1 MB M4A sample file
An M4A file of exactly 1,048,576 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 1 MB sample, test or dummy M4A file.
Download
sample-m4a-1mb.m4a
1 MB1,048,576 bytes
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- Type
- audio/mp4
- SHA-256
6e78319a02ca5ba7a52b38d6acbb47c81c9d24be6ee06ed7d915d69f4ad5eae2- Direct URL
https://www.sampletestfiles.com/downloads/m4a/sample-m4a-1mb.m4a
What is in this file
2,805 AAC frames (1 min 5 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 230 bytes of a trailing "free" box bring the file to the exact size.
| Duration | 1 min 5 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-1mb.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 2d fc |M4A mp42isom..-.|
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 fe 6c |...............l|Preview
Displays the file in your browser.
Where 1 MB matters
A 1,048,576-byte file: exactly the default upload limit of nginx, Spring Boot and Next.js. These are the default limits a file of this size is useful for testing:
| System | Limit | Note |
|---|---|---|
| nginx | 1 MB by default (client_max_body_size) | A multipart upload of this file exceeds the limit by the size of the form boundaries. |
| Spring Boot multipart | 1 MB per file by default (max-file-size) | A file of exactly 1 MB is at the limit. |
| Next.js API routes and Server Actions | 1 MB by default | Larger bodies need the size limit raised in configuration. |
| Cloud Firestore documents | 1 MiB (1,048,576 bytes) | The same number of bytes as this file. |
| Apache Kafka messages | About 1 MB by default | Brokers reject larger records unless message.max.bytes is raised. |
Use this file for
- Finding the first upload limit in a new stack
- Testing audio uploads from iPhones, which record voice memos as M4A
- Checking podcast and audiobook pipelines
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-1mb.m4a |
|---|---|
| Format | M4A (MPEG-4 audio) |
| Extension | .m4a |
| MIME type | audio/mp4 |
| Size | 1,048,576 bytes (1 MB) |
| Kind | Binary |
| Signature | 66 74 79 70 4D 34 41 20 at offset 4 |
| SHA-256 | 6e78319a02ca5ba7a52b38d6acbb47c81c9d24be6ee06ed7d915d69f4ad5eae2 |
| 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-1mb.m4a 'https://www.sampletestfiles.com/downloads/m4a/sample-m4a-1mb.m4a'
sha256sum sample-m4a-1mb.m4a # Linux
shasum -a 256 sample-m4a-1mb.m4a # macOSOn Windows, run Get-FileHash sample-m4a-1mb.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 1 MB?
- Yes. It is 1,048,576 bytes, which is 1 MB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
- What is inside the 1 MB M4A file?
- 2,805 AAC frames (1 min 5 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 230 bytes of a trailing "free" box bring the file to the exact size.
- Which codec do the M4A samples use?
- AAC-LC at 128 kbit/s, 44,100 Hz stereo, which is the combination every device and browser plays.