Search for a quiet pressure washer and you will find plenty of marketing. What you will not find is data. We checked every major US brand and found exactly two that publish a noise figure at all.
We read the product pages and owner's manuals for fourteen models. Greenworks publishes 68 dB. Sun Joe publishes a sound power level, 96 dB(A) across almost its whole range and 89 dB(A) for one model. Everyone else publishes nothing.
Our 7 picks are listed above, with full specifications for each.
Two brands, two different measurements
This is the heart of it. The two published figures are not the same kind of number.
- Sun Joe prints "Sound power level is 89 dB(A)" or "96 dB(A)" in its manuals, as the explanation of a decal on the machine. Sound power describes total emission, and is always a higher number than the sound pressure most people picture.
- Greenworks says "Very quiet at only 68 dB" and lists "Low Noise 68 dB" in its specification block. It never says sound power or sound pressure, gives no distance, and names no standard. Its own manuals carry no acoustic declaration at all.
So a straight ranking would put Greenworks 28 decibels ahead of Sun Joe, and that would be meaningless. We have kept the two brands apart, and ranked within what each publishes. For the general problem, see why you cannot compare dB ratings across brands.
There is one comparison that does hold. Within Sun Joe's own range, using its own measurement, the SPX3000-MAX publishes 89 dB(A) while ten other models publish 96 dB(A). That 7 dB gap is like for like.
Nobody publishes anything for gas
We looked for gas models to use as loud reference points and could not source a single figure. Karcher's US gas range comparison table has no acoustic row. Neither do Champion, Simpson, Westinghouse or Generac.
A gas engine is obviously louder than an electric motor. But since no maker publishes the number, we will not invent one, and neither should the retailer listings that quote figures the manufacturer never published.
The induction motor myth
The standard advice online is that induction motors are quieter than universal ones. We went looking for a maker who says so.
None does. Sun Joe's manuals give only an amp rating, 13 amp or 14.9 amp, and never use either word. Greenworks says "Motor Type Brushless". No maker in this category ties motor type to a noise figure, so we cannot repeat the claim as fact.
What you can actually act on
Buy electric. Both published figures in this guide belong to electric machines, and no gas maker publishes anything.
Consider battery. Greenworks' battery models carry the lowest published figure, and you lose the cord.
Expect to wear hearing protection anyway. Sun Joe's manuals include a decal explaining the sound power level, which is there precisely because these are loud machines.
Ignore the retailer numbers. A "68 dBA at 23 ft" claim circulates for one gas machine and appears nowhere on that maker's own site.
Mistakes buyers make
Comparing 68 dB with 96 dB(A). Different quantities, from different brands.
Assuming the quietest badge means the quietest machine. Only two brands publish a figure at all, so most of the market is unranked.
Believing the induction motor claim. No maker publishes it.
Buying on peak PSI. Sun Joe distinguishes pressure at initial discharge from rated pressure under load; the second number is the useful one.
Expecting eco mode to be quieter. It lowers pressure, but no maker publishes a separate figure for it.
How we chose
We read each maker's US product page and owner's manual. We recorded every noise figure in the maker's own words, along with the quantity it describes where stated. We compared power source, pressure, flow, motor description, hose, nozzles, detergent capacity, weight and warranty, and recorded prices from the makers' own stores.
We did not measure anything ourselves, and we did not rank across the two measurement types. Greenworks' product URLs changed while we were working, so we re-read its pages and prices directly before publishing. Sun Joe lists several models whose manuals publish a figure but which it no longer sells, and those appear without a price.
New to the units? Read dBA explained. For other outdoor tools, see the quietest leaf blowers and the quietest air compressors.
