Glossary
What is LUFS?
By the KeyMo team · Updated
LUFS stands for Loudness Units relative to Full Scale. It measures how loud audio sounds over a whole programme, not how high its loudest peak reaches. A lower number is quieter, so -23 LUFS is quieter than -14 LUFS. LKFS is the same unit under another name.
LUFS meaning: loudness, not peaks
ITU-R BS.1770 introduced the Loudness Unit (LU) and LUFS, Loudness Units referenced to Full Scale. The EBU, Europe's broadcasting union, states that LUFS is equivalent to LKFS, the name used in the ITU text. The EBU says it uses LUFS.
The reason the measure exists is practical. The EBU says that normalising by peak level led to large loudness differences between programmes and channels, and that these differences cause most viewer and listener complaints. A loudness unit measures what the ear reports. A peak meter measures only the tallest spike.
A loudness meter that follows ITU-R BS.1770 and EBU Tech 3341 measures the signal in its entirety, without emphasis on speech, music or effects.
Published LUFS targets and what each applies to
| Source | Number | Applies to |
|---|---|---|
| EBU R 128 | -23.0 LUFS programme loudness, true peak not above -1 dBTP | Broadcast, not streaming platforms |
| EBU R 128 s1 | -23.0 LUFS, maximum short-term -18.0 LUFS, true peak -1 dBTP | Short-form content such as adverts and promos |
| Spotify | -14 dB LUFS (listener settings: Loud -11, Normal -14, Quiet -19) | Music tracks on an audio service |
| Apple Podcasts | About -16 dB LKFS, +/- 1 dB, true peak not above -1 dB FS | Podcast audio in RSS feeds |
The numbers disagree because the media do. None of them is a rule from YouTube, TikTok or Instagram. The help pages we read for those platforms give no loudness number, so do not treat any figure above as theirs.
What it means for podcast clips
A clip is heard in a feed, one after another with other videos. If your clip is much quieter or louder than the neighbours, viewers adjust their volume, and a sudden loud music bed is a good reason for them to swipe away. Two choices follow.
- Match the number to the place the audio will be judged. A podcast feed has Apple's figure, a broadcast has the EBU's, and a social clip has no official figure, so pick a consistent in-house level for all your clips.
- Measure the finished clip, not the source episode. Adding music changes the integrated loudness.
- Keep true peaks below -1 dB, which both EBU and Apple give as a ceiling.
Common mistakes
- Mixing up peak level and loudness. A clip can peak at the same level as another and sound several LU louder.
- Reading one short moment instead of the whole clip. Integrated loudness covers the entire programme, and short-term loudness covers a moving window.
- Pushing the level up until the true peak clips because a number says so.
- Setting music louder than the voice. Voice-led clips need the music to step back; see audio ducking.
Where KeyMo touches it
KeyMo has a music library with moods, and the guide on background music for podcast clips covers how to choose. This page does not claim that KeyMo measures or normalises clips to a LUFS target, so run a loudness meter on the exported file if a level matters to you.
Sources: EBU R 128: Loudness normalisation and permitted maximum level of audio signals (checked 11 October 2026); EBU R 128 s1: Loudness parameters for short-form content (checked 11 October 2026); ITU-R BS.1770: Algorithms to measure audio programme loudness and true-peak audio level (checked 11 October 2026); Loudness normalization (Spotify for Artists) (checked 11 October 2026); Audio requirements (Apple Podcasts for Creators) (checked 11 October 2026).