3 MB M4A sample
An M4A file of exactly 3,145,728 bytes. It is a valid MPEG-4 audio file, generated by this site. Compare its checksum and test it with the parser used by your application. Use it wherever you need a 3 MB sample, test or dummy M4A file.
Download
sample-m4a-3mb.m4a
3 MB3,145,728 bytes
Download 3 MB M4ACreated in your browser in a few seconds, then checked against the SHA-256 checksum. The file is not uploaded anywhere. No sign-up.
- Type
- audio/mp4
- SHA-256
7b9e35a7e674b101f81ad6d635b0ca5e53f66ebfa547e6669a399e35d0ea533f- Delivery
- Created in your browser from static generator assets (how it works).
What is in this file
8,413 AAC frames (3 min 15 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 21 bytes of a trailing "free" box bring the file to the exact size.
| Duration | 3 min 15 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-3mb.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 88 b4 |M4A mp42isom....|
00000020 6d 6f 6f 76 00 00 00 6c 6d 76 68 64 00 00 00 00 |moov...lmvhd....|
00000030 e5 7b 69 80 e5 7b 69 80 00 00 03 e8 00 02 fb 15 |.{i..{i.........|Preview
Creates the file in your browser and shows it here.
Where 3 MB matters
A 3,145,728-byte file, 3 MB in the binary units that operating systems and upload limits use. It is useful wherever a form, an API gateway, a storage quota or a mail server is configured with a limit of about this size.
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-3mb.m4a |
|---|---|
| Format | M4A (MPEG-4 audio) |
| Extension | .m4a |
| MIME type | audio/mp4 |
| Size | 3,145,728 bytes (3 MB) |
| Kind | Binary |
| Signature | 66 74 79 70 4D 34 41 20 at offset 4 |
| SHA-256 | 7b9e35a7e674b101f81ad6d635b0ca5e53f66ebfa547e6669a399e35d0ea533f |
| Created | 2026-10-23 |
| Validation | See the listed size and SHA-256. Small downloads are checked in the browser; verify streamed downloads manually. A hash match does not prove parser compatibility. |
| Preview | Available on this page |
| Source | Generated in your browser by this site's generator; not copied from elsewhere |
| Licence | Free to use, modify and redistribute (terms) |
| Category | Audio |
Check the stated structure and checksum against your application requirements. As with any download, scan the file with your own security tools before opening it. How files are made and checked
Verify your copy
This file is created in your browser, so it has no direct URL for curl or wget. The generator is designed to produce reproducible bytes. After saving, compare the checksum with the SHA-256 value above.
sha256sum sample-m4a-3mb.m4a # Linux
shasum -a 256 sample-m4a-3mb.m4a # macOSOn Windows, run Get-FileHash sample-m4a-3mb.m4a -Algorithm SHA256 in PowerShell. For scripts and pipelines, save the file once and keep your own copy.
Related files
Questions about this file
- Is this file exactly 3 MB?
- Yes. It is 3,145,728 bytes, which is 3 MB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
- What is inside the 3 MB M4A file?
- 8,413 AAC frames (3 min 15 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 21 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.