To compare decibel levels between two products, both figures need the same setting, distance, quantity and test standard. Most maker figures state none of those, which is why almost every guide on this site warns against lining up one brand's number with another's. This page shows where the comparison breaks down, with real examples and counts from our catalog, and the few comparisons that do hold up.
We do not measure anything ourselves. Every example here comes from a manufacturer's own page or manual, or from a government source, and we name it.
Why does one blower have four noise figures?
A leaf blower can carry four noise figures because each answers a different question: how loud the blower is for the person holding it, for a neighbor, or in total. Start with the clearest example we found. Husqvarna's manual for its 125B leaf blower lists four noise figures for the same machine:
- 93 dB(A), the sound pressure at the operator's ear, measured to ISO 22868
- 71 dB(A), the sound pressure at a bystander's ear, measured to ANSI B175.2
- 106 dB(A), the sound power level, as measured
- 110 dB(A), the sound power level Husqvarna guarantees
None of these is wrong. But if one maker prints the 71 and another prints the 93, the second blower looks far louder even if it is identical.
That is the core problem. A decibel figure means nothing on its own. It needs to say what was measured, where, and how.
What should a noise figure tell you?
A comparable noise figure answers four questions: which setting, how far away, sound pressure or sound power, and which standard. Most published figures answer one or none.
1. Which setting?
Most appliances have more than one speed, and the quietest speed can be twenty or more decibels below the loudest.
Blueair lists its Blue Pure 411i Max at 19 dB on low and 46 dB on high. That is a 27 dB spread in one product.
Winix lists its L201 humidifier at 30 dB at its highest speed.
Many makers give a single number and do not say which setting it describes.
So Winix's 30 dB, which describes the loudest setting, may be quieter in use than another maker's 24 dB that describes the quietest. Without the setting, you cannot tell. Our guides to quiet air purifiers and bedroom humidifiers note the setting behind each figure wherever the maker gives one.
2. How far away?
Sound gets quieter as you move away from it, so a figure measured close to a machine reads higher than one taken farther away. OSHA notes that indoors, sound falls off less with distance than it does in open space, because rooms reflect it.
Very few makers state a distance. In our research:
- Levoit says its Superior Studio humidifier's 19 to 45 dB was measured 1.5 m from the unit.
- Campbell Hausfeld lists one quiet compressor at 68 dBA at 3 ft.
- Milwaukee rates its M18 FUEL blower at 54 dB(A) at 50 feet.
Of the 16 air compressors in our catalog, Campbell Hausfeld's DC080500 is the only one with a stated distance. So a compressor listed at 60 dB is not necessarily quieter than its 68 dBA at 3 ft. Our air compressor guide quotes each of those 16 figures in the maker's own words, with whatever distance or standard it gave.
OSHA gives the rule for open space: every doubling of distance from a point source takes 6 dB off the sound pressure level. Moved from 3 ft to 6 ft, Campbell Hausfeld's 68 dBA would be about 62, and at 12 ft about 56, if the compressor sat in open air.
The calculator below compares two figures by the 10 dB and 3 dB rules, and moves a figure from one distance to another by that 6 dB rule.
The distance half only works when the first distance is known. California Air Tools lists its 8010 at "60 dB Noise Level" with no distance, so there is nothing to move it from, and indoors the walls slow the fall-off below 6 dB.
The same goes for a reading you take yourself. Our guide to measuring noise at home explains why a phone reading will not match the maker's figure, and how to take readings at a fixed distance that you can compare with each other.
3. Sound pressure or sound power?
Most figures are sound pressure: what a microphone picks up at one spot. Some, often on European spec sheets, are sound power: the total sound a machine gives off, wherever you stand.
Sound power figures tend to be much higher numbers. Husqvarna's 110 dB(A) sound power and its 71 dB(A) bystander figure describe the same blower.
Liebherr's wine fridges show the European style: a figure "according to EN 60704-3", the method behind European energy labels. It is useful, but it cannot be set beside another maker's bare number.
4. Which standard?
A standard fixes all of the above: setting, distance, room and equipment. When two makers use the same standard, their figures can be compared. Some standards we have seen cited:
- ANSI B175.2 for leaf blowers, measured at 50 feet
- ISO 22868 for sound at the operator's ear on outdoor power tools
- EN 60704-3 for household appliance noise in Europe
But most makers name no standard at all. Of the 36 wine fridges in our catalog, 7 name one, and all 7 are Liebherr models declared under EN 60704-3. Our wine fridge guide notes which makers name a standard and which say the figure came from their own test.
How often do makers state a distance or a standard?
