Learn — By WATMM Desk —
What is true peak (dBTP)?
True peak is the highest level a digital audio waveform reaches once it is rebuilt as a continuous signal, including peaks that fall between samples. It is measured with the ITU-R BS.1770 method and shown in dBTP; Spotify asks for masters at or below -1 dBTP.
Key facts
- ITU-R BS.1770 defines true-peak level as the maximum value of the signal waveform in the continuous time domain, which may be higher than the largest sample value.
- The BS.1770 method oversamples 4x (48 kHz to 192 kHz), filters, and reports the result in dB TP, decibels relative to full scale.
- Spotify recommends keeping masters below -1 dB true peak, and below -2 dB for masters louder than -14 LUFS integrated.
True peak is the highest level a digital audio signal reaches when it is rebuilt as a continuous waveform, including peaks that land between the stored samples. It is written in dBTP (or "dB TP"): decibels relative to digital full scale, measured as a true peak.
The definition
The standard is ITU-R BS.1770, whose current version, BS.1770-5, dates from November 2023. Its Annex 2 defines true-peak level as "the maximum (positive or negative) value of the signal waveform in the continuous time domain", and notes this "may be higher than the largest sample value".
Why sample peaks under-read
An ordinary peak meter reads the largest sample. The recommendation says such meters "do not always register the true-peak value", and that for real-world transients with lots of high-frequency content the under-read "can commonly be several dBs". These hidden overs are often called intersample peaks.
How it is measured
BS.1770 Annex 2 sets out the steps, assuming a 48 kHz signal:
- Attenuate by 12.04 dB for headroom (not needed in floating point).
- Oversample 4x, from 48 kHz to 192 kHz, with a low-pass interpolation filter.
- Take the absolute value.
- Convert to dB and add the 12.04 dB back. The result is in dB TP.
The same recommendation also defines the loudness measurement behind LUFS.
Where the number matters
Spotify's loudness guidance says to keep masters "below -1dB TP (True Peak) max", so no extra distortion is introduced when it transcodes to lossy formats (Ogg/Vorbis and AAC). For masters louder than -14 LUFS integrated, it advises keeping true peak below -2 dB.
What we think
A 0.0 dBFS sample-peak ceiling is a habit worth dropping. Set your limiter to true-peak mode and leave at least 1 dB, more if the master is loud, because the cost is a fraction of a decibel of loudness that normalisation takes away anyway. The bigger point: a true-peak meter is only an estimate (BS.1770 itself calls it one), so treat -1 dBTP as a floor for headroom, not a target to hit exactly. For the limiter side, see limiting and true peak explained.
Sources
- Recommendation ITU-R BS.1770-5: Algorithms to measure audio programme loudness and true-peak audio level, ITU (primary source). Accessed 26 Oct 2026.
- BS.1770: Algorithms to measure audio programme loudness and true-peak audio level, ITU (primary source). Accessed 26 Oct 2026.
- Loudness normalization, Spotify (primary source). Accessed 26 Oct 2026.
Researched with AI assistance, written and checked by WATMM Desk.