Audio upload decision guide · Published 28 October 2026

Choose an Audio File Format for Transcription: MP3, M4A, WAV, WebM or OGG

You already have an authorised audio file. Before upload, check its actual format label, the strict 16 MB size ceiling, the separate per-file duration limit, and your remaining minutes. This is pre-upload file-choice help, not a transcription or conversion tool.

Open Audio to Text with an eligible authorised file · Review live plans and limits

Quick answer

For Audio to Text, use an authorised MP3, M4A, WAV, WebM, or OGG file only after it is 16 MB or smaller, fits the applicable per-file duration limit, and fits your remaining minutes. File labels, byte size, running duration, and available minutes are separate checks. Signed-in free accounts receive 15 transcription minutes per calendar month, and no plan or pass overrides the 16 MB ceiling.

Check format, size, duration, and minutes separately

Confirm the actual label. Start with MP3, M4A, WAV, WebM, or OGG. Do not rename an extension and assume that the underlying file changed.
Check the strict 16 MB ceiling. Every transcription upload must be 16 MB or smaller. A plan or pass does not change this file-size rule.
Check duration separately. A small file can still exceed the applicable one-file duration cap; a short file can still be too large.
Check available minutes separately. Check the remaining allowance that applies to your account before upload.

What the labels do and do not tell you

MP3, M4A, WAV, WebM, and OGG are useful input labels, not universal rankings or technical guarantees. MP3 is an audio encoding. M4A commonly refers to audio-only MPEG-4 files. WAVE can wrap different audio bitstreams. WebM and Ogg are containers or encapsulation formats with possible audio codecs. A label alone does not prove the file’s exact codec, size, duration, audio quality, or upload eligibility.

Further reading: Library of Congress MP3 documentation · Library of Congress MPEG-4 documentation · Library of Congress WAVE documentation · WebM Container Guidelines · IETF RFC 5334 Ogg media types.

Fictional size and duration examples

Fictional examples only; not benchmarks or quality estimates: an invented 9-minute MP3 at 7 MB passes the size check but still needs duration and available-minute checks. An invented 9-minute WAV at 54 MB is over the strict 16 MB ceiling even though it is short. An invented 35-minute M4A at 15 MB passes size but still must fit the applicable per-file duration limit and available minutes. No plan or pass overrides the shared 16 MB ceiling.

When a separate file-prep step may help

If an authorised file needs a different format or a smaller size, use Audio File Prep to create a separate downloadable copy. It performs conversion or compression; it does not transcribe, add minutes, change duration rules, or guarantee that a copy qualifies. Check the new file’s actual format, size, duration, and remaining minutes again before choosing Audio to Text.

Keep the next job narrow

For conversion into editable working text from an eligible authorised file, use Audio to Text.
After editable text exists, use the audio transcript QA guide to verify names, numbers, quotations, specialist terms, and unclear speech against original audio.
For the separate learner-made study-notes workflow, read the lecture recording to study notes guide.
For study-specific interview arrangements and identifier questions, read the research interview transcription guide.

Important boundaries

This independent educational guide helps separate pre-upload checks for an authorised file. It does not promise an audio quality level, establish consent or permission, decide sensitive-data suitability, guarantee a preparation output, establish source fidelity, create notes, summarise, correct grammar, remove identifiers, approve ethics/IRB or legal arrangements, or guarantee a transcript result. W3C advises correcting automatically generated transcription against spoken audio; see W3C transcription guidance. University of Bath advises deciding how accuracy will be established; its guidance does not endorse this tool.

Frequently asked questions

Which audio format can I upload for transcription?

Audio to Text currently accepts MP3, M4A, WAV, WebM, and OGG. The file must also be 16 MB or smaller, within the applicable per-file duration limit, and within remaining minutes.

Is WAV too large for Audio to Text?

Not automatically, but a WAV file can exceed the strict 16 MB ceiling. Check the actual file size; no plan or pass overrides that ceiling.

Does a shorter file always fit?

No. Duration and file size are separate checks. A short file can exceed 16 MB, while a smaller file can still exceed the per-file duration limit or remaining minutes.

Can I rename a file extension to make it eligible?

No. Renaming an extension does not change the file's container, codec, size, duration, or technical eligibility.

How many free transcription minutes are available?

The free allowance is 15 minutes per calendar month. This is separate from the per-file duration check and strict 16 MB file-size ceiling. See live plans and limits for current details.