What Size Orifice Does a Foam Cannon Need?
Most foam cannons ship with a 1.25mm orifice, and that suits many mid-range pressure washers. Pick a smaller orifice, such as 1.1mm, for lower-pressure machines and a larger one, such as 1.35mm, for higher-pressure machines. Check your washer's PSI first, then match it to the range printed for the orifice.
Tool Daily JT001-1Lightest in the lineup
Tool Daily JT067Gun included, M22 fittings
MJJC QRFLPROV3Biggest soap bottleThe short version: match the orifice to your pressure
The orifice is a small jet inside the cannon. Water from your pressure washer is forced through it, and that is what pulls soap up from the bottle and mixes it into foam. If the hole is too large for your machine, the pressure drops and the foam comes out thin and wet. If it is too small, the machine works harder and the flow can feel restricted.
So the right size depends mainly on your washer's pressure rating, measured in PSI. Flow rate, listed in GPM, matters too, but PSI is the number most cannon makers use when they describe which orifice to choose.
Many foam cannons come with one orifice already installed. Some include extras so you can swap to fit a different machine. Our best foam cannon page flags which models list swappable orifices, which is worth checking before you buy.
Common orifice sizes and the pressure they suit
The clearest published numbers in our data come from the MJJC Pro V3.0. Its listing gives specific pressure ranges for each orifice, shown below. Other makers often list the sizes but not the pressure range for each one, so treat this table as one maker's guidance rather than a universal rule.
| Orifice size | Listed pressure range (MJJC Pro V3.0) | Notes |
|---|---|---|
| 0.9mm | 725 to 1305 PSI | Optional, sold separately |
| 1.1mm | 1305 to 1595 PSI | Included |
| 1.25mm | 1595 to 2175 PSI | Included, pre-installed |
| 1.35mm | 2175 to 4061 PSI | Included |
| 1.65mm | 4061 to 4931 PSI | Optional, sold separately |
How to find your washer's PSI
Look at the rating plate or the product manual for your pressure washer. The PSI figure is usually printed near the GPM figure. If your machine lists pressure in bar instead, the MJJC listing pairs 90 to 280 bar with 1305 to 4061 PSI, which gives a rough sense of the conversion across that range.
If you cannot find a rating, check the maker's website using your model number. Avoid guessing, because an oversized or undersized jet changes how the foam behaves.
What the foam cannons in our data list
Several cannons on our comparison page state their swappable orifices or pressure ranges. Here is what the published listings say.
The details vary a lot, and some makers leave out the pressure range altogether. That is why it helps to confirm your washer's rating against the cannon's listing before you order.
- MJJC Pro V3.0: three orifices (1.1mm, 1.25mm and 1.35mm) covering 1305 to 4061 PSI.
- The Rag Company Ultra H2O: interchangeable 1.1mm and 1.25mm orifices.
- Tool Daily JT001-1 and JT067: swappable orifice listed, with a 1000 to 3000 PSI working range. The listing does not give the orifice size.
- McKillans Wide Mouth: no swappable orifice or pressure range listed in our data.
How to swap an orifice safely
Swapping the jet takes a few minutes, but treat the cannon like pressurized equipment. Always do this with the washer off and the trigger gun released so no pressure is trapped in the line.
Follow these steps. Check your cannon's manual first, because the layout differs between models.
- Turn off the pressure washer, then squeeze the trigger to release any stored pressure.
- Disconnect the cannon from the wand or gun and empty the bottle.
- Unscrew the fitting that holds the orifice, usually at the front of the body.
- Remove the old jet and drop the new one in, keeping the parts clean and in the same orientation.
- Reassemble snugly, reconnect, and test the spray pointing at the ground, away from people and pets.
Tuning the foam after you pick a size
Once the right orifice is in, the foam knob and spray pattern control the final result. The knob sets how much soap mixes with water, and the pattern setting changes the fan shape. Not every cannon lists both, so check the spec table on our best foam cannon page if you want that control.
Soap matters as well. Foam thickness depends heavily on the shampoo you use, so a good orifice match will not fix a weak soap. Warm water in the bottle can also help the soap mix.
Wear eye protection when you work with a pressure washer, since spray and soap can bounce back. Keep the spray away from your skin, and keep the washer's electric cord and outlets dry. Use a GFCI-protected outlet for electric machines.
Connector fit comes first
An orifice only helps if the cannon actually connects to your washer. Most models in our data use a 1/4 in quick connect, and several listings say they will not fit a garden hose or faucet. Confirm your wand or gun fitting before you worry about jet size.
The Tool Daily JT067 is the one in our data that includes a gun with M22 fittings, listed for both 14mm and 15mm hoses. Check which fitting your hose uses so everything lines up.
Frequently asked questions
Can I use a foam cannon with a garden hose?
Not the pressure washer type. Several listings in our data say they will not fit a garden hose or faucet. Garden hose users need a different type of foam gun.
Does a bigger orifice make thicker foam?
Not by itself. A larger jet suits higher pressure, and using it on a weaker machine usually gives thinner foam. Soap quality, the foam knob and water mix also affect thickness.
What if my cannon only comes with one orifice?
Check the listed pressure range for your cannon. If your washer falls inside it, the stock jet should work. If your washer is outside it, look for a model with swappable orifices.
How do I know if my orifice is clogged?
Weak or sputtering foam, or a spray that looks uneven, can point to debris. Shut the washer off, release the pressure and rinse the jet. Never poke it with a sharp tool that could scratch the opening.