Audio Loudness Meter
Measure the integrated loudness (LUFS) of any audio file using EBU R128 standards. Get the integrated loudness, true peak level, and loudness range. Essential for mastering, podcast publishing, and broadcast compliance.
About Audio Loudness Meter
Measure the integrated loudness (LUFS) of any audio file using EBU R128 standards. Get the integrated loudness, true peak level, and loudness range. Essential for mastering, podcast publishing, and broadcast compliance.
All analysis happens entirely inside your browser using the Web Audio API. Your audio file never leaves your device — there is no upload, no account, no tracking. Closing the tab fully erases the file from memory.
Browser-based audio analysis trades a little speed for total privacy. Server tools can crunch big lossless files faster on dedicated CPUs, but they require uploading your file. Here, decoding and analysis run on the same hardware you're holding.
Related tools
About Audio Loudness Meter
Audio Loudness Meter is the kind of utility you bookmark and reach for when you need it. Measure the integrated loudness (LUFS) of any audio file using EBU R128 standards. Get the integrated loudness, true peak level, and loudness range. Essential for mastering, podcast publishing, and broadcast compliance. It loads quickly, works on any modern browser, and produces a result you can download or copy in a single click.
Audio Loudness Meter fits naturally into the workflow of language learners reviewing speech and musicians sharing demos, both of whom typically need a fast result inside the browser. There is no learning curve to budget for: anyone who has used a typical web upload form can complete a run on the first try.
Most people land on Audio Loudness Meter via a search at the moment they actually need the tool. That shapes the design: the page is a single screen with the input on one side, the controls in the middle, and the result on the other, so a first-time visitor can complete the job without reading documentation.
The processing pipeline is straightforward: your input is parsed by standard browser APIs, transformed according to the options you select, and serialised back into a downloadable result. Accepted input formats are MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA. The 200 MB per-file ceiling matches what a typical browser tab can handle without paging to disk.
Because everything runs in the page, the tool scales the same way for one user or a million — there is no per-user backend cost. The page is static, the engine is the same JavaScript bundle for every visitor, and the work happens on the visitor's own device. That keeps the tool free and keeps it fast on the first interaction.
Audio Loudness Meter is intentionally narrow in what it does, which makes it easy to slot into a longer workflow. Take its output, hand it to whichever next tool fits the job, and Audio Loudness Meter stays out of your way until the next time you need it.
A practical note on limits: Audio Loudness Meter accepts inputs up to 200 MB per run, and the tool processes one input at a time to keep memory usage predictable. If you ever bump into the ceiling, the cause is the size of the input.
Some notes on the design of Audio Loudness Meter. The page is intentionally narrow: one input, the controls relevant to the task, and one output. Adding unrelated features would make the common case slower for the majority of users, so the surface is held to what people actually use.
Output handling is intentionally boring: Audio Loudness Meter produces `{name}-edited.{ext}` and triggers your browser's standard "save" behaviour. If you have a default download folder configured, that is where it will land. There is no Favtoo-side history of jobs you have run.
From a product perspective, Audio Loudness Meter is one of the simplest possible expressions of "do one thing well." The catalog contains dozens of related tools that each handle a slightly different audio editing and conversion task, and every one is a separate page rather than a tab inside a larger app. That separation keeps each tool fast to load and easy to bookmark.
Audio Loudness Meter is built around the moment of need: a focused page you open when you have a specific task, complete the task, and close. The catalog contains many adjacent tools so the same model serves the surrounding parts of a typical audio editing and conversion workflow.
Useful patterns when working with Audio Loudness Meter: keep the input file open in another tab so you can compare against the result; give the output file a descriptive name when saving so you can find it later (the default name is sensible but generic); and treat each run as independent — the tool has no concept of "history", which means you cannot accidentally pollute one job with leftovers from another.
If Audio Loudness Meter appears to hang, the engine is almost certainly still working — large inputs simply take longer to process inside a browser than they would on a server with multi-core scheduling. For inputs near the 200 MB cap, give it up to a minute on a typical laptop before assuming something is stuck.
If Audio Loudness Meter solved your problem, sharing the page link with someone who has the same problem is the most useful thing you can do. The catalog grows mostly through word of mouth; visitors arriving through a recommendation tend to be the ones the tool serves best.
How it works
- 1Open Audio Loudness Meter in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Drop a MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA file onto the upload area, or click to pick one from your device.
- 3Tweak the controls if the defaults are not quite right for your input. The options are kept short and labelled in plain language.
- 4Click to start the job. The engine (standard browser APIs) processes the input in the page; you can watch the progress indicator until it completes.
- 5Save the output (`{name}-edited.{ext}`) when it is ready.
- 6Repeat the process for additional inputs whenever you need to. The page stays loaded, so subsequent runs are quick.
Common use cases
- Extract the audio from a video so it can be edited separately using Audio Loudness Meter.
- Boost a quiet interview recording to a normal listening level.
- Normalise loudness across an episode so listeners do not reach for the volume.
- Stitch several voice notes into a single playable file.
- Convert a voice memo into a format your editor can open.
- Trim the cough out of the first ten seconds of a podcast take.
- Record a quick test tone to verify a microphone setup.
- Convert a band's rough mix into a format mastering software accepts.
- Compress a music demo small enough to share over messaging.
FAQ
What is LUFS and why does it matter?
LUFS (Loudness Units Full Scale) is the modern standard for measuring perceived loudness, used by Spotify, YouTube, Apple Music, Amazon, and major broadcasters. Unlike peak measurement, LUFS accounts for how loud the audio actually feels — it's the most accurate way to ensure consistent loudness across tracks.
