Signal-to-Noise Ratio Calculator
The signal-to-noise ratio calculator compares signal power with noise power and expresses the ratio both as a plain number and in decibels.
How to use this calculator
- Enter positive signal and noise power values measured in the same units and under compatible conditions.
- Check the units and definitions before comparing results with another source.
- Change one input at a time when comparing scenarios, and keep the reporting period and assumptions consistent.
Formula used by the signal to noise ratio calculator
SNR = Psignal/Pnoise; SNR(dB) = 10 log₁₀(Psignal/Pnoise)
- SNR = Psignal/Pnoise; SNR(dB) = 10 log₁₀(Psignal/Pnoise)
- Both inputs must be comparable power measurements. An amplitude or voltage ratio uses a different logarithmic factor under compatible reference conditions.
- Inputs are checked for required values and valid ranges; displayed results are rounded for readability.
Worked examples
Worked example
Signal power is 100 units and noise power is 1 unit.
The power ratio is 100:1 and the SNR is 20 dB.
The power ratio is 100:1 and the SNR is 20 dB.
Understanding the result
The signal-to-noise ratio calculator compares signal power with noise power and expresses the ratio both as a plain number and in decibels.
Both inputs must be comparable power measurements. An amplitude or voltage ratio uses a different logarithmic factor under compatible reference conditions.
Important notes
Both inputs must be comparable power measurements. An amplitude or voltage ratio uses a different logarithmic factor under compatible reference conditions.
The result applies to the numbers and assumptions entered here; verify specifications for safety-critical or regulated uses.
Frequently asked questions
What does a positive SNR mean?
It means signal power exceeds noise power; a negative dB result would mean the entered signal power is below noise power.
Can voltage values be entered directly?
Not with the power formula unless they have been converted to compatible power values or the appropriate amplitude-ratio formula is used.
How do I use this calculator?
Enter positive signal and noise power values measured in the same units and under compatible conditions.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.