3000 PSI target
A #3.5 row shows about 3.03 GPM at 3000 PSI, making it much closer than a #3.0 or #4.0 for this theoretical combination.
Home Pressure Washer Nozzle Chart
GPM / PSI reference
Pressure Washer Nozzle Chart
Use this reference table to match pressure-washer nozzle size, GPM and PSI. Keep nozzle orifice sizing separate from spray-angle color selection.
How to use this reference
Rows are nozzle-size numbers. Columns are working pressure. Cells are approximate GPM per nozzle. For multiple identical nozzles, compare the chart to flow per nozzle—not total machine flow.
Values follow the General Pump / Cat Pumps nozzle relationship and align with General Pump's current nozzle chart.
Pressure washer nozzle size chart
This table focuses on the pressure range most useful for pressure-washer selection. General Pump's manufacturer chart extends beyond this subset and should be used when you need other pressure points or exact published orifice-diameter data.
| Nozzle # | 1,000 PSI | 1,500 PSI | 2,000 PSI | 2,500 PSI | 3,000 PSI | 3,500 PSI | 4,000 PSI | 5,000 PSI |
|---|---|---|---|---|---|---|---|---|
| 2 | 1.00 | 1.22 | 1.41 | 1.58 | 1.73 | 1.87 | 2.00 | 2.24 |
| 2.5 | 1.25 | 1.53 | 1.77 | 1.98 | 2.17 | 2.34 | 2.50 | 2.80 |
| 3 | 1.50 | 1.84 | 2.12 | 2.37 | 2.60 | 2.81 | 3.00 | 3.35 |
| 3.25 | 1.62 | 1.99 | 2.30 | 2.57 | 2.81 | 3.04 | 3.25 | 3.63 |
| 3.5 | 1.75 | 2.14 | 2.47 | 2.77 | 3.03 | 3.27 | 3.50 | 3.91 |
| 3.75 | 1.88 | 2.30 | 2.65 | 2.96 | 3.25 | 3.51 | 3.75 | 4.19 |
| 4 | 2.00 | 2.45 | 2.83 | 3.16 | 3.46 | 3.74 | 4.00 | 4.47 |
| 4.5 | 2.25 | 2.76 | 3.18 | 3.56 | 3.90 | 4.21 | 4.50 | 5.03 |
| 5 | 2.50 | 3.06 | 3.54 | 3.95 | 4.33 | 4.68 | 5.00 | 5.59 |
| 5.5 | 2.75 | 3.37 | 3.89 | 4.35 | 4.76 | 5.14 | 5.50 | 6.15 |
| 6 | 3.00 | 3.67 | 4.24 | 4.74 | 5.20 | 5.61 | 6.00 | 6.71 |
| 6.5 | 3.25 | 3.98 | 4.60 | 5.14 | 5.63 | 6.08 | 6.50 | 7.27 |
| 7 | 3.50 | 4.29 | 4.95 | 5.53 | 6.06 | 6.55 | 7.00 | 7.83 |
| 7.5 | 3.75 | 4.59 | 5.30 | 5.93 | 6.50 | 7.02 | 7.50 | 8.39 |
| 8 | 4.00 | 4.90 | 5.66 | 6.32 | 6.93 | 7.48 | 8.00 | 8.94 |
| 8.5 | 4.25 | 5.21 | 6.01 | 6.72 | 7.36 | 7.95 | 8.50 | 9.50 |
| 9 | 4.50 | 5.51 | 6.36 | 7.12 | 7.79 | 8.42 | 9.00 | 10.06 |
| 9.5 | 4.75 | 5.82 | 6.72 | 7.51 | 8.23 | 8.89 | 9.50 | 10.62 |
| 10 | 5.00 | 6.12 | 7.07 | 7.91 | 8.66 | 9.35 | 10.00 | 11.18 |
| 12 | 6.00 | 7.35 | 8.49 | 9.49 | 10.39 | 11.22 | 12.00 | 13.42 |
| 15 | 7.50 | 9.19 | 10.61 | 11.86 | 12.99 | 14.03 | 15.00 | 16.77 |
| 20 | 10.00 | 12.25 | 14.14 | 15.81 | 17.32 | 18.71 | 20.00 | 22.36 |
Cell values = approximate GPM through one nozzle at the stated pressure. Example: a #4.0 nozzle passes about 4.00 GPM at 4000 PSI and 3.46 GPM at 3000 PSI.
