Signal-to-Noise Ratio (SNR) Calculator
Convert a signal-to-noise ratio into decibels. Enter the signal and noise levels in the same units — the calculator uses the power formula (10·log₁₀) or amplitude/voltage formula (20·log₁₀) depending on the measurement type.
Measurement type
Higher dB = cleaner signal; 0 dB = signal equals noise
- 1
Linear ratio S/N
100 ÷ 5 = 20 - 2
SNR = 10·log₁₀(S/N)
10 × log₁₀(20) = 13.01Power formula: factor of 10 because power is proportional to amplitude².
How does this calculator work?
SNR in decibels = 10·log₁₀(signal power / noise power) for power measurements, or 20·log₁₀(signal amplitude / noise amplitude) for voltage. A result above 0 dB means the signal beats the noise; values of 20–40 dB or higher are typical targets for clean audio and reliable communications.
Formula
How this is calculated
Signal-to-noise ratio (SNR) measures how much stronger a desired signal is compared to the background noise. It is expressed in decibels (dB) because the range of signal and noise levels encountered in engineering, audio, and communications spans many orders of magnitude. A positive SNR means the signal is stronger than the noise; 0 dB means they are equal; a negative value means the noise dominates.
The formula depends on whether you are working with power quantities (measured in watts, milliwatts, or dBm) or amplitude/voltage quantities (measured in volts, pascals, or similar). For power: SNR = 10·log₁₀(P_signal / P_noise). For voltage or amplitude: SNR = 20·log₁₀(V_signal / V_noise). The factor of 20 instead of 10 arises because power is proportional to the square of amplitude, and log(x²) = 2·log(x).
Practical reference points: ≥40 dB is considered excellent quality (negligible noise) in audio; 20–40 dB is adequate; below 10 dB the noise is audible or the signal is marginal. In digital communications a minimum SNR is required to meet a target bit-error rate. Always ensure signal and noise values are measured in the same units and at the same reference point for a meaningful result.
Frequently asked questions
Use 10·log₁₀ when you have power quantities (watts, dBm, milliwatts). Use 20·log₁₀ when you have amplitude or voltage quantities (volts, pascals, microvolts). The factor of 20 accounts for the fact that power is proportional to the square of amplitude.
It depends on the application. In audio, ≥ 40 dB is typically imperceptible noise. In Wi-Fi, ≥ 25 dB provides a reliable connection. In radio communications, the minimum acceptable SNR is set by the modulation scheme and required bit-error rate. Higher is always better — more headroom means more tolerance for interference.
Increase the signal (stronger transmitter, better antenna gain, higher microphone gain) or reduce the noise (shielding, filtering, lower-noise amplifiers, averaging multiple measurements). Moving the signal source closer to the receiver is often the simplest fix.
Also known as
TG we-Calculate Editorial Team. (2026). Signal-to-Noise Ratio (SNR) Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/signal-to-noise-ratio-calculator
TG we-Calculate Editorial Team. "Signal-to-Noise Ratio (SNR) Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/signal-to-noise-ratio-calculator.
TG we-Calculate Editorial Team, "Signal-to-Noise Ratio (SNR) Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/signal-to-noise-ratio-calculator
@misc{wecalculate_signal_to_noise_ratio_calculator, title = {Signal-to-Noise Ratio (SNR) Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/signal-to-noise-ratio-calculator}}, year = {2026}, note = {TG we-Calculate} }
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