Signal-to-Noise Ratio (SNR) measures how much stronger the desired signal is compared to background noise. It is expressed in decibels (dB): SNR = 10 × log₁₀(P_signal / P_noise).

What is a good SNR value?

For Wi-Fi, ≥25 dB is considered good and ≥40 dB is excellent. For audio or RF links, requirements vary by application, but higher is always better.

What units can I use?

You can enter power in watts (W), milliwatts (mW), or dBm. When using dBm, SNR is computed as the difference: SNR = signal_dBm − noise_dBm.

What does a negative SNR mean?

A negative SNR means the noise power exceeds the signal power. The signal is buried in noise and is generally unusable without advanced error correction.

What is the difference between SNR and RSSI?

RSSI (Received Signal Strength Indicator) measures signal strength alone, while SNR compares signal strength to noise. SNR is a better indicator of link quality.

Signal-to-Noise Ratio Calculator

Name: Signal-to-Noise Ratio Calculator
Availability: InStock
Author: Nham Vu

Enter signal and noise power values to compute SNR in dB and see a quality rating.

SNR Inputs

Input Unit

Signal Power (W)

Noise Power (W)

Formula Reference

W / mW SNR (dB) = 10 × log₁₀(P_signal / P_noise)

dBm SNR (dB) = P_signal − P_noise

Enter signal and noise values, then click Calculate.

Summary

Enter signal and noise power values to compute SNR in dB and see a quality rating.

How it works

Select an input unit (W, mW, or dBm).
Enter signal power and noise power values.
The tool applies SNR = 10 × log₁₀(P_signal / P_noise) for linear units, or SNR = signal_dBm − noise_dBm for dBm.
The result in dB is displayed with a color-coded quality band.

Use cases

Evaluate Wi-Fi signal quality relative to interference.
Assess audio or RF link budgets during system design.
Check whether a received signal meets a minimum SNR threshold.
Compare signal quality across different antenna placements.
Verify cable or fiber link margins in network planning.
Diagnose poor streaming or VoIP call quality caused by low SNR.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu