Make an audio file louder or quieter by an exact number of decibels

How to use the audio volume changer

1. Drop an audio file on the box or press Choose a file. MP3, WAV, M4A, OGG, FLAC, WebM and the sound track of MP4 or MOV videos all work in a current browser.
2. Move the Gain slider: −30 to +30 dB in 0.5 dB steps, starting at +6 dB.
3. Choose Save as. WAV (16-bit, lossless) is the default; for M4A, WebM or OGG also pick a Bitrate (64–320 kbps, default 192).
4. Press Apply gain and download the file. The result also shows Peak after, Peak before, Clipped samples, Length and File size.

What it does and when to use it

This is a volume knob with a number on it. Use it when a voice memo is too quiet on a phone speaker, when a sound effect is far louder than the rest of a video, or when two clips must match by a known amount. A fixed number of decibels can be repeated exactly on several files.

If you just want a recording as loud as it can go without distortion, the audio normaliser works out the gain for you. To cut a section first, use the audio trimmer; to soften an abrupt start or end, add fades.

How it works

The file is decoded in a Web Worker on your device. WAV is read directly; other formats go through the Mediabunny library and your browser’s WebCodecs audio decoder. Every sample is multiplied by 10^(gain ÷ 20), so +6 dB is × 1.995 and −10 dB is × 0.316. The tool measures the highest sample first and adds your gain to predict the new peak. Samples that would pass full scale are limited to ±1 and counted. Nothing is uploaded.

Worked examples

Results from the tool on a 3-second test tone peaking at −12 dBFS:

• +6 dB: Peak before −12 dBFS, Peak after −6 dBFS, Clipped samples 0, saved as voice-+6dB.wav.
• +15 dB: the predicted peak is 3 dB above full scale, so Peak after reads 0 dBFS and 65,640 samples are clipped. The warning asks you to lower the gain by at least 3 dB.
• −10 dB: Peak after −22 dBFS. Turning down never clips.

Limits and tips

• Check Peak before. At −1 dBFS there is almost no room to go louder; a compressor in a desktop editor suits that case better.
• Sample peaks, not true peaks. Lossy formats can overshoot slightly, so leave about 1 dB of space when saving as M4A or OGG.
• Memory. The whole file is held as 32-bit audio, about 21 MB per minute of stereo at 44.1 kHz. Very long files can fail on phones; trim them first or use a desktop browser.
• Browser support. Formats other than WAV need WebCodecs (current Chrome, Edge or Firefox, or Safari 26+). AIFF, AMR, WMA and CAF need the ffmpeg fallback. Firefox and some Linux builds cannot encode AAC, so choose OGG or WAV there.
• To change only the format, use the audio converter.