## How to calculate decibels1 min read

Reading Time: < 1 minutesHow to calculate decibels

The decibel (dB) is a unit used to measure the intensity of sound. It is often abbreviated as dB. To calculate the dB level of a sound, you need to know the sound pressure level (SPL) and the reference point.

The SPL is the sound pressure of the noise or sound wave. It is measured in pascals (Pa) or millimetres of mercury (mmHg). The reference point is the threshold of hearing. The threshold of hearing is the level of sound that a person can hear 50% of the time. The dB level is the difference between the sound pressure and the threshold of hearing.

The following equation can be used to calculate the dB level:

dB = 20 × log (pressure/reference)

So, if the SPL is 100 Pa and the reference point is 0 Pa, the dB level would be 20. If the SPL is 1 Pa and the reference point is 0 Pa, the dB level would be 120.