Mastering for Spotify & Apple Music: LUFS, True Peak & File Specs

🎧 Mastering for the Algorithm: Your Guide to Streaming Loudness, Peaks, and File Best Practices

The loudness wars are over. In the age of digital streaming, mastering your music isn’t about simply making it as loud as possible—it’s about preparing it for the platform’s normalization algorithms to ensure your track sounds clear, punchy, and consistent across every listener’s device.

This technical breakdown will guide you through the essential parameters—LUFS targets, True Peak limits, and optimal file specs—to help you avoid the dreaded loudness penalty and preserve your music’s dynamic range on services like Spotify and Apple Music.

🎚️ The Loudness Standard: Integrated LUFS Targets

Loudness Units Full Scale (LUFS) is the international standard used by streaming services to measure the perceived average loudness of an entire track. Instead of only measuring the loudest moment (like a peak meter), LUFS considers the sound over time, factoring in how the human ear perceives different frequencies.

By using Loudness Normalization, platforms turn down tracks that are too loud and turn up tracks that are too quiet (within limits) to create a consistent listening experience.

• Spotify (-14 LUFS): If your track is louder than -14 LUFS, Spotify will turn it down. If it’s quieter, they will turn it up, but they will leave 1 dB of headroom to avoid distortion from their lossy encoding.

• Apple Music (-16 LUFS): This slightly lower target allows for more dynamic range. If your track is mastered louder, it will be turned down when a user has “Sound Check” enabled.

The Pro Tip: You do not have to hit these exact numbers. Many professional engineers still master for a dense, impactful sound, often in the -11 LUFS to -9 LUFS range. The key is to ensure your track sounds its best at this higher level, knowing the platform will turn it down without introducing any extra compression or limiting.

⚠️ Avoiding the Loudness Penalty and Compression Artifacts

The real danger is the Loudness Penalty, which occurs when your master is significantly louder than the platform’s target. When a track is turned down by the algorithm, its dynamic range is preserved. However, tracks that are too heavily compressed initially can sound flat and lifeless once they are normalized, giving you a perceived penalty in punch and clarity.

The Role of True Peak (TP)

While LUFS measures average loudness, True Peak (TP) measures the absolute maximum level of your audio, including inter-sample peaks—peaks that can occur between digital samples after a file is converted to a lossy format (like Spotify’s Ogg/Vorbis or Apple Music’s AAC).

• Rule of Thumb: Set the ceiling of your final limiter to -1.0 dBTP (decibels True Peak).

• Why? This small amount of headroom (-1 dBTP) is crucial. When the platform encodes your lossless file into a lossy streaming format, these inter-sample peaks can rise by up to $1\text{ dB}$, potentially causing clipping and distortion if your original master was at $0\text{ dBTP}$.

By maintaining a -1.0 dBTP ceiling, you ensure that the encoding process will not create unwanted clipping, which is a key source of nasty compression artifacts.

💿 Best File Type and Sample Rate for Delivery

When submitting your final master to your distributor, you want to send the highest quality, uncompressed file possible to give the streaming service’s encoder the best source material.

• File Format (Container): WAV or AIFF (lossless) are the industry standard and highly recommended. Spotify also accepts FLAC. Avoid lossy formats like MP3 for your master.

• Bit Depth: 24-bit is the modern standard for professional audio and should be your minimum. This provides ample resolution and dynamic range for the platform to work with. (32-bit float is also acceptable).

• Sample Rate: 44.1 kHz is the CD-quality standard and is perfectly fine. 48 kHz is also a common professional rate. If your entire production and mixing session was done at a higher rate (e.g., 96 kHz), it’s acceptable to submit a 24-bit/96 kHz file, as platforms like Apple Music support Hi-Res Lossless up to 24-bit/192 kHz.

Key Takeaway: Do not downsample or convert your sample rate just to hit a lower spec. If your session was 48 kHz/24-bit, export it as 48 kHz/24-bit WAV. The streaming services are best equipped to handle any necessary down-conversion.

✅ Your Mastering Checklist

1. Select Your Primary Target: Decide if you are prioritizing Spotify (-14 LUFS) or Apple Music (-16 LUFS), but aim for a master that sounds great when normalized to both.

2. Set Your Limiter Ceiling: Ensure your final master’s True Peak does not exceed -1.0 dBTP.

3. Find the Sweet Spot: Master your track for the desired impact and dynamic range. If you choose to go louder (e.g., -10 LUFS), accept that the platform will turn it down, but your creative vision will be preserved.

4. Export Correctly: Deliver your final track as a 24-bit WAV or AIFF at the original session’s sample rate (44.1 kHz or higher).

5. Verify: Use a dedicated LUFS meter and True Peak meter (like Youlean, Insight, or VisLM) to confirm your final file meets all the technical specifications before distribution.

Mastering for the algorithm is simply mastering with intelligence. By respecting the platform’s normalization, you ensure your music’s sonic quality, punch, and dynamic energy are heard exactly as you intended.