How fan noise adds up
Sound levels combine on a log scale. For identical fans, the total is one fan's rating plus 10 x log(number of fans), as fan maker Oriental Motor explains. For mixed fans, the calculator converts each rating to sound energy, adds them, and converts back.
- Doubling identical fans adds about 3 dB.
- Ten identical fans add 10 dB over one.
- One loud fan drowns out several quiet ones, so swap the loudest fan first.
Why your PC may sound different
Fan ratings are taken at full speed, and each brand measures its own way. Your fans rarely run flat out, and the case, the distance to your ears and the room all change what you hear. Treat the result as a way to compare setups, not as a meter reading.
The fastest way to cut noise is a gentler fan curve. Our sister site has a fan curve tool that sets one up from your temperatures.
Where the preset numbers come from
Each preset is the maker's own maximum rating: Noctua, Phanteks and Lian Li. Reverse blade versions are often a little louder, which you can see with the Phanteks and Lian Li pairs. Our dual chamber guide explains when reverse fans are worth it.