The decibel is a logarithmic way of expressing a ratio between two quantities, which is why it appears everywhere in audio, radio and signal processing. For a power ratio the decibel value is ten times the base ten logarithm of the ratio, while for an amplitude or voltage ratio it is twenty times that logarithm, because power scales with the square of amplitude. This calculator converts a ratio into decibels and also converts a decibel figure back into the corresponding power and amplitude ratios. That lets you reason about gains and losses, for example seeing that a doubling of power is close to three decibels and a doubling of voltage is close to six. Choose your direction, enter a value, and the result appears instantly, all computed locally in your browser.
For power ratios it uses 10 times log base 10 of the ratio, and for voltage or amplitude ratios it uses 20 times log base 10 of the ratio.
Power scales with the square of amplitude, so the log of an amplitude ratio is doubled, giving 20 instead of 10.
Yes. Enter a decibel value and it returns the equivalent power or amplitude ratio.
The decibel is a logarithmic way of expressing a ratio between two quantities, which is why it appears everywhere in audio, radio and signal processing. For a power ratio the decibel value is ten times the base ten logarithm of the ratio, while for an amplitude or voltage ratio it is twenty times that logarithm, because power scales with the square of amplitude.
Yes. Decibel (dB) Calculator is completely free, with no sign-up and no usage limits.
Yes. Decibel (dB) Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Decibel (dB) Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.