Decibel Calculator
Enter the known values and run the calculation.
Use the 10 log10 relationship for power ratios.
Choose whether you are working with a power ratio, an amplitude ratio, or an inverse conversion from dB back to linear.
Enter the known value, run the calculation, and use the result card to see the matching dB term plus the equivalent power and amplitude interpretations.
Overview
Convert ratios into dB so gain, attenuation, and relative power numbers can be compared quickly.
Use this tool to move between linear ratios and logarithmic dB terms when you need to compare gain, attenuation, or relative level changes quickly.
It is useful in RF, audio, and general signal-chain work where one person thinks in ratios and the next person thinks in dB.
The math and how it's used
Use the power form when the quantity is genuinely a power ratio.
Use the amplitude form for voltage or current ratios when both sides share the same impedance reference.
Inverse forms are P2/P1 = 10^(dB/10) and V2/V1 = 10^(dB/20).
The 10 log10 form is for power ratios. The 20 log10 form is for voltage or current ratios only when the impedance reference is unchanged between the two conditions.
If impedance changes between the two points, convert back to power first instead of assuming the amplitude form is still valid.
This tool is for moving between linear ratios and the dB language that shows up in gain budgets, attenuation specs, and instrument readouts.
Use the power form when the ratio represents power and the amplitude form when it represents voltage, current, or field magnitude into the same impedance. Mixing those interpretations is where bad dB math usually starts.