Noise figures rarely come with a distance or a standard, except on leaf blowers. We went through every product in five catalogs and counted how many figures arrive with a stated distance, a cited test method, or both. These figures describe our own catalog as it stood on October 26, 2026, not the whole market.
| Catalog | Products | States a distance | Names a test standard |
|---|---|---|---|
| Air purifiers | 84 | 4 | 4 |
| Humidifiers | 32 | 2 | 0 |
| Air compressors | 16 | 1 | 0 |
| Wine fridges | 36 | 1 | 7 |
| All four | 168 | 8 | 11 |
A figure counts if the maker gives the distance or standard on its own page, manual or spec sheet. Words such as "lab tested" or "internal testing" without a method do not count as a standard.
Who states them
In air purifiers, all 4 distances come from IQAir, which gives its HealthPro Plus as "Sound pressure (at 3.3 ft distance)". IQAir also names EN ISO standards on 3 models, and Blueair's DustMagnet manual cites GB/T18801, a Chinese air purifier standard.
Two Levoit Superior Studio humidifiers name 1.5 m, and one Ca'Lefort beverage cooler says its figure was "measured at one meter". The 7 wine fridge standards are all Liebherr's EN 60704-3 declarations.
Leaf blowers: the shared standard
Leaf blowers turn the pattern around. Of the 44 in our catalog, 28 carry a bystander figure under ANSI B175.2, the method that measures at 50 feet. They come from STIHL, ECHO, Husqvarna, Milwaukee, Makita and EGO.
Of the other 16, 10 print a US figure with no distance or standard, such as RYOBI's "Noise Rating" of 59 dB. Five give only figures at the operator's ear or sound power, and ECHO's DPB-5800T has no figure at all.
That is why our leaf blower guide can rank 28 models against each other and keeps the rest apart.
How do you spot a weak decibel figure?
Look for four warning signs built into the figure: a ceiling instead of a number, a bare range, two figures on one page, and dB with no A.
A ceiling, not a number
"Under 38 dBA" or "less than 41 dB" tells you the maker's figure is below a line, not what it is.
A figure described as "as low as 26 dB" is the quietest setting, by definition.
A bare range
"20 to 40 dB" with no labels leaves you to guess which end is which.
Two figures on one page
Summit's page for one wine fridge gives 32.4 dB in its spec table and 32.2 dB in its feature text. Makers sometimes disagree with themselves.
dB with no A
A-weighted figures, written dBA or dB(A), are adjusted to match how people hear. Plain dB leaves that unstated. See dBA explained for more.
Which noise comparisons can you trust?
Four comparisons hold up better than the rest: figures measured to the same standard, certified sone ratings, figures within one brand, and the same setting across brands.
Figures measured to the same standard
Leaf blowers are the best example. STIHL, Milwaukee, Makita and ECHO publish figures under ANSI B175.2, the 50 foot bystander method, so those numbers line up.
STIHL lists its BGA 30 at 50 dB(A) "Sound pressure level 15 m distance", and Milwaukee lists its M18 FUEL 3017-20 at 54 dB(A) as a 50 ft bystander figure. Both cite ANSI B175.2, so the 4 dB gap means something: about 2.5 times the sound energy, and roughly 1.3 times as loud to a neighbor.
Cities rely on this too. Portland, Oregon keeps a list of leaf blowers at 65 dBA or quieter at 50 feet, certified using ANSI methodology. That 50 foot figure is the one our quietest leaf blowers ranking is built on.
Certified sone ratings
Sones are the unit on bathroom fan and range hood boxes, and the Home Ventilating Institute certifies fan ratings. See sones vs decibels.
Figures within one brand
A maker probably measures its own range the same way, so its figures show the steps between models. Bosch, for example, lists its dishwashers at 48, 44 and 42 dBA as the price rises. Across brands, our dishwasher guide flags the figures that mean something different, such as Miele's sound power figure.
The same setting across brands
If two makers both label a figure as the low speed, or both as the highest speed, the comparison is fairer, though still not exact.
How do our guides handle noise figures?
Across our guides, a decibel or sone rating appears as the maker wrote it, along with whatever setting, distance or standard came with it. Where the maker gives none, we say "basis not stated".
We rank on published figures, but we treat small gaps between brands as uncertain, and we say so. Where a category has a shared standard, like leaf blowers, we rank only on that.
How do you compare two decibel ratings?
Check that both figures were measured the same way before you trust a gap between them. Ask:
- Do both describe the same setting?
- Do both give a distance, and is it the same?
- Are both sound pressure, or both sound power?
- Do both name the same standard?
- Is the figure a real number, or "under" or "as low as"?
If the answer to most of these is "not stated", treat a gap of a few decibels as no gap at all.
To decide what level to aim for, see how quiet is quiet enough, room by room. To see where published figures sit beside everyday sounds, keeping the same cautions in mind, see our decibel chart.
