True peak is the highest level of the reconstructed audio waveform, including the points between samples. Meters estimate it by oversampling, 4× in the ITU-R BS.1770 standard, and show it in dBTP. Sample peak, shown in dBFS, only reads the sample values. A master that peaks at 0 dBFS can have inter-sample peaks above 0 dBTP, which can clip in the playback converter or when the file is encoded to AAC, MP3 or Ogg. Spotify recommends masters peak no higher than −1 dBTP, and −2 dBTP for masters louder than −14 LUFS.
True peak vs sample peak
A digital file stores the waveform as a series of samples. When you play it, the converter turns those samples back into a continuous signal, drawing a smooth curve through them. The curve doesn't have to turn at a sample. When two neighbouring samples both sit near full scale, the curve between them can rise higher than either one.
A sample peak meter only looks at the stored values, so it misses that rise. A true peak meter oversamples the signal, working out extra points between the stored ones, and reports the highest of those. That is why the two readings differ, and why the true peak reading is equal to or higher than the sample peak.
dBTP vs dBFS
Both units use the same scale. 0 is digital full scale, and everything below it is a negative number. The difference is what gets measured.
| dBFS (sample peak) | dBTP (true peak) | |
|---|---|---|
| What it reads | The highest stored sample | The highest point of the reconstructed waveform |
| How | Reads the samples as they are | Oversamples, 4× in BS.1770 |
| Can it go above 0? | No, a sample can't exceed full scale | Yes, between samples |
| Use it for | Checking a file for digital overs | Setting a master's peak ceiling |
So a file can read −0.1 dBFS on a sample peak meter and +0.5 dBTP on a true peak meter at the same time. Both readings are correct. Only the second one tells you whether the playback chain will clip.
Why inter-sample peaks matter
Inter-sample peaks above 0 dBTP cause trouble in two places.
- The playback converter. If the reconstructed signal goes past full scale, a converter can clip it on the way out.
- Lossy encoding. Streaming services and many players encode to AAC, MP3 or Ogg. The encoder changes the waveform slightly, and a master already close to 0 dBTP can end up over it after encoding.
A ceiling of −1 dBTP leaves room for both. Spotify asks for more room, −2 dBTP, on masters louder than −14 LUFS.
Peaks and loudness normalization
True peak also decides how far Spotify can turn a quiet track up. On its default setting Spotify plays tracks at −14 LUFS. It turns loud tracks down, and it can turn quiet tracks up only as far as the peaks allow, keeping them under −1 dBTP.
Take a master at −16 LUFS with a true peak of −2 dBTP. To reach −14 LUFS Spotify would need to raise it 2 dB, which would put its peaks at 0 dBTP. It can raise it only 1 dB, so the track plays at −15 LUFS, 1 dB quieter than its neighbours. The same master with a true peak of −4 dBTP gets the full 2 dB. The loudness normalization guide explains how each service applies this.
True peak vs LUFS
They measure different things, and a master needs both readings. LUFS measures loudness over time, weighted to match how ears hear. True peak is the single highest point. Two masters that both peak at −1 dBTP can sit at −16 LUFS and −8 LUFS, depending on how much they were compressed and limited.
Streaming services set playback level from integrated LUFS. True peak tells you whether the file will clip and how much room Spotify has to turn it up. For the loudness side, see what LUFS measures and how loud to make your master.
Using a true peak limiter
A limiter that only watches samples holds the sample peak to its ceiling. Set it to −1 dB and the file reads −1 dBFS, but the true peak can still read higher. A limiter with a true peak mode estimates the peaks between samples, the way a true peak meter does, and holds those to the ceiling instead.
- Put the true peak limiter last in the master chain, after any clipper or saturation.
- Set the ceiling to −1 dBTP, or −2 dBTP if the master will be louder than −14 LUFS.
- Export at the final sample rate and bit depth, then measure the exported file with a true peak meter. Sample rate conversion and dither after the limiter can change the peaks.
- If the exported file reads above your ceiling, lower the ceiling a little and export again.
If the limiter has no true peak mode, set its ceiling lower than your target and check the export on a true peak meter until it reads where you want.
How to check true peak
If your DAW's master meter has a true peak mode, switch it on when you master. Check the exported file, not only the live meter on the master bus.
ABSeq measures true peak on every loaded track with 4× oversampling and shows it in dBTP beside the integrated LUFS. The reading turns red above −1 dBTP, so a file over Spotify's recommended ceiling stands out when you load your exports side by side. The track readouts section of the help guide explains each value.
Questions
What is the difference between true peak and sample peak?
Sample peak is the highest stored sample, in dBFS. True peak is the highest point of the waveform once it is reconstructed between the samples, estimated by oversampling and shown in dBTP. True peak is equal to or higher than sample peak, and it can go above 0 even when no sample does.
What true peak should I use for mastering?
−1 dBTP or lower, which is what Spotify recommends. For masters louder than −14 LUFS, Spotify asks for −2 dBTP. The headroom protects against inter-sample peaks clipping in the converter or when the file is encoded to AAC, MP3 or Ogg.
What does −1 dBTP mean?
It means the highest point of the reconstructed waveform, including peaks between samples, sits 1 dB below digital full scale. That 1 dB leaves room for the converter and for lossy encoding, so the master doesn't clip on playback.
Why does my true peak read higher than my limiter ceiling?
Your limiter is probably holding the sample peak, not the true peak, so peaks between samples still go over. Switch on its true peak mode if it has one, or lower the ceiling, and measure the exported file on a true peak meter.
What true peak does YouTube want?
YouTube turns loud tracks down to about −14 LUFS and doesn't publish full loudness rules. Spotify does, and its −1 dBTP ceiling, or −2 dBTP above −14 LUFS, works for the same master on YouTube.