Mastering for YouTube: loudness normalisation, uploads and why videos sound quiet

What YouTube does

YouTube measures integrated loudness and turns loud content down to about −14 LUFS. It does not turn quiet content up. That asymmetry is the whole story: a −9 LUFS master is reduced by about 5 dB, a −18 LUFS upload stays at −18 and sounds weak next to everything else.

'Stats for nerds' shows the reduction as a percentage: 'content loudness 5.1 dB, 56%' means the video is being played 5.1 dB below its own level.

Export settings that play at full level

• Master the audio to −14 LUFS integrated, −1 dBTP. YouTube leaves it untouched.
• Put the audio in the video at 48 kHz, 24-bit or 16-bit PCM, or AAC at 320 kbps if the editor forces a codec. Do not let the video editor normalise or 'auto-level' it.
• Check the finished MP4 with a LUFS meter before upload; some editors quietly add a −3 dB or −6 dB gain.

In our tests the difference between a raw Suno WAV (about −15 LUFS, −4 dBTP) and a −14 master on YouTube was small in level but obvious in tone: the master had the low end and the controlled highs, and the raw file did not.

Shorts and mobile

Shorts play on phone speakers with the same normalisation. Low frequencies below about 150 Hz do not come out of a phone speaker at all, so what carries a Short is the 200 Hz–4 kHz region. A master with weak low-mids, which is the typical AI-track profile, sounds hollow there. This is a mix-and-master tonal problem, not a loudness one.