Increase video volume, without clipping

Raise it by a set amount, or to a loudness target

A set amount is counted in decibels: +6 dB doubles the height of the sound wave, and +20 dB multiplies it by ten. It suits a video that is a bit quiet all the way through.

A loudness target works the other way round: you say how loud the result should be, in LUFS, and the tool works out the gain. Loudness is measured the way ITU-R BS.1770 sets out (ITU-R), which weighs the sound roughly as ears hear it and leaves out silent stretches, so one loud bang does not decide the result. A target also turns a file down when it is already louder than the target. Spotify calls this loudness normalization.

Either way, the tool measures your file first and shows its loudness and loudest peak, so you see what a choice will do before anything is written. On our test files, its readings matched those of FFmpeg's EBU R 128 meter to within 0.1 LU.

Loudness targets, and who asks for them

YouTube's recommended upload settings give codecs, channels and sample rates for sound, but no loudness target (YouTube Help). For a video you share online, -14 LUFS is a common middle; for speech, -16 LUFS is plenty.

How the limiter stops clipping

Making a sound louder makes its peaks louder too, and a peak above the top of the scale is cut flat, which sounds harsh. So after the gain comes a limiter: it looks 5 milliseconds ahead, turns the sound down smoothly just before a peak, and lets it back up over about 150 milliseconds. It keeps every sample at or below -2 dBFS, or -3 dBFS in an Opus file, whose encoder lifts sharp peaks a little more. In our tests the true peaks of the new files, between the samples and after encoding, stayed at -1 dB or lower in every format.

A limiter makes the loudest moments quieter, which would leave a file under a loudness target. So when the limiter will be busy, the tool tries the gain first without writing anything, measures the result and corrects the gain, at most twice. Our test video aimed at -14 LUFS measured -14.2 LUFS in FFmpeg, with its true peak at -1.1 dB.

A very big boost needs a lot of limiting, and the loudest moments then sound flattened. The note warns you when peaks would pass the limit by more than 6 dB; a smaller boost keeps more of their punch.

The picture is not touched

Only the sound is decoded and encoded again; the video picture is copied packet for packet. In our tests the picture of an H.264 MP4, a VP9 WebM and an iPhone-style HEVC MOV turned on its side came out identical, with the rotation kept.

An MP4 or MOV comes back as an MP4 with AAC sound at about the bitrate of the original, from 96 to 192 kbps; a WebM stays a WebM with Opus sound. Because the picture is never decoded, an HEVC video works even in a browser that cannot show its picture.

Louder in the file, not only on your speaker

A volume booster extension, or the volume buttons, change how loud a video plays on your own device. Anyone you send the video to still gets the quiet file. This tool writes the louder sound into a new file, so the extra volume goes with it when you send it in a chat, post it, or play it on a TV or in a presentation.

MP3 and other sound files keep their format

The same tool raises the volume of an MP3, M4A, WAV, OGG, OPUS or FLAC file. An MP3 stays an MP3 at its own bitrate, AAC stays AAC, WAV keeps its bit depth and FLAC stays lossless. Ogg Vorbis comes back as Opus in an .ogg file, because browsers cannot write Vorbis.

Very quiet recordings

A loudness target never adds more than 30 dB. Past that, a recording is mostly hiss, and raising it makes the hiss loud too; the note says when the target would need more. A file that is silent, or quieter than -70 LUFS all the way through, cannot be measured, and the tool says so.

Raising the volume raises everything in the recording by the same amount: voices, hiss, wind and room echo alike. It makes a recording louder, not cleaner, and it does not remove background noise.

On an iPhone or Android phone

Open this page in Safari 26 or later on an iPhone, or in Chrome on Android, tap Choose a video or audio file and pick the video. Measuring and writing use the phone's own processor, so keep the page open until it finishes. On an iPhone the louder copy lands in the Downloads folder of the Files app (Apple); on Android, open the Files app to find it (Google).

A phone holds the new video in memory before you download it, which is easy up to about 200 MB. For a longer video, shorten it first with cut video, or use a computer.

Your video stays on your device

The file is read and measured inside your browser and never uploaded. Measuring decodes the sound once and writing decodes it again; in our test, writing the louder copy of a 20-second video took under a second. The new file carries no title, location or recording date from the original. Chrome and Edge on a computer write a file over 500 MB straight to disk instead of holding it in memory. Changing the sound needs sound decoding on the device: Chrome and Edge from version 94, Firefox on computers from 130, Samsung Internet from 17 and Safari from 26 (caniuse).