Signal-to-Noise Ratio Calculator

Calculator Inputs

Choose a mode, then enter values and units.

Calculation mode

Additional gain / processing gain (dB)

Optional: add filtering, averaging, or system gain in dB.

Tip: Keep all measurements in the same bandwidth and reference.

Power inputs

Signal power

Signal power unit

Noise power

Noise power unit

Bandwidth (optional)

Adds noise spectral density outputs if set.

Bandwidth unit

Voltage or current inputs

Measurement type

Assumes same impedance for both values.

Impedance (ohms)

For voltage/current ratios: SNR(dB) uses 20·log10(ratio).

Signal voltage (RMS)

Signal voltage unit

Noise voltage (RMS)

Noise voltage unit

Signal current (RMS)

Signal current unit

Noise current (RMS)

Noise current unit

Convert SNR

Conversion direction

SNR value

Use dB for the first option, linear for the second.

Solve for unknown power

Solve for

Known power value

Known power unit

SNR value

SNR scale

Example data table

Use these values to test each mode quickly.

Scenario	Signal	Noise	Expected SNR (linear)	Expected SNR (dB)
Power ratio	10 mW	10 µW	1000	30 dB
Voltage ratio (same R)	0.2 V RMS	0.01 V RMS	400	26.0206 dB
Convert	20 dB		100	20 dB

Note: Voltage/current dB uses 20·log10(ratio), while power uses 10·log10(ratio).

Formula used

Power ratio: SNR = P_s / P_n
Power in decibels: SNR(dB) = 10·log10(P_s/P_n)
Voltage/current ratio (same impedance): SNR(dB) = 20·log10(V_s/V_n) and SNR = (V_s/V_n)²
From RMS voltage to power: P = V² / R
From RMS current to power: P = I² · R
Optional gain: SNR(dB)_total = SNR(dB)_base + gain(dB)

All logarithms are base-10. Use consistent measurement bandwidth and reference conditions.

How to use this calculator

If you see unexpected results, re-check unit choices, RMS vs peak values, and whether your signal and noise share the same bandwidth.