dB to Percentage Calculator

This tool converts from deciBel to a Percentage.

? Percent to dB

Formula

A_Linear = 10^A_dB/10

A_% = 100*A_Linear

Example Calculations

3 dB is a commonly used quantity in the world of RF engineering.

A two port device called a 3 dB splitter splits the input signal into two equal powered output signals. Use -3 dB in the calculator above. This gives a linear value of 1/2 or 0.5. Half the power appears on each output port. In percentage terms, the value is 50%. Essentially it is a halving of value.

A passive splitter may be used as an RF combiner. In this case, an equal amount of power on each input, e.g. +10 dBm, will result in a doubling of power to give +13 dBm on the output (using the RF combiner calculator) This is 3 dB higher. In percentage terms it’s 200%.

In the case of a lossless antenna cable, the input power is equal to the output power. There’s 0 dB of loss in this case which translates to 100% of the input being transferred to the output. Antenna cable loss can never be zero. It can however be very negligible for very short lengths and at low frequencies.

A 3 dB amplifier results in a doubling of the signal. In percentage terms, the value in this case is 200%.

It’s really important to consider the sign of the dB value. A negative sign implies a reduction in power relative to the original while a positive sign means an increase.

A 10 dB amplifier results in an output power that is ten times the input power. In percentage terms this is 1000%.

dB to Percent Chart

This is a table that shows dB values and their linear and percent equivalent from -100 dB to +100 dB.