Decibels (dB)
The decibel is a logarithmic unit for ratios, one tenth of a bel.
Convert decibels to any level unit
1 decibel = 0.1 bels
Quick facts
- Unit
- Decibel (plural: decibels)
- Symbol
- dB
- Measures
- Sound Level / Decibels
- System
- Levels
- Equals
- 0.1 bels
- Definition
- One tenth of a bel: 10·log₁₀ of a power ratio.
1 decibel in other units
| Bels | 0.1 B |
| Power ratios | 1.258925412 P/P₀ |
| Amplitude ratios | 1.122018454 A/A₀ |
What is a decibel?
The decibel is a logarithmic unit for ratios, one tenth of a bel. It is used for sound levels, audio and radio signal strength, amplifier gain and attenuation. Every 10 dB is a factor of 10 in power.
Where the decibel sits among level units
The decibel is number 2 of 4 on our scale of level units, ordered from smallest to largest.
What decibels are used for
- Sound levels (dB SPL, dBA)
- Audio gain and volume
- Radio and Wi-Fi signal strength (dBm)
- Cable and fiber loss
Decibels in real life
- A quiet library is about 40 dB
- Normal conversation is about 60 dB
- A rock concert is about 110 dB
- Prolonged exposure above 85 dB can damage hearing
Top decibel conversions
Common amounts of decibels
- 0.1 dB
- 0.2 dB
- 0.3 dB
- 0.4 dB
- 0.5 dB
- 0.6 dB
- 0.7 dB
- 0.8 dB
- 0.9 dB
- 1 dB
- 1.5 dB
- 2 dB
- 2.5 dB
- 3 dB
- 3.5 dB
- 4 dB
- 4.5 dB
- 5 dB
- 6 dB
- 7 dB
- 7.5 dB
- 8 dB
- 9 dB
- 10 dB
- 11 dB
- 12 dB
- 13 dB
- 14 dB
- 15 dB
- 16 dB
- 17 dB
- 18 dB
- 19 dB
- 20 dB
- 21 dB
- 22 dB
- 23 dB
- 24 dB
- 25 dB
- 26 dB
- 27 dB
- 28 dB
- 29 dB
- 30 dB
- 31 dB
- 32 dB
- 33 dB
- 34 dB
- 35 dB
- 36 dB
- 37 dB
- 38 dB
- 39 dB
- 40 dB
- 41 dB
- 42 dB
- 43 dB
- 44 dB
- 45 dB
- 46 dB
- 47 dB
- 48 dB
- 49 dB
- 50 dB
- 51 dB
- 52 dB
- 53 dB
- 54 dB
- 55 dB
- 56 dB
- 57 dB
- 58 dB
- 59 dB
- 60 dB
- 61 dB
- 62 dB
- 63 dB
- 64 dB
- 65 dB
- 66 dB
- 67 dB
- 68 dB
- 69 dB
- 70 dB
- 71 dB
- 72 dB
- 73 dB
- 74 dB
- 75 dB
- 76 dB
- 77 dB
- 78 dB
- 79 dB
- 80 dB
- 81 dB
- 82 dB
- 83 dB
- 84 dB
- 85 dB
- 86 dB
- 87 dB
- 88 dB
- 89 dB
- 90 dB
- 91 dB
- 92 dB
- 93 dB
- 94 dB
- 95 dB
- 96 dB
- 97 dB
- 98 dB
- 99 dB
- 100 dB
- 110 dB
- 120 dB
- 130 dB
- 140 dB
- 150 dB
- 160 dB
- 170 dB
- 180 dB
- 190 dB
- 200 dB
- 210 dB
- 220 dB
- 230 dB
- 240 dB
- 250 dB
- 260 dB
- 270 dB
- 280 dB
- 290 dB
- 300 dB
- 310 dB
- 320 dB
- 330 dB
- 340 dB
- 350 dB
- 360 dB
- 370 dB
- 380 dB
- 390 dB
- 400 dB
- 410 dB
- 420 dB
- 430 dB
- 440 dB
- 450 dB
- 460 dB
- 470 dB
- 480 dB
- 490 dB
- 500 dB
- 600 dB
- 700 dB
- 800 dB
- 900 dB
- 1,000 dB
- 1,200 dB
- 1,500 dB
- 2,000 dB
- 2,500 dB
- 3,000 dB
- 4,000 dB
- 5,000 dB
- 10,000 dB
Convert decibels to all 5 other units
Levels
Ratios
Convert to decibels
Frequently asked questions
What is a decibel?
The decibel is a logarithmic unit for ratios, one tenth of a bel.
How is the decibel defined?
One tenth of a bel: 10·log₁₀ of a power ratio.
How many bels are in a decibel?
One decibel equals 0.1 bels.
How many power ratios are in a decibel?
One decibel equals 1.258925412 power ratios.
How many amplitude ratios are in a decibel?
One decibel equals 1.122018454 amplitude ratios.