Calculate decibels for sound pressure level, sound intensity level, power gain, voltage gain, and sound level change over distance. Enter your values to see the dB result, formula, category, and calculation steps.
Sound pressure level:
Uses pressure compared with a reference pressure. In air, the common reference is 20 micropascals.
Power and intensity:
Power and intensity ratios use 10 × log10 because they compare energy-style quantities.
Voltage and pressure:
Voltage and pressure ratios use 20 × log10 when the comparison is based on amplitude.
A decibel calculator helps convert sound, power, voltage, and distance changes into dB values. This is useful for acoustics, audio systems, speakers, microphones, noise checks, engineering, and sound comparisons.
Decibels are logarithmic, so a small dB change can represent a much larger change in sound pressure, intensity, or power ratio.
A decibel is a logarithmic unit used to compare ratios. It is commonly used for sound levels, audio gain, power changes, and signal levels.
dB SPL means decibels sound pressure level. In air, it commonly uses 20 micropascals as the reference pressure.
Power and intensity ratios use 10 × log10. Pressure and voltage ratios use 20 × log10 because they are amplitude-style quantities.
In ideal free field conditions, doubling the distance from a point sound source reduces the level by about 6 dB. Real rooms, reflections, barriers, and directionality can change the result.