Signal to Noise Ratio Calculator

Signal-to-Noise Ratio (SNR)

SNR compares desired signal strength to unwanted noise. Higher SNR means cleaner measurements in audio, RF, imaging, and data acquisition. Engineers express SNR in decibels for convenient logarithmic scaling.

Power and Amplitude Forms

$$\text{SNR}_{\text{dB}} = 10 \log_{10}\!\left(\frac{P_{\text{signal}}}{P_{\text{noise}}}\right)$$ $$\text{SNR}_{\text{dB}} = 20 \log_{10}\!\left(\frac{A_{\text{signal}}}{A_{\text{noise}}}\right)$$

Use the 10 log form for power ratios. Use the 20 log form for voltage or amplitude ratios because power scales with amplitude squared.

Worked Example

Signal power 10 W and noise power 0.1 W gives a ratio of 100. Then $\text{SNR} = 10 \log_{10}(100) = 20$ dB.

Related tools: Noise Figure Calculator and Resistor Noise Calculator.

Frequently Asked Questions

When do I use 10 log versus 20 log?

Use 10 log₁₀ for power ratios. Use 20 log₁₀ for amplitude or voltage ratios when power is proportional to amplitude squared.

What is a good SNR value?

It depends on the application. Audio often targets 60 dB or higher. RF receivers may operate at 10 to 20 dB SNR depending on modulation and coding.

Can SNR be negative?

Yes. Negative SNR in dB means noise exceeds signal. The linear ratio is then less than one.

Is SNR the same as dynamic range?

Not exactly. SNR compares signal to noise at a given moment. Dynamic range describes the span between largest and smallest distinguishable levels in a system.

How does SNR relate to noise figure?

Noise figure quantifies how much an amplifier degrades SNR. NF = SNR_in − SNR_out in dB for linear two-port devices.

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Signal to Noise Ratio Calculator

Signal-to-Noise Ratio (SNR)

Power and Amplitude Forms

Worked Example

Frequently Asked Questions

Related Tools

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