How does the meter work?
FFmpeg WebAssembly's `loudnorm` filter analyzes your file in EBU R128 mode (the broadcast standard). It computes integrated loudness (the average across the whole file), true peak (the highest instantaneous level), and loudness range (how much the loudness varies). All values use industry-standard units.
What's a good loudness target?
-14 LUFS for Spotify, YouTube, Tidal, Amazon Music. -16 LUFS for Apple Podcasts. -23 LUFS for European broadcast TV. -24 LUFS for US broadcast TV. Modern streaming platforms apply automatic loudness normalization, so files much louder than -14 LUFS are turned down (potentially with worse sound than if you'd targeted -14 yourself).
Why does my "loud" master measure -8 LUFS?
Many commercially mastered tracks (especially mainstream pop and EDM from the 2010s) measure -8 to -6 LUFS — extremely loud. Streaming platforms turn these down to match a -14 LUFS target, which can result in worse perceived sound vs a track mastered at -14 LUFS in the first place. Normalize for the platform target instead.
What's "true peak" and why does it matter?
True peak (dBTP) accounts for inter-sample peaks — peaks that exceed the digital ceiling between sample boundaries. A file may show 0 dB peak on a normal meter but +1 dBTP on a true-peak meter, which would clip on lossy encoders or analog playback. Pros target -1 dBTP max to leave headroom.
How big a file can I measure?
Up to 200MB. Measurement is a single-pass loudness analysis; expect roughly 0.5× real-time on a modern desktop (a 5-minute file measures in about 2.5 minutes).
Why is in-browser audio processing slower than online tools?
Server-side tools use multi-threaded native FFmpeg running on dedicated CPUs with fast disks and parallel pipelines. Our engine is FFmpeg compiled to WebAssembly, which runs single-threaded inside your browser tab and has no access to native hardware acceleration. That makes browser-based jobs typically 3–8× slower than a server. The trade-off is total privacy: your audio file is never uploaded, never logged, and never stored — closing the tab erases everything from memory immediately. For most clips up to a few minutes the wait is small, and for sensitive recordings (voice memos, drafts, confidential meetings) the privacy gain is well worth it.
Is my audio uploaded?
No. Everything runs entirely inside your browser tab using FFmpeg compiled to WebAssembly. The file is read into local memory only, processed in the same tab, and the result is offered as a direct download. Nothing is transmitted to any server, no account is required, no analytics are tied to your file, and closing the tab discards every byte from memory.
How big a file can I process?
The file picker accepts audio inputs up to about 1 GB, which is well above what mainstream "free tier" online converters allow. The real ceiling is your device — everything runs inside your browser tab, which shares memory with the rest of the page. Most podcasts, songs, and voice memos sit comfortably under that limit even on a phone. If a very large lossless WAV or FLAC ever fails, trim it first or transcode to MP3 / Opus to bring the size down before re-running the tool.
Which audio formats are supported?
MP3, WAV, OGG (Vorbis and Opus), FLAC, M4A (AAC), AAC, Opus, AIFF, and WMA all decode reliably via FFmpeg WASM. Output formats depend on the specific tool — most editing tools default to MP3 (universal) or WAV (lossless) but expose a format picker so you can pick the one that fits your downstream player or DAW.
Which browsers are supported?
Recent Chrome, Edge, Firefox, Safari, and other Chromium-based browsers all work. The tool relies on WebAssembly and SharedArrayBuffer, which require the page to be served over HTTPS with the right cross-origin headers — this site is configured correctly by default. On phones the same code runs but is slower than on a desktop because mobile CPUs are weaker.
Is there a watermark, sign-up wall, or usage cap?
No. The tool is completely free, requires no account, attaches no watermark, applies no usage caps, and shows no popup ads on your output. Because the work happens on your own device, there is no per-user quota for us to enforce — your hardware and browser memory are the only limits. The download is the file you would get from running FFmpeg locally, nothing more, nothing less.
Can I trust the output of Audio Loudness Meter for important work?
Audio Loudness Meter is built on standard browser APIs, which is the same class of engine used by professional audio editing and conversion pipelines. For deterministic operations, the output is byte-identical to what an equivalent CLI run would produce; for operations involving a codec or a model, the result is well within the range of what comparable tools generate. If you have a specific reference output you need to match, run a small test job first to confirm the configuration produces what you expect.
How often is Audio Loudness Meter updated?
Audio Loudness Meter is updated whenever the underlying engine releases an improvement or a bug fix. Because the tool is delivered as a static page, every visit fetches the latest version automatically — there is no "version" to manage on your end. If a particular release ever changes default behaviour, the change is documented on Favtoo's changelog so you can confirm what shifted.
Which browsers are supported by Audio Loudness Meter?
Audio Loudness Meter works in any modern browser released in the last few years — Chrome, Edge, Firefox, Safari, Brave, Arc and the major Chromium derivatives are all supported. The underlying engine relies on widely-supported web APIs, so there is nothing exotic to install. If you are on a very old browser version and the tool fails to load, updating to the latest release of your preferred browser is the only fix needed.
What input formats are supported by Audio Loudness Meter?
Audio Loudness Meter accepts MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA. If your input is in a format that is not directly supported, convert it first using one of Favtoo's converter tools — every Favtoo converter outputs a file that is a clean input to the next tool in the chain.
Does Audio Loudness Meter have an API?
Audio Loudness Meter is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.
Will Audio Loudness Meter keep working if my Wi-Fi drops mid-task?
Once the page is loaded, Audio Loudness Meter can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
Is Audio Loudness Meter really free?
Audio Loudness Meter is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.