Measures: Sound level — how loud, on a power ruler
Decibel
Loudness on a power-of-ten ruler.
Sound levelHow it's defined
Not a size but a ratio: +10 dB means ten times the power, +20 dB means a hundred times. Sound level in dB always hides a reference (for air, 20 micropascals — about the quietest audible sound). Logarithmic, like pH — which is why 90 dB is not "50% louder" than 60 dB but a thousand times the power.
Convert — honestly
The decibel can't go in a simple converter, and pretending otherwise would be a lie: it's a logarithmic ratio, not a size. +10 dB always means ten times the power, and a sound level in dB only becomes a real quantity once you know the reference it's measured against (for sound in air: 20 micropascals). That's the honest answer — and it's the same reason pH can't be "converted" to anything.
Where you meet it
- Soundii-to-be — its entire subject
- Headphone safety warnings (85 dB, 8 hours)
Other ways to measure sound level
On this map, it stands alone for its quantity.
Source
This page is an authored summary of the authoritative definition — checkable one click away.
NIST Special Publication 811 — Guide for the Use of the SI