# What is LUFS?

LUFS (Loudness Units Full Scale) measures how loud something actually sounds to a person, averaged over time — unlike peak level, which only measures the single loudest instant. Podcast platforms use it as their delivery target: Apple Podcasts wants −16 LUFS, Spotify and YouTube −14 LUFS.

![Three episodes in one feed at different loudness. The quiet one makes the listener reach for the volume; the loud one gets turned down by the platform. Hitting the target means yours arrives sounding the way you mixed it.](https://mubert.com/tools/cast/docs-media/diagrams/what-is-lufs.svg)

The reason it exists: a quiet recording with one loud door slam has a high peak but is still a quiet recording. LUFS matches how loudness is perceived, so it is the number platforms can meaningfully normalize against.

A lower number is quieter — and because these are negative, −23 LUFS is quieter than −14 LUFS.

In Cast you never type this number. Pick your platform on export and the target is applied.

## Related

- [What LUFS should my podcast be?](https://mubert.com/tools/cast/docs/loudness-lufs)
- [What is true peak, and why −1 dB?](https://mubert.com/tools/cast/docs/what-is-true-peak)
- [What does normalizing audio mean?](https://mubert.com/tools/cast/docs/what-is-normalization)

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Source: https://mubert.com/tools/cast/docs/what-is-lufs · Cast docs
Last updated: 2026-09-14