Percent to dB Calculator

This tool converts from Percentage (%) to deciBel (dB)

dB to Percent

Formula

A_dB = 10*Log₁₀(A_%/100)

Background

The dB scale is very useful for the representation of large numbers. For instance the number 1000000000 is equivalent to 90 dB.

dB represents the ratio between two amplitudes or powers. For instance the ratio between the output and input of an amplifier or RF attenuator block can be expressed in dB.

In general we might say that an attenuator reduces an input signal by 50%.

What’s that in dB?

That’s where this calculator comes in. In this case, 50% is equivalent to -3 dB.

In general if the amplitude of a signal at the output of a module is a percentage number between 0 and 100%, it represents a reduction and consequently the dB value is negative.

If the percentage value exceeds 100%, the dB value is positive. This is usually the case for an amplifier. Typical values of amplification are 1000% which equates to 10 dB.

Example Calculation

1% represents a linear value of 0.01 and equates to -20 dB.

0% results in logarithm of zero. The dB equivalent is a very small number represented as -Inf.

Percent to dB Chart