WAV to text
The one supported format where the size limit is a real obstacle — and the one where converting before upload is worth doing.
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In short
You can upload WAV files without converting them, but the arithmetic is worth knowing: WAV is uncompressed, so an hour of 44.1 kHz stereo is about 635 MB and just over 8 hours fit in the 5 GB limit. For anything longer, convert to 128 kbps MP3 — transcription accuracy will not change.
How much an hour of WAV weighs
WAV stores raw samples, so its size follows directly from the recording parameters and does not depend on what is on the tape. The formula is simple: sample rate × bit depth × channels.
| Parameters | Typical source | Per hour | Fits in 5 GB |
|---|---|---|---|
| 16 kHz, 16-bit, mono | dictaphone, call recording | 115 MB | ~46 h |
| 44.1 kHz, 16-bit, mono | single-microphone recorder | 318 MB | ~17 h |
| 44.1 kHz, 16-bit, stereo | CD standard, default export | 635 MB | ~8 h |
| 48 kHz, 24-bit, stereo | studio session, film equipment | 1.04 GB | ~5 h |
Scroll the table sideways to see the remaining columns.
When to convert, and when not to
There is one rule, and it follows from how speech recognition works: the model analyses the speech band, not sonic fidelity. A WAV's surplus quality does not buy a single additional correctly recognised word.
- Upload as-is if the file fits in 5 GB and your connection is fast — that is the simplest route.
- Convert to 128 kbps MP3 if the recording runs to several hours or the upload drags. The file shrinks about elevenfold.
- Do not convert to another lossless format such as FLAC. We take it happily, but the file does not shrink enough to make the conversion worth it.
- Do not resample below 16 kHz. Under that threshold you start removing information the model genuinely works with.
Where WAV files come from
- Field and studio recorders, where WAV is the default capture format.
- Call-recording systems — often 16 kHz mono, the lightest row in the table.
- Equipment used for hearings and council sessions, where lossless capture is sometimes a procedural requirement.
- Exports from audio editing software, usually 44.1 or 48 kHz.
If WAV is an archival requirement on your side, keep the original and send an MP3 copy for transcription. The transcript will be identical and the upload many times shorter.
Questions
How many hours of WAV fit in the limit?
At 44.1 kHz 16-bit stereo, just over 8 hours, since an hour is around 635 MB. At 16 kHz mono, typical of dictaphones, around 46 hours. This is the only supported format where the limit is a real problem.
Does WAV give a more accurate transcript than MP3?
At typical compression settings, no. The model works on the speech band rather than sonic fidelity, so recording conditions matter incomparably more than the format. A difference only appears at very low bitrates.
How do I shrink a WAV before uploading?
Export it to 128 kbps MP3 in any audio editor — the file shrinks roughly elevenfold and the transcript comes out the same. Do not resample below 16 kHz.
Do you support FLAC?
Yes, upload it as it is, the same as a WAV. Losslessness does not make the transcript any better, so convert only when you want a faster upload: 128 kbps MP3 gives the same text from a file an order of magnitude smaller.