Loudness violations are silent rejects: the cut plays fine, the client approves, and the broadcaster or platform bounces it back for being 2 LU hot. The numbers are standardized and short - a US broadcast mix at −24 LKFS ±2 (ATSC A/85), European broadcast at −23 LUFS ±0.5 (EBU R 128), Netflix at −27 LKFS ±2, each with a true-peak ceiling - and the measurement pass belongs in your QC before sign-off, not after delivery. Here is the table, the measurement method, and where it sits in the review loop.
Why the specs exist
Before normalization, commercials were mixed louder than programs - viewers rode the volume remote and broadcasters got complaints. The US CALM Act (2010) requires commercials to match the loudness of adjacent programming, with the FCC recognizing ATSC A/85 as the recommended practice (the FCC's CALM Act page). Europe standardized the equivalent with EBU R 128. Same physics, slightly different targets per region.
The spec table
| Target | Program loudness | Measurement basis | True-peak max |
|---|---|---|---|
| ATSC A/85 (US broadcast) | −24 LKFS ±2 LU | Dialogue-gated (anchor-based) | −2 dBTP |
| EBU R 128 (European broadcast) | −23 LUFS ±0.5 LU | Program loudness (relative gating) | −1 dBTP |
| Netflix (originals delivery, their partner-help spec) | −27 LKFS −2/+2 LU | Dialogue-gated | −2 dBTP |
LKFS and LUFS are the same scale under two names - ITU-R BS.1770 loudness units; broadcast bodies just picked different letters. The measurement-basis column matters more than the acronym: A/85 and Netflix anchor on dialogue, so a dialogue-gated meter is not optional for those targets, and R 128's tolerance is the tightest of the three at ±0.5 LU.
Streaming is a different animal
Streaming platforms normalize playback loudness on their side - YouTube turns loud content down and does not boost quiet content, with community measurements converging around −14 LUFS as the playback target. YouTube publishes no official loudness number; the official touchpoints are the Content Loudness meter in YouTube Studio (flagging content it considers too loud) and Stats for Nerds during playback. Practical read: mix social cuts sensibly in the −14-ish neighborhood, but do not treat any streaming number as a compliance spec the way A/85 is for broadcast.
How to measure
- Use a loudness meter, not your ears. Every NLE ships one (Premiere's Audio Track Mixer loudness radar, Resolve's built-in loudness meters); standalone meters work too. A waveform peak meter tells you nothing about perceived loudness.
- Measure the whole program, gated. For A/85 and Netflix targets, dialogue-gated measurement is required - a music-heavy intro must not drag the reading.
- Check true peak, not just loudness. Sample peaks can pass while inter-sample peaks clip on playback; a true-peak limiter at −2 dBTP (broadcast US/Netflix) or −1 dBTP (R 128) is the finishing step.
- Measure the final export. Loudness changes when tracks get muted, ducked, or re-rendered - the number that counts is on the delivered file.
Where this sits in the review loop
The division of labor is simple: the meter proves the spec; the review link proves the decision. Run the loudness pass before the client sees the cut, so an approval never lands on a mix that will bounce at QC - the mix-review layer itself (what to listen for in a round) is in the audio review workflow, and the loudness gate appears again in the TV-commercial approval chain, where clearance and traffic gates assume the CALM Act number. Delivery context: the delivery checklist.
FAQ
Are LKFS and LUFS the same thing?
Yes - both name the ITU-R BS.1770 loudness unit. ATSC documents use LKFS; EBU documents use LUFS. The number transfers directly; only the label and the surrounding spec change.
What happens if my mix is too loud?
For broadcast, rejection at QC and a re-delivery - that is the operational point of A/85 and R 128. For streaming, the platform usually just turns playback down, which flattens your mix decisions instead of bouncing the file.
What should social media cuts target?
No official spec exists; community-measured platform normalization sits around −14 LUFS, and mixing in that neighborhood means the platform will not need to turn your content down. Treat it as practice, not compliance.
Do I need a calibrated monitoring environment?
For the loudness number, no - the meter is objective and travels with your project. Calibration matters for judging tone and mix balance, which is a different question from the delivery spec.
Why is Netflix's target quieter than broadcast?
Different gating and different reference level choices by each spec's authors - Netflix mixes dialogue-anchored at −27 LKFS for a consistent streaming experience, while broadcast regions standardized −24 (US) and −23 (Europe). Always apply the target of the delivery destination, not a universal number.