Sound Level Converter

Convert sound and signal levels between decibels, bels, nepers and centibels.

How to use the Sound Level Converter

  1. Type the value you want to convert in the first box.
  2. Choose the unit you are converting from and the unit you want to convert to.
  3. Read the result instantly. Use the swap button to reverse the direction, or copy the result with one click.

Popular sound level conversions

ConversionResultFormula
Decibels to nepers1 dB = 0.115129 Npnepers = decibels × 0.11512925
Nepers to decibels1 Np = 8.68589 dBdecibels = nepers × 8.6858896
Decibels to bels1 dB = 0.1 Bbels = decibels ÷ 10
Bels to decibels1 B = 10 dBdecibels = bels × 10

Supported sound level units

UnitSymbolEqual to
DecibeldB1 dB
BelB10 dB
NeperNp8.6858896 dB
CentibelcB0.1 dB
MillibelmB0.01 dB

How decibels work

The decibel is a logarithmic unit: it expresses the ratio between two levels instead of an absolute amount. An increase of 10 dB means ten times the sound power, and is heard as roughly twice as loud. An increase of 3 dB doubles the power.

A bel is 10 decibels. The neper does the same job using natural logarithms and is used in telecommunications: 1 Np ≈ 8.686 dB.

Sound Level (dB SPL)
Threshold of hearing 0
Whisper 30
Normal conversation 60
Busy traffic 80–85
Rock concert 110
Jet engine nearby 130–140

Long exposure above about 85 dB can damage hearing.

Frequently asked questions

How many decibels are in a bel?

One bel equals 10 decibels.

How do I convert nepers to decibels?

Multiply nepers by 8.686. One neper is about 8.686 dB.

How much louder is 10 dB?

A 10 dB increase is ten times the sound power and sounds roughly twice as loud to most people.

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