Signal-to-Noise Ratio Calculator
The signal-to-noise ratio (SNR) calculator computes the ratio of useful signal strength to background noise level in decibels. SNR is a universal quality metric used in audio engineering, telecommunications, wireless networks, medical imaging, and scientific instruments. A high SNR indicates that the desired signal dominates over interference and noise, while a low or negative SNR means the signal is buried in noise. This tool lets you enter signal and noise values as either power (watts) or voltage (volts) and calculates the SNR in dB. You can also reverse-calculate: enter an SNR value to find the required signal level given a known noise floor. Understanding SNR is critical for designing reliable data links, audio systems, and measurement equipment.
SNR formulas
Power SNR (dB) = 10 * log10(P_signal / P_noise)
Voltage SNR (dB) = 20 * log10(V_signal / V_noise)
Linear ratio = P_signal / P_noise
SNR quality benchmarks
- Below 0 dB: noise exceeds signal (unacceptable for most uses).
- 0 to 10 dB: very poor, audio barely intelligible.
- 10 to 25 dB: acceptable for voice communications.
- 25 to 40 dB: good quality for music and data links.
- Above 40 dB: excellent; required for high-fidelity audio and high-speed data.
- Above 60 dB: studio quality audio or precision instrument measurements.
SNR: frequently asked questions
What is signal-to-noise ratio?
Signal-to-noise ratio (SNR) is the ratio of desired signal power to background noise power. A higher SNR means the signal is much stronger than the noise, producing clearer audio, better image quality, or more reliable data communication. SNR is almost always expressed in decibels (dB).
How is SNR calculated?
SNR (dB) = 10 * log10(P_signal / P_noise) for power quantities, or SNR (dB) = 20 * log10(V_signal / V_noise) for voltage quantities. An SNR of 0 dB means signal and noise are equal. Positive dB means the signal is stronger than the noise.
What is a good SNR?
For audio recording, 60 dB or higher is considered good. For digital communications, the required SNR depends on the modulation scheme: BPSK needs around 10 dB for reliable reception, while 256-QAM requires 30 dB or more. In medical imaging, SNR directly affects diagnostic image quality.
What is the difference between SNR and SINAD?
SINAD (Signal to Noise and Distortion) includes both noise and harmonic distortion in the denominator. SNR only measures noise. SINAD is used to evaluate the quality of analog-to-digital converters (ADCs), where distortion products are as important as noise floor.
How do I improve SNR?
SNR can be improved by increasing signal power (higher transmit power, better antenna gain), reducing noise (lower receiver noise figure, cooling, shielding), filtering out out-of-band noise with bandpass filters, or using signal averaging for repeated measurements.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.