Sound Level Converter
Convert between decibels (dB), nepers (Np), and bels (B) for sound and signal levels.
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How to use this calculator
- 1
Enter the sound level value you want to convert.
- 2
Select the unit you are converting from (e.g. decibels).
- 3
Select the target unit (e.g. nepers).
- 4
The result appears instantly.
Frequently asked questions
How many decibels are in a bel?
Ten decibels make one bel: 1 B = 10 dB and 1 dB = 0.1 B. So 20 dB is 2 B, and 100 dB is 10 B. The decibel is the unit used in practice.
How are decibels and nepers related?
1 Np equals 8.685889638 dB, which is 20 divided by the natural log of 10, so 1 dB is 0.11512925 Np. The neper uses natural logarithms while the bel and decibel use base-10 logs. 20 dB is 2.302585093 Np.
Does this convert sound pressure into dB?
No. The tool relabels one logarithmic level unit in another. It does not turn pascals or watts into decibels. A level in dB SPL is measured against 20 micropascals in air, a reference that needs the original pressure.
Does it handle dBA or other weightings?
No. A-weighting, C-weighting and references such as dBm or dBV change the meaning of the number, not the unit. The converter only changes dB, B and Np for the same quantity.
Why can’t I just add decibel levels?
Decibels are logarithmic. Two identical incoherent sound sources of 60 dB together produce about 63 dB (a 3 dB rise), not 120 dB. Convert back to power or pressure before combining.
What do 3 dB, 6 dB, 10 dB and 20 dB mean?
A 10 dB rise is a tenfold power ratio, and 20 dB is a tenfold ratio in amplitude (voltage or pressure). About 3 dB doubles power and about 6 dB doubles amplitude. In bels, 3 dB is 0.3 B and 6 dB is 0.6 B.
Does 0 dB mean silence?
No. 0 dB means a ratio of one against the reference level, so nothing changes. On a dB SPL scale, 0 dB is the reference of 20 µPa, which is near the threshold of hearing for most people. Sounds below the reference have negative dB values.
Sound level units: decibels, bels and nepers
Ratios on a logarithmic scale
A decibel, a bel and a neper all describe a ratio between two quantities on a log scale. One bel is 10 decibels. One neper is 8.685889638 decibels, which is 20 divided by the natural log of 10, because the neper uses natural logarithms. So 1 dB is 0.1 B or 0.11512925 Np. The converter multiplies by these fixed relationships and nothing more. The scale compresses huge ranges into small numbers, which is why a 100 dB level and a 0 dB level differ by a power ratio of ten billion.
Reference values taken from the converter
Each row starts from a level in decibels and shows it in bels and nepers, copied from the tool’s output.
| Decibels | Bels | Nepers |
|---|---|---|
| 1 dB | 0.1 | 0.11512925 |
| 3 dB | 0.3 | 0.34538776 |
| 6 dB | 0.6 | 0.69077553 |
| 10 dB | 1 | 1.151292547 |
| 20 dB | 2 | 2.302585093 |
| 60 dB | 6 | 6.907755279 |
| 100 dB | 10 | 11.51292547 |
Worked examples: three directions
A level of 20 dB is 2 B or 2.302585093 Np. One neper is 8.685889638 dB, or 0.86858896 B. Two nepers make 17.37177928 dB. These look unusual, but they follow from the same base-e and base-10 relationship. Half a neper is 4.342944819 dB. Exact relationships make checks simple: 10 dB is exactly 1 B, and 1 dB is 0.11512925 Np. A 60 dB level is 6 B and 6.907755279 Np, and 100 dB is 10 B or 11.51292547 Np.
What a decibel difference means
Because the scale is logarithmic, +10 dB is ten times the power, +20 dB is ten times the amplitude, roughly +3 dB doubles power and +6 dB doubles amplitude. Two equal sources add about 3 dB, not twice the number. The converter does not do this arithmetic. It only relabels one level in another unit, so use it with levels, not with sums.
What it does not cover
Sound pressure in pascals, intensity in W/m², A-weighted levels and references like dBm are not handled. Without a reference, a decibel number says nothing about loudness by itself. For absolute levels, state the reference, such as 20 µPa for dB SPL in air. Frequency content, duration and distance from the source also change how a level is perceived, and none are modelled here. Hearing-safety limits, for instance, depend on both level and exposure time, so consult the relevant standard for those.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →