white 40° or green 25°, and move narrower only if the dirt will not come off.
Is the colour the same as the size?
No. The colour shows the spray angle. The size number sets the orifice and must match your washer's flow and pressure.
Sources
Change log: Nov 6, 2026: Rebuilt to spec: sourced reference data, formulas and worked examples; no unverified people or test claims.