Mixing and Mastering for Spotify and Apple Music: What Artists Need to Know

Most listeners now hear new music on a streaming service. That changes how mixes and masters are judged, because services do not simply play your file as delivered. They analyze loudness and adjust playback so that tracks from different artists sit at a similar level.

Plenty of misinformation circulates about this. Some artists believe every song must be mastered to exactly -14 LUFS. Others assume loudness no longer matters. Neither is true. This guide explains what the platforms document, what they leave to you and how a mixing and mastering engineer approaches a release meant for streaming.

Mixing versus mastering

The two stages have different jobs, and confusing them leads to wasted money and disappointing results.

Mixing balances the individual tracks of a song: drums, bass, guitars, vocals and effects. The mixing engineer sets levels, panning, tone and dynamics so that each part has space and the song has impact.

Mastering works on the finished stereo mix. The mastering engineer evaluates tone, dynamics, stereo image and level, makes subtle corrections and prepares the file for distribution. For an album, mastering also makes the songs work together, with consistent tone and level and well-judged gaps between tracks.

A master cannot fix a problem baked into a mix, such as a buried vocal or a boomy kick, without side effects. Equally, a good mix benefits from mastering because a second set of ears, in a different room, catches issues the mixer no longer hears. At Yave Rust, mastering on released projects has included collaborations with Jack Control and Maor Applebaum at Enormous Door Mastering, and roles differ by release as the site notes.

What loudness normalization does

Loudness normalization is a playback feature. The service measures the integrated loudness of a track, which is its average perceived loudness over the full length, and turns the playback level up or down toward a reference level. The goal is that listeners do not need to adjust the volume between songs.

Spotify explains its approach in its loudness normalization article for artists. Normalization happens during playback, so your uploaded file is not altered. The default reference is -14 dB LUFS, and listeners on Spotify's paid tier can also choose a Loud mode at about -11 LUFS or a Quiet mode at -19 LUFS. Spotify notes that the web player and some third-party devices do not apply normalization, so some people hear your master as delivered and others hear it adjusted.

Apple Music works differently in detail. Apple's Apple Digital Masters page describes how its encoder can use the high-resolution masters that engineers create, and says Apple Music now offers lossless versions. Apple documents its volume-leveling options separately in its support pages. The details of each service can change, so check the current pages before you finalize a release.

What LUFS means

LUFS stands for Loudness Units relative to Full Scale. It measures perceived loudness rather than the highest signal peak, and it accounts for how human hearing responds to different frequencies. iZotope's guide to LUFS explains the main readings: momentary, short-term and integrated loudness, loudness range and true peak. It also stresses that the numbers are a reference and not a substitute for listening.

A useful way to think about it: peak level tells you how high the highest wave goes, while LUFS tells you how loud the track feels on average.

What true peak means

True peak measures the highest level of the signal after it is reconstructed as an analog waveform, which can exceed the highest sample value. When a master is converted to a lossy format such as those used for streaming, those inter-sample peaks can distort. This is why mastering engineers leave a little headroom below digital full scale rather than pushing peaks to the maximum.

Is -14 LUFS a target you must hit?

No. Spotify's reference level describes how it normalizes playback. It is not a rule that masters must be exactly that loud, and no platform rejects a track for being louder or quieter.

Here is what happens in practice. If a master is louder than the reference, the service turns it down. If a master is quieter, some services turn it up when headroom allows, while others do not. In both cases, a heavily limited master does not play louder than a dynamic one after normalization. It may simply sound more compressed.

For this reason, many engineers no longer chase maximum loudness. They set the level that serves the music, then check the master against streaming conditions. A punk record may be mastered louder and denser than a jazz trio recording, and both can be right for their genre.

Practical guidelines for a streaming-ready master

These are points mastering engineers commonly consider. Treat them as principles, not fixed rules.

Leave headroom for conversion. Spotify recommends keeping true peak at or below -1 dB TP for its lossy formats, and below -2 dB TP if your master is louder than -14 LUFS integrated, because louder tracks are more prone to distortion when encoded. Spotify also says you only need to deliver one high-quality stereo master per track.

Preserve dynamics where the music needs them. Dynamics give a song contrast between verse and chorus. Over-limiting flattens that and can make a master feel tiring.

Judge by ear and by meter. Meters help verify, but the final decision is musical. Compare your master against reference tracks at matched loudness, so you evaluate tone and punch rather than volume.

Check on multiple systems. Listen on monitors, headphones, earbuds, a phone speaker and a car if possible. Streaming listeners use all of them.

Keep the original high-resolution file. Deliver and archive a master at the highest quality, typically 24-bit WAV, and let platforms and distributors create their own encoded versions.

Preparing your mix for mastering

Whether the mix and the master come from the same engineer or two different ones, you can improve the result by delivering a clean mix.

• Do not leave a limiter or heavy bus compressor on the master channel unless the mixing engineer intends it to be part of the sound. Ask for a version with and without if unsure.
• Leave headroom. Peaks well below digital full scale give the mastering engineer room to work.
• Deliver the mix at the original sample rate and in 24-bit or higher, without dithering.
• Include notes about anything unusual, such as intentional distortion or a deliberately quiet intro.
• Label the files clearly and provide a version for reference if there are alternates, such as an instrumental.

Singles, EPs and albums

For a single, mastering focuses on one song's tone and level. For an EP or album, the engineer also compares songs against one another, ensuring one track does not jump out as louder or darker than the next. Sequence and spacing between songs are adjusted for flow. Discuss the running order early and send the final order with your files.

Streaming platforms generally apply normalization to the track level by default, but some listening modes, such as album mode in certain apps, preserve the relative levels within an album. Ask your mastering engineer how they handle this when mastering a full-length release.

A quick pre-release checklist

Before you approve the master, run through this short list:

1. Listen to the full track on at least three different systems.
2. Compare against a reference song with the playback volume matched.
3. Confirm the start and end of each file: no clicks, clean fades, correct silence.
4. Check the file name, format and sample rate against your distributor's requirements.
5. Archive the final mix, the master and the session notes together.

Metadata and distribution

Your master is only part of a release. Distributors handle delivery to streaming services and ask for metadata such as titles, credits and identifiers. Your distributor provides its own requirements, and it is wise to confirm file format and artwork rules before the final bounce. Mixing and mastering engineers can supply technical details, but not the legal and administrative side of the release.

Remote workflow

You do not need to be in the studio to get a mix and master. Files can be exchanged online, and feedback can be given on streaming links or audio files. The online mixing and mastering article explains the process step by step. If you are deciding between analog hardware and software for the mix, the article on analog vs. digital mixing breaks down the differences.

Frequently asked questions

References

• Loudness normalization — Spotify Support
• Apple Digital Masters — Apple
• What are LUFS? The complete guide — Ian Stewart, iZotope