The short dBA meaning is A-weighted decibels: a sound level filtered so that it counts the pitches human ears hear best. Every guide on this site ranks products by a noise figure, and most of those figures carry dB or dBA. What follows covers what the letters stand for, what the number means, what it leaves out, and how often appliance makers print each unit.
We do not measure anything ourselves. Every statement here comes from a standards body, a government agency or a manufacturer, and we say which. The counts come from the maker figures in our own catalog.
What is a decibel?
The decibel, written dB, is the unit used to measure the intensity of a sound. The scale is not like a ruler. OSHA's technical manual explains that decibels are measured on a logarithmic scale, so a small change in the number of decibels indicates a huge change in the amount of sound pressure.
The scale exists because the ear hears an enormous range of pressures, and a logarithmic scale squeezes that range into manageable numbers.
Zero decibels is not silence. By definition, OSHA says, 0 dB is set at a reference sound pressure. That is worth remembering when a product is advertised at "0 dB", as some fanless heaters and absorption fridges are. It is a description, not a reading.
What does dBA stand for, and how is it different from dB?
dBA, sometimes written dB(A), stands for A-weighted decibels: a decibel reading that has been A-weighted to match how people hear.
People do not hear all pitches equally. The FAA puts it simply: we are less able to hear low frequencies like the rumble of thunder, but hear high frequencies like the cry of a baby more strongly.
A-weighting adjusts a measurement to match that. The FAA says the A-weighted scale most closely approximates the relative loudness of sounds in air as perceived by the human ear.
When a maker writes plain dB, you do not know whether the figure was weighted. In our guides we print the unit exactly as the maker wrote it, and we do not treat dB and dBA as the same thing.
How often do appliance makers print dBA instead of plain dB?
Appliance makers print dBA most of the time, but the habit depends on the product. We sorted the noise figures for 228 products in four catalogs by the unit the maker printed. The counts cover what our catalog held on October 26, 2026, not every model on sale.
| Catalog | Products | A-weighted figure (dBA, dB(A) or dBa) | Plain dB only | No figure published |
|---|---|---|---|---|
| Dishwashers | 111 | 109 | 2 | 0 |
| Refrigerators | 40 | 29 | 7 | 4 |
| Tower fans | 30 | 15 | 12 | 3 |
| Robot vacuums | 47 | 16 | 24 | 7 |
| All four | 228 | 169 | 45 | 14 |
A product counts as A-weighted if the maker labels its figure dBA, dB(A) or dBa anywhere in its own pages or documents. Plain dB only means every figure the maker gives lacks the A. We read each maker's wording ourselves before counting it.
Dishwashers: almost all dBA
Dishwasher makers have largely settled on dBA. Bosch prints "Silence Level 48 dBA" for its 100 Series SHE41CM5N, and GE, Samsung, Frigidaire, Thermador and Whirlpool print the same unit. The two exceptions are an LG Studio model listed at "39dB" and a Gaggenau listed at "42 dB (re 1 pW)".
That Gaggenau label, re 1 pW, marks sound power, a different quantity. Sixteen of the 111 dishwashers carry it: 15 Miele models and the Gaggenau. Those Miele and Gaggenau figures belong beside each other, never beside a Bosch dBA, and the page on sound power vs sound pressure gives the reasons.
Robot vacuums and tower fans: mostly plain dB
Robot vacuum makers mostly skip the A. Tapo, eufy, Roborock and most Narwal and Dreame pages print plain dB, often inside a product image. Ecovacs is the exception, with a spec table row that reads "noise-standard mode -sweep (dBA) 61.8" for the Deebot X11.
Among tower fans, every Dreo figure we found is plain dB, including the support page line "about 35dB at the lowest speed". Lasko and Vornado label theirs, and Lasko writes it as "dBa".
When one maker prints both
The A comes and goes even within one maker's pages. On 43 of the 169 products with an A-weighted figure, the same maker also prints a figure without the A on another line, page or document.
LG lists its LDPH5554S at "LoDecibel Quiet Operation: 46 dBA" in the spec table and "LoDecibel Operation (46 dB)" in the feature text. Liebherr's US spec sheet for the SC5781 says "Sound rating dB(A)" 33, while the product page says "Noise level 33 dB". Miele's G 7766 SCVi data sheet reads dB(A) re 1 pW, and its product page headline reads "39 dB".
So a missing A does not always mean an unweighted figure, and a present A does not make two figures comparable. The unit is one clue among several.
How much louder is 3 dB, and how much is 10 dB?
A rise of 3 dB means twice the sound power, and a rise of 10 dB sounds about twice as loud. Those are the two numbers worth remembering.
Is 3 dB double?
OSHA states it as a general rule: doubling the sound power increases the noise level by 3 dB. By that rule, two identical fans running side by side are about 3 dB louder than one.
