Decibel (Sound Level) Calculator
Calculate sound pressure level in decibels from sound intensity.
Assumptions used in this calculation
- Reference intensity: Uses the standard reference intensity of 10⁻¹² W/m², the accepted threshold of human hearing at 1 kHz.
About this calculator
Sound intensity measured in watts per square meter is a physically meaningful number but not a useful one for humans, our hearing spans such an enormous intensity range that a linear scale would be unwieldy, which is why sound is reported in decibels instead. This calculator converts a raw sound intensity value into decibels using the logarithmic formula dB = 10 × log₁₀(I ÷ I₀), where I₀ is the standard reference intensity of 10⁻¹² W/m², the accepted threshold of human hearing. Enter a sound intensity and it returns the equivalent decibel level directly, without you needing to compute a base-10 logarithm by hand. Because the scale is logarithmic, small differences in decibel readings represent large differences in actual intensity, every 10 dB increase corresponds to a tenfold increase in intensity, though it's perceived by human hearing as roughly a doubling in loudness, a distinction that's easy to miss without doing the actual math. This is useful for converting lab or sensor intensity readings into the decibel figures used in noise regulations and hearing safety guidelines.
Worked example
0.001 W/m² (busy street traffic)
Result: 90 dB
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