Convert WAV to MP3
Turn an uncompressed WAV into an MP3 roughly a tenth the size. WAV stores audio as raw samples with no compression at all, which is why a ten-minute recording runs to a hundred megabytes and will not attach to an email. This is also the one audio conversion where nothing has been lost before you start, so the MP3 you get is a first-generation encode — as good as an MP3 is capable of being.
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Up to 50 MB. Deleted automatically after 30 minutes.
What it does
- A first-generation encode from uncompressed audio
- Typically around a tenth of the original size
- Small enough to email or upload
- No watermark and no sign-up
How to use WAV to MP3
- 1
Add the WAV
Drop the file in or choose it from your computer. The 50 MB limit applies, and WAV files reach it quickly.
- 2
Convert
The samples are encoded to MP3 at a high variable-bitrate setting, which allocates more data to complicated passages and less to simple ones.
- 3
Send it
The MP3 attaches to email, uploads to services with size caps, and plays on every device made in thirty years.
Why WAV files are so large
WAV does almost nothing. It stores audio as a sequence of raw samples — the numbers a microphone's signal was measured as, at whatever rate and precision the recorder used — with a small header describing the format and nothing else.
That is deliberate. WAV was designed in 1991 as a container for uncompressed audio, and it has been the safe interchange format ever since precisely because it makes no decisions on your behalf. Every editor reads it. Nothing is interpreted. There is no encoder whose choices you have to live with.
The cost is size. CD-quality stereo consumes about ten megabytes a minute, and it consumes that whether the passage is a full orchestra or thirty seconds of silence, because the format has no concept of one being simpler than the other.
How it works
The samples are encoded to MP3 at a high variable-bitrate setting. Variable bitrate matters here: rather than spending the same number of bytes on every second, the encoder gives complicated passages more room and quiet or simple ones less. That produces a better result at a given file size than a fixed rate does.
MP3 works by discarding what the ear is unlikely to notice — sounds masked by louder sounds nearby, frequencies at the edges of hearing, detail in passages where a great deal is happening at once. It is not shrinking the audio so much as deciding what not to store.
The one case where MP3 is at its best
Every other audio format converted on this site has already been through a lossy encoder. Converting an AAC, an Ogg or a WMA to MP3 means a second encoder discarding things on top of what a first one already removed, and the two make different choices, so a little extra damage is unavoidable.
WAV has been through nothing. The MP3 you get from one is a first-generation encode working from the original samples, which is the situation MP3 was designed for and the best it can do. If you have ever wondered why some MP3s sound better than others at the same bitrate, this is a large part of the answer.
Keep the original if you made it
A WAV you recorded is a master. Editing, mastering, remixing or converting to any other format later should all start from it, because each of those operations starting from an MP3 inherits the MP3's compromises and adds its own.
A WAV that is simply a copy of something you already have is a different matter, and there is no reason to store both.
Examples
An interview recorded to WAV
Field recorders and voice recorders default to WAV because it is simple and safe. The files are enormous and nothing about speech needs that.
A voice-over for a transcription service
Upload limits are usually the reason. A WAV that exceeds a service's cap becomes an MP3 well under it, with no audible difference for speech.
Frequently asked questions
How much smaller will the file get?
Around ten times, though it varies with the material. A CD-quality stereo WAV uses about ten megabytes per minute regardless of what it contains, because it stores every sample at full precision whether the passage is a symphony or silence. An MP3 of the same minute is usually about one megabyte, because it spends data where the ear notices and skips what it does not.
Will I hear the difference?
For speech, no — not on any equipment, and this is worth saying plainly because people worry about it. For music it depends on the material and on how you listen: at a high variable-bitrate setting most people cannot pick the MP3 out in a fair comparison, and some can on particular passages such as cymbals or applause. Keep the WAV if the recording matters.
Is this a lossy conversion?
Yes, and unusually it is the FIRST lossy step this audio has taken. WAV is uncompressed, so nothing has been discarded before now. That makes this the best case for MP3 encoding — every other audio format on this site is already lossy, so converting it produces a second generation of loss on top of a first.
Should I keep the WAV afterwards?
If it is a recording you made, yes. It is the master, and every future conversion should start from it rather than from the MP3. If it is a copy of something you already have elsewhere, or a file a device produced that you were only going to listen to once, there is no reason to keep both.
Further reading
- Mono at 16 kHz Was a Fifth of Stereo, and at a Fixed Bitrate Nothing ChangedMaking a recording mono is the standard advice for shrinking speech audio, and whether it works depends entirely on a setting most people never touch. Set one way it saves eighty per cent; set the other way it saves nothing at all and quietly improves the quality instead.
- What Each MP3 Bitrate Actually Costs, in BytesAudio bitrate is one of the few compression settings where the size is completely predictable — unlike image quality settings, where the same number produces wildly different files depending on the picture. Here is the same recording at six bitrates plus lossless, and what the predictability means for choosing one.