Change Audio Volume

About changing the volume of an audio file

Some recordings come out too quiet to hear on a phone speaker. Some are so loud they distort in a video. Neither is fixed by turning up the speaker, because the problem is in the file.

Turning the volume up is arithmetic — every sample multiplied by the same number — but two things make it worth a tool rather than a slider in a player:

• The change has to be written into the file, so it travels with it.
• Push it too far and the loudest parts run past what the format can hold, and what was a quiet recording becomes a distorted one.

This shows you the level before and after, and says so when you are about to go too far.

Two ways to set the level

• Set the level myself — a straight volume control, from a whisper to four times as loud. Use it when you know what you want: a backing track under a voice, a recording that just needs a nudge.
• Even it out for me — the tool measures the loudest point in the file and lifts the whole thing until that point reaches the target you set. This is the one to use for a recording that came out too quiet: it works out the right amount for you, and cannot overshoot.

The default target is −1 dB, just under the maximum. Leaving a sliver of room is deliberate — some players and encoders add a fraction on the way out, and a file mastered flat to the ceiling is the one that crackles.

Fading the start and end

A fade in stops a recording from beginning with a click; a fade out is the tidy way to end one that was cut mid-silence. A second or two at each end is usually enough, and both are off by default.

About clipping

Audio has a ceiling. When a multiplied sample would go past it, something has to give, and what usually happens is that the peak is flattened — which is heard as a crackle or a buzz on the loudest words.

When your setting would do that, the page says so before you commit. The tool holds those samples at the maximum rather than letting them wrap around, which is the least bad option, but the real fix is a little less volume.

Evening it out never clips, because it works out the gain from the loudest point in the file.

Nothing is uploaded

The file is read, measured and rewritten in your browser. It never reaches a server, so there is no upload wait and no size limit, and interviews, voice notes, lectures and demos stay on your machine.

The level is measured by decoding the audio here, which is why the "loudest point now" reading appears before you change anything.

What people use it for

• A voice recording that came out too quiet to hear on a phone
• A backing track that needs to sit under a voiceover
• Matching the level of several clips before joining them
• Taking a loud file down so it stops distorting in a video
• Adding a fade to the end of a recording that was cut short
• Making a podcast or lecture audible in a car

Good to know

• The format is kept — an MP3 comes back an MP3, a WAV a WAV
• Changing the level means decoding and re-encoding once, so a lossy file loses a little; work from the original rather than from a file you have already edited
• The reading is the peak, the single loudest instant, not the average — a recording can read close to the ceiling and still sound quiet overall
• Evening out uses the peak, so one loud cough can hold back a whole quiet recording; trim it first with Audio Trim
• To join files after levelling them, use Audio Merger, which also evens out the level between them
• To take out hiss or hum rather than change the level, use Remove Background Noise

How to use it

• Click Click to upload, or drop an audio file onto the box
• Read the loudest point now — that tells you how much room there is
• Choose Set the level myself and move the volume, or Even it out for me and leave it
• Add a fade in or fade out if the ends need it
• Press Apply, listen to the result, then Download audio

Related tools

• Audio Trim — cut the file down first
• Audio Merger — join files and even out the level between them
• Remove Background Noise — hiss, hum and fan noise
• Audio Speed Changer — faster or slower, in tune
• Audio Converter — change the format
• MP3 Tag Editor — fix the title and artist afterwards