How to Normalise Volume Across Tracks So Songs Play at One Level
The fix is loudness normalisation: software measures how loud each track actually sounds, then either stores a per-song volume correction in the file's tags (ReplayGain) or adjusts the audio itself so every song plays at the same level. The tag method is the one to try first, because it never touches the music.
Uneven volume is not your imagination or a bad download. Songs are mastered at very different loudness levels depending on their era and genre, and your library mixes all of them. This guide explains why the gaps exist, how to scan and tag your files, when a permanent change is the better tool, and which players honour the tags.
Why are some tracks so much louder than others?
Loudness is decided at mastering, the last production step before a song is released. Over the 1990s and 2000s, labels pushed masters louder and louder with heavy compression so songs would stand out on the radio — the so-called loudness war. A pop single from that era sounds noticeably more forceful than a jazz record from decades earlier, even at the same volume knob position.
Your library probably mixes all of these: old rips, new releases, live recordings, tracks from different free sources. The trap is that a file's peak level lies. A quiet-sounding ballad can still hit the maximum digital peak on one drum hit. Loudness is about the average energy of the whole song, not the tallest peak — which is why a 'maximise volume' button that only looks at peaks never actually evens things out.
What is ReplayGain, and how does it fix the problem?
ReplayGain is a loudness standard built for exactly this. A scanner analyses each file, models how loud human hearing perceives it, and calculates how many decibels the player should add or subtract to bring it to a shared reference level (89 dB in the spec). That number is written into the file's metadata as a tag, for example REPLAYGAIN_TRACK_GAIN. The audio itself is not touched.
The scanner computes two values. Track gain makes every song equally loud — what you want for shuffle and mixed playlists. Album gain moves a whole album by one shared amount, so the quiet intro and the loud finale keep their intended contrast. A compatible player reads the tag at playback and adjusts the volume for you automatically.
Should you use tags or change the audio itself?
You have three routes, and they are not equal. ReplayGain tags are the cleanest: lossless and reversible, but they only work in players that read them. MP3Gain rewrites the gain fields inside MP3 frames, so the file itself plays louder or quieter in every app — still without decoding and re-encoding the audio, and still reversible. A full re-encode with a loudness filter, such as ffmpeg's loudnorm, works on any format and any player, but re-encoding an MP3 to MP3 costs a generation of quality you cannot get back.
| Method | Changes the audio? | Reversible? | Works in any player? |
|---|---|---|---|
| ReplayGain tags | No — metadata only | Yes, delete the tags | Only if the player reads the tags |
| MP3Gain gain change | Gain values only, no re-encode | Yes, with its undo | Yes |
| Re-encode (loudness filter) | Yes, new lossy file | No — keep a backup | Yes |
MP3Gain is MP3-only and adjusts in steps of 1.5 dB; for FLAC or Opus libraries, use tags or a re-encode.
How do you scan your library and write ReplayGain tags?
The scan is best done on a computer, because tagging a large library on a phone is slow. foobar2000 (free, Windows) does it in a few clicks. MusicBee has the same feature: select the tracks, right-click and pick Analyze Volume. One thing to know before you start: scan again after you edit a file. Trimming a song with the MP3 cutter changes its measured loudness, so the old tag no longer matches.
- Install foobar2000 and drag your music folder into its playlist window.
- Select everything with Ctrl+A.
- Right-click the selection, choose ReplayGain, then 'Scan selection as albums (by tags)'. This groups songs by their album tag so album gain is calculated correctly. If your files are a mixed bag with no album tags, choose 'Scan per-file track gain' instead.
- Wait for the scan, then confirm when it asks to save the results. It writes track and album gain values into the files' tags.
- Copy the files back to your phone if they were not already there, then enable ReplayGain in your player — the next section shows where.
Scanning only writes metadata; your audio is not re-encoded or altered in any way.
How do you make the volume change permanent?
Pick the permanent route when your playback device ignores tags — many car stereos, cheap MP3 players and some stock phone apps do. For MP3 files, MP3Gain is the safer tool because it never re-encodes.
For other formats, re-encode with a loudness filter. On a computer with ffmpeg installed, ffmpeg -i input.flac -af loudnorm=I=-16:TP=-1.5 -b:a 192k output.mp3 converts the file and normalises loudness in one pass. The I value sets the target loudness; -16 LUFS is a common choice for music libraries. Keep the original file — the output cannot be converted back to the original quality.
- Open MP3Gain and use Add File or Add Folder to load your tracks.
- Leave the target volume at the default 89 dB unless the whole library sounds too quiet afterwards — raising the target increases the risk of clipping.
- Click Track Analysis, or Album Analysis for a full album, to measure each file.
- Check the clipping column. If a track would clip, lower the target by a decibel or two rather than accepting distortion.
- Click Track Gain, or Album Gain, to apply. The change is written into the file, works in every player, and MP3Gain keeps what it needs to undo it later.
Re-encoding an MP3 to another MP3 just for loudness is lossy; prefer MP3Gain or tags when the file is already an MP3.
Which music players actually read ReplayGain tags?
Tag-based normalisation only works where the player cooperates. Support is strong in enthusiast apps and patchy in stock ones.
If your everyday player sits in the 'ignores it' camp, don't fight the app — use the permanent method from the previous section instead.
- foobar2000 (Windows, Android, iOS): full ReplayGain support; on mobile, enable it in the playback settings.
- Poweramp (Android): turn it on under Settings, Audio, Replay Gain.
- VLC (desktop): Tools, Preferences, Audio, then set 'Replay gain mode' to Track or Album.
- Windows Media Player and many pre-installed phone players: ignore the tags entirely.
- Apple's apps use their own Sound Check values, not standard ReplayGain tags.
Does normalisation matter if you mostly stream?
You don't need to manage this for streaming. Spotify, YouTube and similar services measure loudness on their side and turn loud tracks down to match the rest — your file tags never reach their players. One practical effect: heavily loudness-squashed masters gain nothing there, because the service simply turns them down.
Normalisation pays off for files you own: rips of your CDs, public-domain and Creative Commons downloads, free tracks artists give away, your own recordings. Scan whatever you add to the library — including MP3s you make with the search and convert tool — and shuffle stops jumping between loud and quiet.
Frequently asked questions
Does ReplayGain reduce audio quality?
No. Tag-based ReplayGain only writes text metadata, so the audio stream is untouched and deleting the tags restores the original exactly. MP3Gain's gain change also avoids re-encoding and is reversible. Only a full re-encode with a loudness filter produces a new lossy file, so keep your originals if you go that route.
Can I normalise volume on my phone without a computer?
Partly. If your files already carry ReplayGain tags, an Android player that reads them gives you even volume with no computer involved. Writing the tags in the first place is far easier on a computer, though — scan the library there, then copy the files to your phone.
What is the difference between peak normalisation and loudness normalisation?
Peak normalisation raises a file until its loudest single sample hits full scale. It ignores how loud the track actually sounds, so a compressed pop single and a quiet ballad still end up miles apart. Loudness normalisation measures the average perceived level and matches that, which is what you want for a mixed library.
Does normalising squash the quiet and loud parts of a song together?
No — that is compression or limiting, a different process. Normalisation shifts the whole track up or down by one fixed amount, so the dynamics the artist intended stay intact. Album gain goes further and preserves the deliberate loud and quiet differences between songs on the same album.
Does ReplayGain work on FLAC, AAC or Opus files?
Yes. ReplayGain is a tag standard, not an MP3 feature, and scanners like foobar2000 write it for most common formats. The format-specific tool is MP3Gain, which only works on MP3 because it edits the gain fields inside MP3 frames. For other formats, use tags or a re-encode.