Quietest dishwasher: what dBA means, and Merit's dishwashers ranked from 38 dBA up

What does dBA mean when a dishwasher lists it?

Health Canada explains that scientists use A-weighted decibels, written dBA, to describe how loud a sound is to people. CCOHS adds that the A-weighting filter inside a sound meter turns down the low pitches. A dishwasher's rating is that measure, taken by the maker, for one machine running.

The decibel scale is logarithmic, which CCOHS describes as squeezing a huge span of numbers into a range people can work with. Its table of sound levels shows that a 3 dB rise doubles the sound energy. A 10 dB rise multiplies the energy by 10.

How loud that feels is a separate question. Hong Kong's Environmental Protection Department, in its noise education pages, says a sound is perceived twice as loud when its level rises by 10 dB. A 20 dB rise sounds about four times as loud to a normal ear.

The two health bodies round conversation a little differently, which is normal for a sound that changes with the voice and the room. Put into kitchen terms with the 10 dB rule, a 48 dBA dishwasher sounds about twice as loud as a 38 dBA one. The Whirlpool portable at 64 dBA is 26 dB above the quietest Bosch, so it should sound more than four times as loud.

Why dishwasher dBA ratings from different makers aren't always comparable

Dishwasher dBA ratings come from each maker's own testing, and the sheets don't say how. I read the spec sheets from Bosch, KitchenAid, LG, Samsung, Frigidaire, Electrolux and Midea for this guide. None of them names the test behind its number, the cycle it was measured on, or the distance from the machine.

An international test code exists. IEC 60704-2-3, revised in 2025, sets out how to measure the airborne noise of household dishwashers. It covers machines built in, fitted under a counter or standing against a wall. A maker's sheet sold here doesn't tell you whether its number follows it.

Comparisons inside one maker's sheets are a different matter. Bosch's sheet for the SHP95CM5N calls it the quietest dishwasher in its class, and the footnote defines the class. It's the top five brands by market share with advertised prices of $499-$1,249, by TraQline's count, on a sheet written for the American market. That's a price bracket, and it tells you nothing about a Samsung or a KitchenAid.

So I'd treat a gap of one or two dBA between two makers as a tie. A gap of six or more is worth paying attention to. And where our listing and the maker's sheet ever disagree, the maker's sheet wins.

What makes a dishwasher quiet: insulation, motor, tub and the third rack

A quiet dishwasher is mostly a well-wrapped one. LG's spec sheets for the SDWB24S3, LDNTH753S, LDNPH654S and LDNTH862S each list tub insulation: a damping sheet, sound-absorbing felt and a base. KitchenAid's installation manual for the KDPS324SPS tells the installer not to remove the insulation blanket, because the blanket reduces the sound level.

The motor is the other half. LG's sheets put its DirectDrive motor in the same list as its LoDecibel rating. LG backs that motor for 10 years on the SDWB24S3, the LDNTH753S, the LDNPH654S and the LDNTH862S. The Frigidaire and Electrolux sheets describe a multi-speed motor instead.

Some quiet machines add a cycle for late running. LG's manual for the LDNTH753S describes a Night Care cycle that washes quietly overnight. Many listings also show a delay start, which lets the load run once everyone is asleep. Knowing how long a modern cycle runs helps set that start time.

How plastic tubs show up in dishwasher dBA ratings

Tub material lines up with the ratings on Merit's listings, even though it isn't the only factor. Sixteen of our dishwashers list a plastic tub. Fifteen of them rate 51 dBA or louder, and the six loudest, from 57 to 64 dBA, are all plastic. The exception is the Frigidaire Gallery GDPH4525AF, a plastic tub at 42 dBA on Frigidaire's own sheet, and the least expensive dishwasher we list at that level.

The third rack follows the same pattern for a different reason. Among the 25 dishwashers rated 42 dBA or under, 24 list a third rack. None of the six at 57 dBA and up has one. A third rack doesn't quiet anything; it comes on the same higher trims that get the extra insulation. Loading a dishwasher with a third rack, and the two racks below it, follows rules of its own.

