Choose the orifice size
The nozzle must pass the pump's flow at the intended pressure. General Pump and Cat Pumps publish the standard pressure-washer relationship in which a nozzle number is its approximate GPM capacity at 4000 PSI.
Home Pressure Washer Nozzles: Sizes, Types & Compatibility
Nozzle sizing & selection
Pressure Washer Nozzles: Sizes, Types & Compatibility
Choose a pressure washer nozzle by separating two decisions: the orifice size that matches GPM and pressure, and the spray pattern that matches the cleaning task.
The two numbers people often mix up
Spray angle describes the fan pattern. Nozzle size describes the orifice capacity. A 25° green tip can still be the wrong nozzle if its orifice is not sized for the machine's GPM and working pressure.
Technical references reviewed: August 28, 2026.
Pressure washer nozzle selection has two separate jobs
Choose the spray pattern
After the orifice class is correct, select the spray angle for the surface and task. A wider fan spreads impact; a narrow stream concentrates it. Surface condition and safe standoff distance still matter.
What a nozzle number such as 3.0, 4.0 or 5.5 means
The nozzle number is not the opening diameter in millimetres and it is not the spray angle. In the standard pressure-washer convention, the number corresponds to the nozzle's approximate flow in GPM at 4000 PSI. General Pump's current chart, for example, shows a #4.0 nozzle at 4.00 GPM at 4000 PSI and about 3.46 GPM at 3000 PSI.
0°, 15°, 25°, 40° and soap nozzles
| Common color | Pattern | Typical role | Compatibility note |
|---|---|---|---|
| Red | 0° | Very concentrated high-impact stream | High surface-damage risk; use only where appropriate and maintain safe distance. |
| Yellow | 15° | Heavy cleaning / stripping | Still verify the orifice size and pressure rating. |
| Green | 25° | General cleaning | Common general-purpose fan, but color does not establish nozzle size. |
| White | 40° | Wider, gentler coverage | Useful where a wider fan is appropriate; test delicate surfaces first. |
| Black | Soap / low pressure | Detergent application on compatible systems | Designed to create the low-pressure condition required by many downstream detergent systems. |
SIMPSON's current 80145 and 80146 five-tip kits use this red/yellow/green/white/black convention and 1/4-inch quick-connect plugs. Other nozzle systems may use different markings, so the exact product specification controls.
Nozzle size and spray angle are independent
A nozzle can be marked 25040: the first digits identify a 25-degree fan while the ending digits commonly identify a #4.0 orifice class. Manufacturers vary in how they print or encode tip markings, so verify the product data instead of relying on a partial stamp you cannot confidently decode.
This separation is why replacing a green 25° tip with another green tip is not enough. If the original is a #3.0 and the replacement is a #4.0, the fan angle may look right while the operating pressure changes materially.
Why a smaller orifice is not automatically better
The nozzle is the restriction that allows a positive-displacement pressure-washer pump to develop pressure. Too large an orifice can reduce pressure because it passes more flow at the same pressure. Too small an orifice can push the system toward a higher pressure than intended or make the unloader bypass excessively.
Do not use nozzle sizing as a pressure upgrade. The pump, engine/motor, unloader, hose, gun, wand, fittings and accessory limits remain the ceiling. If the calculated orifice would be used to exceed a published rating, stop and size the system to the manufacturer's limit instead.
Turbo and rotating nozzles need sizing too
A turbo nozzle does not eliminate the orifice-sizing requirement. General Pump sells rotating nozzles in specific nozzle sizes—current examples include #2.5, #3.5, #4.0 and other classes—with published pressure, temperature and inlet specifications. Its ROTOMAX literature describes the rotating action as expanding the contact area while retaining the impact of a zero-degree stream.
Match the rotating nozzle's size/flow class, maximum pressure, temperature and inlet connection. A listing that says only “up to 5000 PSI” is not enough to establish that it is the correct rotating nozzle for a 2.5, 4 or 8 GPM machine.
Nozzle wear changes system pressure
The nozzle orifice is a wear point. As the opening enlarges, the same pump flow produces less pressure. If a machine that previously reached its normal working pressure gradually loses pressure while flow and the rest of the system remain healthy, nozzle wear is one item to inspect before changing pump or unloader settings.
Replace a worn nozzle with the correct documented size; do not compensate by deliberately installing an undersized tip.
After the nozzle size and connection are known
For a standard wand with a 1/4-inch quick-connect socket, compare nozzle sets only after confirming the required orifice class, pressure/temperature rating and spray patterns. Turbo nozzles require the same sizing discipline.
Technical sources
- General Pump — Nozzle Chart (2025) — nozzle-number, orifice-diameter and GPM/PSI reference.
- General Pump — catalog nozzle formulas — published nozzle-number, GPM and PSI relationships.
- Cat Pumps — Standard Nozzle Selection Chart — confirms nozzle number as GPM capacity at 4000 PSI and the same sizing formulas.
- SIMPSON — Replacement Spray Nozzles 80146 — current color/angle roles, 1/4-inch QC and #4.0 example.
- General Pump — ZREX14040 rotating nozzle — current rotating-nozzle example with #4.0 nozzle size and published operating limits.
- Cat Pumps — Pressure Washer Troubleshooting — worn-nozzle guidance explaining that an enlarged orifice reduces resistance and system pressure.
Frequently asked questions
What size pressure washer nozzle do I need?
Match nozzle size to the machine flow and the target operating pressure. Nozzle size is an orifice-capacity number, not the spray angle. Use the nozzle calculator or a manufacturer nozzle chart rather than choosing only by color.
What do the pressure washer nozzle colors mean?
On common quick-connect nozzle sets, red is 0 degrees, yellow 15 degrees, green 25 degrees, white 40 degrees and black is soap/low pressure. The color describes spray pattern or function; it does not tell you the correct orifice size for your machine.
Are pressure washer nozzles universal?
No. Many spray tips use a common 1/4-inch quick-connect plug, but connection type, nozzle/orifice size, pressure rating, temperature rating and intended function still have to match the system.
Is a smaller pressure washer nozzle more powerful?
A smaller orifice creates more restriction and can raise pressure, but that does not make it a safe upgrade. An undersized nozzle can force the unloader to bypass and can increase stress on the pump and other components.
How is a turbo nozzle different from a standard spray tip?
A turbo or rotating nozzle rotates a concentrated high-impact stream over a wider contact area. It still has a nozzle-size/flow class and pressure, temperature and connection limits that must be matched to the pressure washer.