LUFS / Loudness Units relative to Full Scale / LKFS

loudness loudness normalization true peak

Loudness Units relative to Full Scale – the standardized measurement unit for perceived audio loudness according to ITU-R BS.1770, used worldwide for broadcast compliance, streaming platform specifications, and professional audio production to ensure consistent listening experiences.

What is LUFS?

LUFS (Loudness Units relative to Full Scale) is the standardized unit for measuring perceived audio loudness according to ITU-R BS.1770. LUFS is identical to LKFS and forms the basis for all modern loudness standards.

Basic Principle

Aspect	Description
Definition	Perceived Loudness
Standard	ITU-R BS.1770
Equivalent	LKFS (identical)
Reference	0 dBFS = 0 LUFS

LUFS vs. LKFS

Aspect	LUFS	LKFS
Meaning	Loudness Units FS	Loudness K-weighted FS
Standard	EBU	ITU/ATSC
Value	Identical	Identical
Region	Europe preferred	USA preferred

Measurement Process

Component	Description
K-Weighting	Frequency Curve
Channel Weighting	Surround Adjustment
Gating	Exclude Silence
Integration	Temporal Averaging

K-Weighting Curve

Frequency	Adjustment
< 100 Hz	Reduced
100-2000 Hz	~Neutral
2-4 kHz	+4 dB Shelf
> 4 kHz	+4 dB (boosted)

Measurement Types

Type	Time Window	Application
Momentary	400 ms	Real-time Monitoring
Short-term	3 seconds	Short Passages
Integrated	Full Program	Compliance

Target Values by Platform

Platform	LUFS	True Peak
Netflix	-27 (±2)	-2 dBTP
Amazon	-24	-2 dBTP
Spotify	-14	-1 dBTP
YouTube	-14	-1 dBTP
Apple Music	-16	-1 dBTP
Broadcast EU	-23 (±1)	-1 dBTP
Broadcast US	-24	-2 dBTP

EBU R128 Standard

Parameter	Value
Target	-23 LUFS
Tolerance	±1 LU
True Peak	-1 dBTP
LRA	Recommended

ATSC A/85 Standard

Parameter	Value
Target	-24 LKFS
Tolerance	±2 LU
True Peak	-2 dBTP
Dialnorm	Metadata

Gating Explained

Gate	Function
Absolute Gate	-70 LUFS (Silence)
Relative Gate	-10 LU below Ungated
Combination	Standard BS.1770-4
Purpose	Relevant Material Only

Loudness Range (LRA)

Value	Interpretation
< 5 LU	Highly Compressed
5-10 LU	Pop, Rock
10-15 LU	Film Average
> 15 LU	Very Dynamic

True Peak

Aspect	Description
Measurement	Oversampling (4x+)
Unit	dBTP
Purpose	Inter-Sample Peaks
Headroom	For Codecs

Measurement Tools

Tool	Description
Youlean Loudness	Free, Precise
WLM Plus (Waves)	Industry Standard
Nugen VisLM	Professional
iZotope Insight	Comprehensive

DAW Integration

DAW	Metering
Pro Tools	Integrated
Nuendo	Supervision
Logic Pro	Loudness Meter
DaVinci Resolve	Fairlight

Workflow

Step	Action
1	Create Mix
2	Measure Integrated
3	Calculate Difference
4	Adjust Gain
5	Check True Peak

Practical Calculation

Measurement	Target	Adjustment
-20 LUFS	-24 LUFS	-4 dB
-28 LUFS	-24 LUFS	+4 dB
-24 LUFS	-24 LUFS	0 dB

Common Mistakes

Mistake	Problem
Measuring Peak Only	Loudness Ignored
Momentary Instead of Integrated	Incorrect Reference
Forgetting True Peak	Codec Issues
No Tolerance	Too Strict

Streaming Normalization

Behavior	Description
Quieter than Target	Will Be Raised
Louder than Target	Will Be Lowered
Within Range	Unchanged
Consequence	Louder ≠ Better

Cinema Context

Aspect	Value
Dialog Normalization	-31 LKFS
Reference Level	85 dB SPL
Measurement	Dialog-Based
Standard	Dolby

Quality Control

Check	Criterion
Integrated	Within Tolerance
True Peak	Below Maximum
Short-term	No Outliers
LRA	Appropriate

Best Practices

Practice	Reason
Know Target Value	Platform-Specific
Prioritize Integrated	Overall Picture
Consider True Peak	Codec Safety
Utilize Tolerances	Don't Over-Optimize

Today

LUFS has established itself as the universal unit for loudness measurement. From broadcast to streaming to cinema – LUFS/LKFS are the common language for consistent audio quality. Understanding this measurement is fundamental for anyone working professionally with audio.

From the crafts

Perspectives

Cinematographer

LUFS sehe ich auf den Audio-Metern in der Post. Als Kameramann muss ich das nicht beherrschen, aber ich verstehe, dass es der Standard für Lautheitsmessung ist.