DECIBEL (dB) CONVERTER


Decibel (dB) converter is a online tool for decibel - ratio conversion, multiplication of dB value by a number and addition and subtraction operations of values in dB. Formulas for dB calculations such as decibel field ratio calculation, decibel power ratio calculation, adding decibels, subtracting decibels and multiplication of decibel by a number are given in the "List of Equations" section of this page.


Calculator:

dB - Ratio conversion
Magnitude type
 Conversion type
Ratio (factor) Decibel
   
 Multiplication by a number (n * B(dB) = A(dB))
Relationship n B  (dB) A (dB)
     
Addition / Subtraction (LA(dB) ± LB(dB) = Result)
Relationship LA (dB) LB  (dB) Result
     

Note: Use dot "." as decimal separator.



Definitions:

Decibel (dB): Decibel is a unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels.

Examples to power quantities: Sound power measurements, power spectral density random vibration.

Examples to field quantities:  Voltage, displacement, velocity, acceleration, force, sound pressure, strain.

Reference  acoustic sound pressure level dB(SPL) : The lowest sound pressure which is usually considered the threshold of human hearing (at 1 kHz) is approximately 2*10-5Pa .

List of Equations:
 
The power relationship in dB The power relationship in dB
The field relationship in dB The field relationship in dB
Multiplication by a number n for power relationship dB Multiplication by a number n for power relationship
Multiplication by a number n for field relationship dB Multiplication by a number n for field relationship
Addition of dB Addition of dB
Subtraction of dB Subtraction of dB

Notes:

If P is greater than P0 then ratio is positive; if P is less than P0 then ratio is negative.

P is the measured power and P0 is the reference power.

A is the measured amplitude and A0 is the reference amplitude.

For addition and subtraction operation, LA ≥ LB condition shall be met.