Decibel Calculator
Ratios
Enter the two levels; choose whether they're power or voltage.
Result
How to use this calculator
The decibel is a logarithmic ratio. For power use dB = 10·log₁₀(P₂/P₁); for voltage across the same impedance use dB = 20·log₁₀(V₂/V₁). Enter two levels and pick the quantity, and the dB difference, the linear ratio, and the linear power ratio appear live. Common anchors: +3 dB ≈ double the power, +6 dB ≈ 4× power, −3 dB ≈ half power.
What it means in a real circuit
dB is the language of audio and RF: amplifier gain, cable loss, pad depth, and system headroom are all quoted in dB. Because it's logarithmic, a 10 dB gain means 10× power, and you can add/subtract stages arithmetically instead of multiplying. Use this to size gain and loss in a signal chain, or to convert a measured voltage ratio into an equivalent dB figure.