Signal-to-Noise Ratio Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Small input changes can produce surprisingly large shifts in signal-to-noise ratio, especially when squared terms or angles are involved. For signal-to-noise ratio, energy and power numbers are easiest to understand when you keep track of what is being stored, transferred, or normalized. This page converts the entered quantities into one focused result without adding unrelated assumptions.

What this calculator does

This calculator compares signal with noise in either power or amplitude mode and reports both a linear signal-to-noise ratio and its decibel equivalent.

How to use it

Start with the fields that drive the current calculation: Signal power, Noise power. Enter values in the units shown beside each field; the page converts supported units before applying the formula. If you change Calculate SNR using, check that the newly selected method matches the quantities you intend to solve. Keep signs and angles consistent with the labels, then read the headline result together with any supporting metrics rather than copying the number without its unit.

How the calculation works

In power mode, the linear ratio is Ps/Pn and SNRdB = 10 log10(Ps/Pn). In amplitude mode, the page squares the amplitude ratio before applying 10 log10, which is equivalent to 20 log10(As/An). The headline is the linear ratio; dB appears as a supporting result.

Example

With signal power 10 and noise power 1, the power ratio is 10. The page therefore headlines a linear SNR of 10 and shows 10 dB as the supporting logarithmic value. Those are two representations of the same signal-to-noise relationship, not two different measurements.

How to interpret the result

A larger linear ratio or dB value means the signal is stronger relative to the noise. A ratio of 10 in power corresponds to 10 dB; 100 corresponds to 20 dB. Whether a given SNR is adequate depends on the measurement, communication system, bandwidth, and performance target.

Limitations and notes

The page assumes compatible signal and noise measurements. Use power with power, or matching amplitude quantities with the same impedance context. The headline is a linear ratio, not dB; read the supporting SNR value for decibels.