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LUFS Meter (Loudness Meter)

A loudness meter that applies K-weighting to your microphone and shows momentary (400 ms), short-term (3 s) and integrated loudness in LUFS-style units.

Approximate and relative — not a certified loudness measurement. A browser mic is uncalibrated and the OS may apply automatic gain, this meter is mono / single-channel, and the gating is simplified. Use it to watch loudness change and compare momentary vs short-term — not to certify a file to a spec. For compliant LUFS (ITU-R BS.1770 / EBU R128), measure the file in a proper meter. Nothing is recorded or uploaded.

Microphone

Idle — press Start.

Loudness

MOMENTARYLUFS
-40-30-20-100
Short-term (3 s)
Integrated
Max momentary

What LUFS Means

LUFS (Loudness Units relative to Full Scale) estimates how loud audio sounds to people, not just its raw level. It applies K-weighting — a high-pass plus a high-frequency shelf that mimics the ear’s sensitivity — then measures the mean square energy. Momentary uses a 400 ms window, short-term a 3 s window, and integrated averages the whole program with gating to ignore silence.

This meter implements that idea with real K-weighting filters, but it reads your microphone, which is uncalibrated, mono, and subject to the system’s automatic gain. So the numbers are a useful relative guide — great for seeing loudness rise and fall, or comparing two sources in the same setup — but they are not a certified file measurement.

Why it’s not a substitute for a file meter

Compliant LUFS (for streaming or broadcast) is measured on the actual audio file with calibrated, multi-channel, fully-gated metering. A live mic adds room acoustics, mic response, distance and AGC — none of which belong in a loudness spec. Treat this as a learning and monitoring tool, and measure files in a dedicated meter for real numbers.

Frequently Asked Questions

What’s the difference between momentary, short-term and integrated?
Momentary is a fast 400 ms window (catches moment-to-moment loudness), short-term is a 3 s window (more stable), and integrated is the gated average over the whole session — the single number used for normalization targets.
Are these real LUFS numbers?
They use real K-weighting and the LUFS formula, but from an uncalibrated mono microphone with system AGC — so treat them as approximate and relative, not certified. For compliance, measure the file in a proper BS.1770/R128 meter.
What is K-weighting?
A two-stage filter from ITU-R BS.1770: a high-pass that removes rumble and a high-frequency shelf that boosts treble slightly, approximating how the ear judges loudness before the energy is measured.
Why is my integrated value different from a DAW?
Because this reads a live, uncalibrated mono mic with simplified gating, while a DAW measures the file itself with full multi-channel, two-stage gating. Expect a relative offset, not an exact match.
What target loudness should I aim for?
For files, common targets are about −14 LUFS (most music streaming) or −23 LUFS (EBU broadcast) — use the Loudness Normalization Tool for the gain math. This live meter is for monitoring, not for hitting a file target.
Is my audio recorded?
No. The signal is analyzed in real time to compute loudness and is never recorded, saved, or transmitted. The microphone is released when you press Stop or close the tab.