Enter the total signal (volts) and total noise (volts) into the calculator to determine the SNR (signal-to-noise ratio).

SNR Formula

The following formula is used to calculate the signal-to-noise ratio (SNR). 

SNR = 20*log(S / N)

SNR = 20*log10 (S / N)

  • Where SNR is the signal to noise ratio (decibels, dB)
  • S is the signal (volts)
  • N is the noise (volts)

The units for signal and noise could be different, for example, millivolts, as long as the units are the same for each variable.

SNR Example Problem

How to calculate SNR?

  1. First, determine the signal strength.

    In this example, the signal strength is measured to be 45 volts.

  2. Next, determine the noise strength.

    For this problem, the noise is measured to be 3.5 volts.

  3. Finally, calculate the signal-to-noise ratio (SNR).

    Using the formula above, the SNR is calculated to be:
    SNR = 20*log10 (S / N)
    SNR = 20*log10 (45 / 3.5)
    SNR = 22.182