The LUFS Meter is a broadcast-standard loudness measurement tool. LUFS (Loudness Units relative to Full Scale) is the universally adopted metric for measuring perceived loudness of audio content.
Unlike traditional SPL or peak meters, LUFS uses K-frequency-weighting and mean-square measurement to approximate how humans perceive loudness across different frequencies. This makes it the standard required by broadcasters, streaming platforms, and regulatory bodies worldwide.
Use the LUFS Meter to:
The main display shows three loudness values updated in real time:
M (Momentary) — 400 ms sliding window. Shows instantaneous perceived loudness. Use this to spot brief peaks or dips.
S (Short-Term) — 3 second sliding window. Smooths out moment-to-moment variation. Useful for monitoring overall programme level.
I (Integrated) — Gated measurement over the full duration of your recording or broadcast. This is the number that streaming platforms and broadcasters use to judge compliance. Press Start to begin integration, Stop to pause, and Reset to clear.
LRA (Loudness Range) — The difference between the quietest and loudest Short-Term measurements (10th to 95th percentile). A high LRA indicates wide dynamic range; a low LRA indicates heavily compressed material.
TP (True Peak) — The maximum inter-sample peak level, measured via 4× oversampling. Values exceeding the target’s TP limit are flagged in red.
The horizontal bar meters beside M, S, and I provide a visual reference scaled from −60 to 0 LUFS. A green target marker shows the selected standard’s loudness target.
Plots Momentary (bright) and Short-Term (light) loudness over time. A green shaded band shows the target compliance window. Use this to identify sections of content that deviate from the target.
Select a target standard (EBU R128, ATSC A/85, Apple Podcasts, or Custom). Enable or disable True Peak measurement. Toggle automatic reset of integration when pressing Start.
When a stereo or multi-channel interface is connected, the LUFS Meter processes L and R channels independently through the K-weighting filter, then sums their mean-square power per ITU-R BS.1770-4 to produce M, S, and I readings. True Peak is tracked per channel (TP L / TP R). For mono sources (internal mic), a single channel is used and TP shows one value.
For multi-channel interfaces (>2 channels), use the Input Channels setting to select which physical channels map to L and R.
The Input Mode setting controls whether per-channel calibration trims are applied to the measurement:
LUFS is a relative measurement (dBFS-referenced), so microphone SPL calibration offsets are not applied. Only the Mux per-channel trims are relevant, and only in Mic mode.
The Analyze tab lets you import an audio file and run a complete EBU R128 loudness analysis offline. This is the same workflow used by professional tools for compliance checking before delivery.
Supported formats include WAV, AIFF, CAF, M4A, MP3, and any other format supported by Core Audio. Files at any sample rate are automatically resampled to 48 kHz for standards-compliant K-weighting.
How it works:
The PASS/FAIL verdict checks both loudness (within ±1.0 LU of target) and True Peak (below the target’s TP limit). Both must pass for an overall PASS.
The LUFS Meter implements the following international standards:
Defines the two-stage biquad filter (high-shelf pre-filter + high-pass at 38 Hz) used to approximate equal-loudness perception. All LUFS measurements are derived from K-weighted signal power.
Target: −23.0 LUFS ± 0.5 LU, True Peak limit −1.0 dBTP. Adopted by the European Broadcasting Union and mandated for broadcast across Europe. Defines the absolute gate at −70 LUFS and relative gate at −10 LU below ungated mean for Integrated loudness measurement.
Target: −24.0 LKFS, True Peak limit −2.0 dBTP. Required by the U.S. CALM Act for television broadcast. Uses the same measurement algorithm as EBU R128 with a 1 LU lower target.
Apple Podcasts recommends −16.0 LUFS with a True Peak limit of −1.0 dBTP. Spotify uses a similar normalization target. YouTube normalizes to approximately −14.0 LUFS. Setting the correct target ensures your content plays back at the intended level without platform-applied gain adjustment.
Uses 4× polyphase FIR oversampling to detect peaks that occur between digital samples. Standard peak meters miss these inter-sample peaks, which can cause distortion in downstream codecs (AAC, MP3, Opus). True Peak measurement prevents this.
LUFS measurements are relative to digital full-scale (dBFS) and do not require microphone SPL calibration. The active input device, channel configuration, and Mic/Line mode are shown in the header at the top of the meter display.
