100 KB M4A sample file
An M4A file of exactly 102,400 bytes. It is a valid MPEG-4 audio file, generated for this site and checked with an independent parser. Use it wherever you need a 100 KB sample, test or dummy M4A file.
Download
sample-m4a-100kb.m4a
100 KB102,400 bytes
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- Type
- audio/mp4
- SHA-256
d699e8175a394806eca2b28864daa10e736d1f81c036257a7e242c9f284c246d- Direct URL
https://www.sampletestfiles.com/downloads/m4a/sample-m4a-100kb.m4a
What is in this file
272 AAC frames (6.3 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 254 bytes of a trailing "free" box bring the file to the exact size.
| Duration | 6.3 s |
|---|---|
| Audio codec | AAC-LC |
| Bit rate | 128 kbit/s |
| Sample rate | 44,100 Hz |
| Channels | Stereo |
| Container | MPEG-4 (brand "M4A ") |
| Fast start | Yes (moov before mdat) |
First bytes of the file
The first 64 bytes of sample-m4a-100kb.m4a as a hex dump: offset, bytes, then the same bytes as text. The M4A signature is 66 74 79 70 4D 34 41 20 at offset 4.
00000000 00 00 00 1c 66 74 79 70 4d 34 41 20 00 00 02 00 |....ftypM4A ....|
00000010 4d 34 41 20 6d 70 34 32 69 73 6f 6d 00 00 06 68 |M4A mp42isom...h|
00000020 6d 6f 6f 76 00 00 00 6c 6d 76 68 64 00 00 00 00 |moov...lmvhd....|
00000030 00 00 00 00 00 00 00 00 00 00 03 e8 00 00 18 ac |................|Preview
Displays the file in your browser.
Where 100 KB matters
A 102,400-byte file that sits exactly on the default request-body limit of Express. These are the default limits a file of this size is useful for testing:
| System | Limit | Note |
|---|---|---|
| Express body parsers | 100 KB (102,400 bytes) by default | A request body of exactly this size passes; anything larger returns 413 Payload Too Large. |
| Gmail message clipping | About 102 KB of HTML | Longer messages are truncated behind a "view entire message" link. |
| Amazon DynamoDB items | 400 KB per item | 100 KB fits; the 500 KB sample does not. |
Use this file for
- Checking email size handling
- Checking podcast and audiobook pipelines
- Verifying type detection between audio and video MP4
Testing notes for M4A
- Three media types are in circulation: audio/mp4, audio/x-m4a and audio/m4a. Browsers send different ones for the same file.
- The container is the same as MP4 video, so content sniffers often report video/mp4. Telling them apart takes a look at the ftyp brand or at the tracks.
Technical details
| File name | sample-m4a-100kb.m4a |
|---|---|
| Format | M4A (MPEG-4 audio) |
| Extension | .m4a |
| MIME type | audio/mp4 |
| Size | 102,400 bytes (100 KB) |
| Kind | Binary |
| Signature | 66 74 79 70 4D 34 41 20 at offset 4 |
| SHA-256 | d699e8175a394806eca2b28864daa10e736d1f81c036257a7e242c9f284c246d |
| Created | 2026-10-10 |
| Validation | Exact size, signature bytes and structure checked when the file was generated |
| Preview | Available on this page |
| Source | Generated for this site; not copied from elsewhere |
| Licence | Free to use, modify and redistribute (terms) |
| Category | Audio |
Validated for expected format and integrity. As with any download, scan the file with your own security tools before opening it. How files are made and checked
Download from the command line and verify
Fetch the file with curl, then compare its checksum with the SHA-256 value above.
curl -o sample-m4a-100kb.m4a 'https://www.sampletestfiles.com/downloads/m4a/sample-m4a-100kb.m4a'
sha256sum sample-m4a-100kb.m4a # Linux
shasum -a 256 sample-m4a-100kb.m4a # macOSOn Windows, run Get-FileHash sample-m4a-100kb.m4a -Algorithm SHA256 in PowerShell. A matching value proves that the download is complete and unaltered.
Related files
Questions about this file
- Is this file exactly 100 KB?
- Yes. It is 102,400 bytes, which is 100 KB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
- What is inside the 100 KB M4A file?
- 272 AAC frames (6.3 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 254 bytes of a trailing "free" box bring the file to the exact size.
- Is an M4A file the same as an AAC file?
- Not quite. M4A is AAC inside an MP4 container, with an index that allows seeking. A file ending in .aac is a bare stream of AAC frames with a small header on each and no index.