Amplitude To Decibel Converter
Convert an amplitude ratio into decibels as 20 × log10(value / reference).
Open toolDecibel Calculator
Find a power ratio in decibels as 10 × log10(value / reference). Both powers must be positive and in the same unit.
Free to useNo sign-upRuns in your browser
Enter your details
Enter the inputs, then select Calculate.
Your result
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Result will appear here
How Decibel Calculator works
Find a power ratio in decibels as 10 × log10(value / reference).
Both powers must be positive and in the same unit. This is a power ratio, not an amplitude ratio or calibrated sound level. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
How to use Decibel Calculator
Follow the labelled inputs.
Enter power value
Replace the example with power value. The field labels specify the expected format and units.
Input and settings
Check the remaining inputs
Set reference power in the same unit. Both powers must be positive and in the same unit.
Tool result
Run, review and save
Select Calculate. Review the calculated result, then copy it or download the result text.
Review the details
Examples and uses for Decibel Calculator
Check the supplied example
The starting example produces 20 dB. Find a power ratio in decibels as 10 × log10(value / reference).
Use your own inputs
Read the labels for power value and reference power in the same unit. Both powers must be positive and in the same unit.
Record a reviewed result
Copy the calculated result into your notes. Keep the formula and assumptions with it if someone else needs to reproduce the calculation.
How to read the result
Read the units and assumptions with the output.
Find a power ratio in decibels as 10 × log10(value / reference).
Both powers must be positive and in the same unit. This is a power ratio, not an amplitude ratio or calibrated sound level. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
Supported input and limits
Check the stated scope before you run it.
Both powers must be positive and in the same unit. This is a power ratio, not an amplitude ratio or calibrated sound level. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
The input stays in this browser. Copy result and Download save the same displayed text.
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Open toolDecibel Calculator: common questions
Answers about using Decibel Calculator and understanding its results.
What assumptions and input limits apply?
Both powers must be positive and in the same unit. This is a power ratio, not an amplitude ratio or calibrated sound level. Finite real inputs; output uses up to 12 significant digits. Floating-point results may be rounded.
How can I save the output?
Use Copy result to copy the displayed text, or Download to save it as a text file. The tool runs in your browser and does not require an account.
Calculate with your input
Check the calculated result, then copy or download it.