| Sones | Approx. dB SPL (at 1 kHz) | Perceived Loudness | |-------|----------------------------|--------------------| | 0.5 | ~35 dB | Very quiet | | 1.0 | 40 dB | Reference | | 2.0 | ~50 dB | Twice as loud as 1 sone | | 4.0 | ~60 dB | Twice as loud as 2 sones | | 8.0 | ~70 dB | Twice as loud as 4 sones | | 16.0 | ~80 dB | Very loud (vacuum cleaner) |

And if you need to convert one to the other — remember it’s an at best. Your ears are the ultimate judge. Want a quick reference? For most common household fans and vents: 1 sone ≈ 40 dB, 2 sones ≈ 50 dB, 4 sones ≈ 60 dB, but expect variation of ±5 dB depending on pitch.

One sone is defined as the loudness of a 1 kHz tone at 40 dB SPL (sound pressure level).

A sound judged to be twice as loud is 2 sones. A sound half as loud is 0.5 sones. This makes sones intuitive for product design and consumer comparisons.

If you want to know how loud something seems to a person, use sones. If you want to know the physical sound pressure (for engineering or hearing safety), use dB.

If you’ve ever shopped for a range hood, a bathroom exhaust fan, or a leaf blower, you’ve likely seen two different units for noise: sones and decibels (dB) . At first glance, both seem to measure "how loud" something is. But they are not the same, and you cannot simply convert between them with a single formula.