Reverse lookup examples
3000 PSI target
The exact theoretical nozzle is about #4.62, which falls between common #4.5 and #5.0 sizes. Use the calculator to compare resulting pressure.
4 GPM machine
Use 2 GPM per nozzle before reading the chart. Do not select each nozzle as if it receives the full 4 GPM.
Pressure washer nozzle color chart
| Common color | Spray pattern | Common use | What color does not tell you |
|---|---|---|---|
| Red | 0° | Concentrated stream / very aggressive cleaning | Orifice size, pressure rating or connection |
| Yellow | 15° | Heavy-duty cleaning / stripping | Orifice size, pressure rating or connection |
| Green | 25° | General cleaning | Orifice size, pressure rating or connection |
| White | 40° | Wider, gentler fan | Orifice size, pressure rating or connection |
| Black | Soap / low pressure | Detergent draw on compatible systems | Whether your chemical-injection system will operate correctly |
SIMPSON's current replacement nozzle kits use this common color convention. Treat it as a spray-pattern reference, not a sizing chart.
Nozzle size vs. physical orifice diameter
The nozzle-size number is a flow-capacity designation, not a direct diameter measurement. General Pump's current chart also publishes physical orifice diameters: for example, #2 is listed at 0.032 inch, #2.5 at 0.036 inch and #3 at 0.040 inch. Use the manufacturer's table when a physical orifice diameter is required.
Formula behind the table
GPM per nozzle = Nozzle # × √(PSI ÷ 4000)
Equivalent forms: Nozzle # = GPM × √(4000 ÷ PSI) and PSI = (GPM ÷ Nozzle #)2 × 4000.
If your exact operating point falls between chart cells, use the Pressure Washer Nozzle Calculator rather than guessing from the nearest cell.
Chart limitation
The table predicts the nozzle-flow relationship; it does not account for hose/fitting pressure loss, pump wear, water-supply limitations, unloader behavior or engine/motor limitations. Do not select a smaller nozzle to push the system beyond any published rating.
Technical sources
- General Pump — Nozzle Chart (2025) — current nozzle size, physical orifice and GPM/PSI table.
- General Pump — catalog reference formulas — formula set used to generate the table values.
- Cat Pumps — Standard Nozzle Selection Chart — independent manufacturer confirmation of the same convention and relationships.
- SIMPSON — Replacement Spray Nozzles 80146 — current red/yellow/green/white/black angle/function reference.
Frequently asked questions
How do I read a pressure washer nozzle chart?
Find your nozzle-size row and move across to the pressure column to read the approximate GPM that one nozzle passes at that pressure. Or find the GPM/PSI combination nearest your machine and identify the corresponding nozzle size.
Does nozzle color tell me the nozzle size?
No. Red, yellow, green and white commonly identify spray angles, while the nozzle size number identifies orifice capacity. A green 25-degree nozzle can be sold in many different orifice sizes.
Why does nozzle size equal GPM at 4000 PSI?
That is the standard pressure-washer nozzle-number convention documented by General Pump and Cat Pumps. A #4 nozzle is approximately a 4 GPM nozzle at 4000 PSI; at other pressures the flow changes according to the square-root relationship.
How do I use the chart for a two-nozzle surface cleaner?
Divide the machine flow by the number of identical nozzles first. Then use the per-nozzle flow and target pressure to select each nozzle. Also confirm the surface cleaner manufacturer's own flow, pressure and nozzle requirements.
Can I use the chart to increase my pressure washer PSI?
Do not use a smaller nozzle to exceed the machine or component ratings. The chart describes the theoretical flow/pressure relationship; it does not authorize a pressure upgrade.