Use this decibel calculator to answer the two questions a spec sheet raises most often: how much louder is one model than another, and what does a figure measured up close become at your chair? Both calculators run on arithmetic published by the National Park Service and OSHA, not on rules of our own. Type the figures from the spec sheets and read the result in plain words.
How do you compare two decibel figures?
Enter both figures in the first calculator below, and it reports the gap three ways: in decibels, in sound energy and in perceived loudness. The second calculator takes one figure plus two distances and estimates the level where you actually sit.
What do the loudness results mean?
Decibels grow on a logarithmic scale, so a small gap in the number hides a large gap in energy. The National Park Service puts the two key rules in one line each: an increase of 10 dB is perceived as about twice as loud, and an increase of 3 dB doubles the sound energy while being barely noticeable.
Both rules appear in the result. A 44 dBA dishwasher against a 50 dBA one shows a 6 dB gap: four times the sound energy, and roughly one and a half times as loud to your ear. That framing is usually more useful than the bare numbers when two models sit close together.
How does distance change a decibel figure?
Sound pressure falls as it spreads, and in open space the drop follows a simple rule: about 6 dB for every doubling of distance, per OSHA's technical manual. A fan rated at 1 meter is quieter by the time the sound crosses a bedroom.
The second calculator applies that rule. Give it the published figure, the distance the maker measured at, and the distance you care about. Indoors the estimate is a floor rather than a promise, because reflected sound off walls and furniture raises the level above the open-space value.
Makers rarely state their measuring distance at all. Across the catalogs behind our guides, stated distances are the exception, which is why our pages quote the condition whenever one exists.
When is a decibel comparison unfair?
No calculator can rescue two figures measured under different conditions. Before comparing, check four things on the spec sheets: the weighting (dBA against plain dB), the setting (lowest speed against highest), the distance, and whether either figure is sound power rather than sound pressure. Comparing decibel ratings walks through each trap with real models.
Weighting matters because a dBA figure is filtered to match human hearing, as dBA explained covers. Settings matter because a fan's lowest speed can sit 20 dB or more below its highest. And sones, the loudness unit on bathroom fans and range hoods, never convert to decibels at all; see sones vs decibels for how to read them.
How did we build these calculators?
The calculators implement the agency arithmetic cited above. The National Park Service supplies the loudness and energy rules, and OSHA's technical manual supplies the distance rule. We did not measure anything ourselves, and the calculators never compare figures for you; they only translate the gap you give them. The maker figures shown further down this page come from our buying guides, each quoted with the condition the maker printed.
