Make an audio file smaller
Type the size you have to hit and the bitrate is solved for you, with the predicted result shown before anything runs. Or ignore that and pick a bitrate yourself. Either way it happens in this tab.
Make it smaller
Name a target in MB, or choose a bitrate. The predicted size appears first.
Starting the converter…
Naming a size instead of guessing a bitrate
Most compressors hand you a bitrate slider and leave you to work backwards. That is the wrong way round, because you almost never arrive wanting 96 kbps — you arrive because something has a limit and your file is over it. An email attachment. A submission form. A transcription service.
So type the size. A constant-bitrate encode of a known length has a predictable size, so the arithmetic runs in reverse: the bitrate that fits is chosen, and the size it will produce is shown before you commit. There is no guessing and no converting twice to see if it worked.
It also tells you when the answer is no. A four-minute recording cannot become 200 KB at any bitrate on offer — the readout says so, gives the smallest size actually reachable, and suggests trimming instead. A slider would have let you drag to the bottom and hand back something still too big.
Cutting thirty seconds of dead air off the front removes those bytes completely, while lowering the bitrate degrades every second of what is left. Do the free thing first: trim it, then come back and see whether it still needs shrinking.
There are only three levers, and one of them is free
| Lever | Typical saving | What it costs |
|---|---|---|
| Trim the parts you do not need | However much you cut | Nothing. The rest is untouched |
| Fold stereo to mono | About half | The stereo image. Nothing at all on one speaker |
| Lower the bitrate | Proportional | Detail, across the whole recording |
For a spoken-word recording, all three together take a file to roughly a quarter of its size and nobody notices. For music, mono is usually off the table and trimming rarely applies, so the bitrate is the only real lever — which is why music does not shrink nearly as well as speech.
Speech and music need different numbers
A one-hour recording at each setting, to give the decision some scale:
| Bitrate | One hour, stereo | One hour, mono | Suitable for |
|---|---|---|---|
| 64 kbps | 27 MB | about 14 MB | Speech, when size rules everything |
| 96 kbps | 41 MB | about 21 MB | Speech, comfortably |
| 128 kbps | 55 MB | about 27 MB | Music that has to stay small |
| 192 kbps | 82 MB | about 41 MB | Music, general purpose |
| 320 kbps | 137 MB | — | Archiving. Rarely worth it for sharing |
The pattern worth taking away: a one-hour interview at 96 kbps mono is about 21 MB, which fits in an email. The same interview at 192 kbps stereo is about 82 MB, which does not — and sounds no better, because it is one person talking.
What compression cannot do
Making a file smaller means throwing audio away. Every honest description of this ends there. A converter promising a smaller file at the same quality is either not compressing it or not telling you the truth.
Two specific things worth knowing:
- Re-compressing a compressed file stacks the damage. An MP3 taken from 320 to 96 has been through two encoders. It is still the right move when you need it smaller, but go back to the original if you have one.
- Nothing here re-inflates. Once it is at 96 kbps, converting back up to 320 makes a larger file containing the same audio, slightly worse.
When something looks smaller for free, it is usually because nothing was re-encoded at all — the audio was simply re-wrapped. That is real, and this converter does it where it can, but it does not make anything smaller.
The exception: uncompressed sources
If the file is a WAV or an AIFF, you are in the best case. Uncompressed audio is roughly 10 MB per minute, and compressing it for the first time is where the enormous savings are: a ten-minute WAV is about 100 MB, and the same recording at 96 kbps mono is about 3.5 MB. That is a thirtyfold reduction on the audio's first lossy pass, which is exactly what these formats were invented for.
Step by step
Load the file
Its real length, bitrate and channel count are read out of the file, because all three decide what is possible.
Say how small it has to be
Type a size in megabytes. The bitrate that gets there is chosen and the predicted result is shown immediately — including when the target cannot be reached.
Fold to mono if it is speech
One speaker does not need two channels. This roughly halves the file again and costs nothing you would notice.
Convert and check
The finished size appears next to the original. In testing, a 9.2 MB file with a 3 MB target came out at 2.7 MB.
About shrinking audio
How do I make an audio file a specific size?
Type the size in the box above. The bitrate that lands on it is worked out from the recording's length and the predicted result is shown before anything runs. In testing, a 9.2 MB file with a 3 MB target came out at 2.7 MB.
Learn moreWhat if the target is too small to reach?
It tells you, rather than converting and disappointing you. The readout gives the smallest size actually reachable at the lowest bitrate on offer and suggests trimming instead, which is the only other way to get there.
Learn moreDoes compressing lose quality?
Yes. Making a file smaller means discarding audio — that is what compression is. For speech at 96 kbps you will not hear it; for music at very low bitrates you will. Anything claiming a smaller file at identical quality is not compressing it.
Learn moreShould I fold it to mono?
For one person talking, yes — it roughly halves the file and there is nothing to lose. For music, no: it collapses the stereo image permanently. The toggle is above, and it is the biggest saving available on a spoken-word recording after trimming.
Learn moreWhat is the fastest way to get under Gmail's limit?
Trim the dead air, fold to mono if it is speech, then set a target of about 18 MB. Gmail's stated 25 MB is roughly 18 MB of real file once it is encoded for transit, so aiming at 25 leaves you bouncing.
Learn moreCan I shrink several files at once?
Yes. Select as many as you like and the same settings are applied to each, with its own download at the end. A target size is solved against the longest file so that none of them overshoot it.
Learn more