Installation that makes a quiet dishwasher louder

A quiet dishwasher can lose some of its rating in the installation. The makers' manuals name the usual causes, and each one is cheap to get right on the day it goes in.

1. Level it. LG's manual for the LDNTH753S warns that a dishwasher left out of level may leak, have trouble closing, or make noise. In a narrow opening, it says the machine should rest on all three levelling feet rather than hang from its brackets.
2. Keep the insulation blanket on. KitchenAid's manual says the blanket reduces the sound level. It allows trimming along a perforation only for a 33 5/8 inch opening.
3. Use the maker's lower cover. LG's manual says to fit only the lower cover supplied, and that a cabinet baseboard in its place may cause noise and leakage.
4. Fix any shims to the floor. Where new flooring stops short of the opening, KitchenAid's manual calls for shims, secured so they can't move while the dishwasher runs.
5. Expect a loud first drain. KitchenAid's manual says the drain pump sounds loud on the first run, since no water is in the system yet.

The room counts as much as the machine. In an open-plan kitchen there's no wall between the dishwasher and the sofa, so a few decibels make a bigger difference there. An island dishwasher faces the living area directly. Flush-fit models such as the KitchenAid KDTF924PPS and the LG FlushFit line are built to sit level with the cabinet fronts.

Built-ins take the same care as other built-in appliances. Our guide to built-in and freestanding wine coolers covers how an opening is measured. Appliance delivery and installation terms at Campbell River and Port Alberni are still being confirmed, so ask the store what its installers do when you order.

What a quiet dishwasher costs on Merit's listings

A quiet dishwasher costs more, but less than the top of the range suggests. In our two stores, the least expensive dishwasher at 42 dBA or under is $1,099.99, shared by the KitchenAid KDFS324SPS, the KitchenAid KDPS324SPS and the LG LDNTH753S. The least expensive at 38 dBA is the Samsung at $1,249.99. The Bosch Benchmark at $3,149 buys the same 38 dBA rating with a different set of features.

At the other end, the Amana ADFS2524RS lists from $499.99 at both stores and rates 59 dBA. The Samsung is 21 dB quieter for $750.00 more. By the 10 dB rule, that's a machine more than four times quieter to the ear.

Special orders widen the choice. The Frigidaire Gallery GDPH4525AF reaches 42 dBA at $749, and three special-order models reach 44 dBA at $999.99: the Whirlpool WDT550SAP, the Midea MDT24P6CST and the Samsung DW80B6060US.

A quiet dishwasher for open kitchens, condos, small spaces and night runs

A quiet dishwasher earns its price fastest where the kitchen shares space with sleep or work. That covers an open-plan main floor, a condo where the bedroom wall backs onto the kitchen, and a home office off the dining room. A busy household running a load after every meal hears its dishwasher more often, which makes the lower number worth more there too.

BC Hydro gives Islanders a reason to run it late. On its optional time-of-day pricing, electricity used overnight, from 11 p.m. to 7 a.m., gets a discount of 5 cents per kWh. Use from 4 to 9 p.m. carries the same 5 cent surcharge. BC Hydro's own tips suggest loading the dishwasher after dinner and setting a delay start for 11 p.m.

BC Hydro also warns that apartment or condo buildings may have noise restrictions that limit running a dishwasher late at night. If you live in a strata, check the bylaws before counting on an overnight cycle, and lean toward the low 40s or under.

Quietest dishwasher dBA for an 18 inch or portable machine

Small dishwashers on Merit's listings run louder than the 24 inch ones. The quietest 18 inch models are the Bosch 800 Series SPE68C75UC and SPV68C73UC at 44 dBA, both special orders at $1,899. In store, the Danby DDW18D1ESS rates 51 dBA and the Frigidaire FFBD1831US rates 52 dBA.

Portables are the loudest dishwashers we list. The Whirlpool WDP370PAH portable rates 64 dBA at $1,099.99, at both stores in black and at Port Alberni in white. The Danby countertop model at Port Alberni rates 52 dBA for $439.99. Both are among our portable and countertop dishwashers, and they suit renters who can't plumb in a built-in.