Is 10 dB twice as loud?
The National Park Service explains that an increase of 10 dB causes a doubling of perceived loudness, and represents a ten-fold increase in sound level.
In its words, if one vacuum cleaner measures 70 dB, then 80 dB would be the equivalent of ten vacuum cleaners. Each further 10 dB doubles the perceived loudness again, so 20 dB is about four times as loud.
The calculator below applies both rules to any two figures, and also moves a figure to a new distance using the 6 dB rule covered further down.
Worked example: two Bosch dishwashers
Bosch lists the Benchmark SHP9PCM5N at 38 dBA and the 100 Series SHE41CM5N at 48 dBA. The gap is 10 dB: ten times the sound energy, and about twice as loud to the ear. Because both figures come from one maker on the same "Silence Level" line, the comparison is as fair as published figures get.
A smaller gap reads differently. Bosch lists the 800 Series SHX78DM5N at 42 dBA and the 300 Series SHP53EM5N at 46 dBA. That 4 dB gap is about 2.5 times the sound energy, but only around 1.3 times as loud.
Across brands, the same arithmetic can mislead. Samsung lists its Bespoke DW90F89T0USRAA at 38 dBA and Miele its G 7766 SCVi at 39 dB(A) re 1 pW. The 1 dB gap means nothing, because the Miele number is sound power and the Samsung number is not labelled as either.
That matters most where brands sit close together, as the built-in models in our dishwasher guide do. Our Bosch dishwasher figures list every Silence Level in one maker's range.
How does distance affect decibels?
Sound fades as you move away from its source, and makers rarely state how far away they measured. OSHA gives the rule for open space: the sound pressure level decreases 6 dB each time the distance from a point source is doubled.
Two things follow. First, a figure with no distance attached is incomplete. None of the 228 products in the table above states a measuring distance. Portable generators are the exception among appliances, and even there the distances differ: one maker measures from 23 feet and another from 22.
Second, a room is not open space. OSHA notes that where sound reflects off surfaces, the level decreases by less than 6 dB each time the distance doubles. So the figure a maker measured, in whatever space it used, is not the figure you will hear in a furnished room.
Why is the noise rating on the box so low?
The single figure on a box is usually the quietest one available. We have now read the noise claims for more than 3,000 products, and that pattern is consistent.
Lowest speed.
Tower fan, portable air conditioner and heater makers often quote an "as low as" figure. Dreo footnotes one of its figures as tested at the lowest speed setting. Our tower fan guide notes the speed behind each figure.
Quiet mode.
Robot vacuum figures usually describe quiet mode. Dreame's blog gives four modes for one robot, from 59 dB in Quiet Mode to 70 dB at Max. Our robot vacuum guide says which mode each figure describes, where the maker tells us.
Light load.
Honda lists its EU2200i generator at 48 dB(A) at quarter load and 57 at rated load.
The gentle half of the cycle.
For a compact washer, Bosch lists 52 dBA during the wash and 72 dBA during the spin. A single "quiet" figure for a washer probably describes the wash.
No cycle at all.
Dishwashers show the opposite problem. Only 4 of the 111 in our catalog tie the figure to a named cycle: three Fisher & Paykel DishDrawers rated "on standard cycle top drawer", and JennAir, whose range page footnotes "Based on Normal Cycle." The other 107 give a number and nothing else.
None of these figures is false. Each describes a real moment in the product's life. The question to ask is whether it is the moment you care about.
The makers that publish both ends deserve credit, and our guides rank them above makers that publish one flattering number. You can see this at work in the guides to portable air conditioners, generators and washing machines.
How loud are 30, 40 and 60 decibels in everyday life?
For everyday reference points in the US, the federal hearing institute known as the NIDCD rates a whisper at 30 dB and a refrigerator's hum at 40 dB, while ordinary talk between two people runs 60 to 70 dBA.
The National Park Service notes that some remote park trails measure around 20 dBA, softer than a whisper.
Use these as a rough scale only. A maker's 40 dB and a refrigerator's 40 dB were not measured the same way or from the same distance.
Refrigerators show the problem well: see our refrigerator guide for what each maker's number measures. Our decibel chart sets more everyday levels beside the figures makers publish, band by band.
How do you read a decibel rating?
Ask five questions of any noise figure, in this order, before you let it decide a purchase.
- Find the setting the figure describes, and assume the quietest one if the maker does not say.
- Look for a second figure at the loud end, since a maker that publishes both ends tells you more.
- Read the unit: dBA and plain dB differ, re 1 pW or B(A) marks sound power, and sones are a separate scale.
- Check for a measuring distance, and without one compare only with figures from the same maker.
- Size the gap, treating 10 dB as twice as loud and 2 or 3 dB between brands as no proven difference.
Bathroom fans and range hoods carry sones rather than decibels, and sones vs decibels covers how to read those.
