🔊Decibels Converter

Convert between decibels and linear ratios for power and amplitude.

Ratio (linear)

Decibels (dB)

dB = 10 × log₁₀(ratio)

About Decibels Converter

Convert between decibels (dB) and linear ratios for both power and amplitude quantities. The decibel is a logarithmic unit expressing the ratio of two values. Power ratios use 10 × log₁₀(ratio) while amplitude ratios use 20 × log₁₀(ratio). Widely used in audio engineering, telecommunications, and acoustics.

How to Use Decibels Converter

1
Select mode
Choose power ratio (10 log) or amplitude ratio (20 log) based on your measurement type.
2
Enter a value
Type a linear ratio or a dB value in the appropriate field.
3
See the result
The converted dB or ratio value appears instantly.

Common Use Cases

Audio engineering gain and attenuation calculation
Telecommunications signal strength analysis
Acoustics and sound pressure level measurement
Electronics amplifier and filter design

Frequently Asked Questions

What is a decibel?

A decibel is one-tenth of a bel, a logarithmic unit expressing the ratio of two quantities. It is widely used to describe power levels, sound pressure, and signal gain in electronics and acoustics.

What is the difference between power and amplitude dB?

For power ratios, dB = 10 × log₁₀(ratio). For amplitude (voltage, pressure) ratios, dB = 20 × log₁₀(ratio), because power is proportional to amplitude squared.

What does 0 dB mean?

0 dB means the ratio is 1:1 — no gain or attenuation. Positive dB values indicate gain (amplification) and negative values indicate attenuation (reduction).