Decibel Calculator
Combine sound levels in dB.
A + B combined
63.0 dB
+3 dB on top of A (equal sources)
2 × Source A
63.0 dB
Common dB levels
- 0 dB: Threshold of hearing
- 30 dB: Whisper
- 40 dB: Quiet library
- 60 dB: Normal conversation
- 70 dB: Vacuum cleaner
- 80 dB: Heavy traffic
- 90 dB: Lawnmower
- 110 dB: Rock concert
- 120 dB: Threshold of pain
- 140 dB: Jet engine at 30m
Decibels are logarithmic. Doubling sound power adds 3 dB. Doubling sound pressure (perceived loudness) adds 6 dB. NIOSH limits 8-hour exposure to 85 dB - every 3 dB above doubles the damage.
About
Add two sound sources or N identical sources. Decibels are logarithmic - two equal sources sum to +3 dB, ten identical to +10 dB. Useful for audio, acoustics, and noise exposure planning.
How to use
- Enter two sound levels in dB.
- Read the combined level.
FAQ
Why does adding two equal sources only add 3 dB?+
dB is a log scale. Doubling sound power = +3 dB. Doubling perceived loudness needs 10× the power = +10 dB.