Sones to dBA Estimate Calculator
Approximate A-weighted sound level from a sone rating.
Enter your values
ⓘ Live results
Results
- Estimated sound level
- 59.4 dBA
- Perceived loudness
- Quiet bathroom fan
Quick answer
As a rule of thumb, dBA is approximately 33.2 times the log base 2 of sones, plus 40, though the exact relationship depends on spectrum.
dBA ~ 40 + 33.22 x log2(sones)
How to use the Sones to dBA Estimate Calculator
- 1Enter the fan's sone rating from its spec sheet (bath fans are commonly rated 0.5-4 sones).
- 2Read the approximate equivalent A-weighted decibel level.
- 3Use as a rough guide only — true dBA depends on the frequency spectrum of the specific fan.
Worked example
Using the values the calculator loads with:
Inputs
- Fan sone rating1.5 sones
Results
- Estimated sound level59.4 dBA
- Perceived loudnessQuiet bathroom fan
Frequently asked questions
Why is this only approximate?
Sones measure perceived loudness while dBA measures pressure with frequency weighting; the two scales relate non-linearly and depend on spectral content.
What sone rating is 'quiet' for a bath fan?
1.0 sone or less is generally considered quiet for residential bathroom fans.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.