500 KB M4A sample file

An M4A file of exactly 512,000 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 500 KB sample, test or dummy M4A file.

sample-m4a-500kb.m4a

500 KB512,000 bytes

Download 500 KB M4A

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Type: audio/mp4
SHA-256: 0de4be73ec6bd68d110216954b6a5c2bf10b4b038f2733a603258f2150f73838
Direct URL: https://www.sampletestfiles.com/downloads/m4a/sample-m4a-500kb.m4a

What is in this file

1,368 AAC frames (31.8 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 104 bytes of a trailing "free" box bring the file to the exact size.

Duration	31.8 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-500kb.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 17 88  |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 7c 15  |..............|.|

Preview

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Where 500 KB matters

A 512,000-byte file: larger than most API body limits, smaller than most upload limits. These are the default limits a file of this size is useful for testing:

System	Limit	Note
Amazon DynamoDB items	400 KB per item	500 KB cannot be stored as a single item.
Express body parsers	100 KB by default	Rejected unless the limit is raised.
nginx request body	1 MB by default (client_max_body_size)	Accepted with room to spare.

All 500 KB sample files

Use this file for

Typical image-upload tests
Testing transcoding to MP3 or Opus
Testing audio uploads from iPhones, which record voice memos as M4A

Testing notes for M4A

AAC encoders add a short run of priming samples before the real audio. Players that do not account for it report a slightly longer duration and leave a gap between tracks that should join seamlessly.
Three media types are in circulation: audio/mp4, audio/x-m4a and audio/m4a. Browsers send different ones for the same file.

M4A format reference

Technical details

File name	sample-m4a-500kb.m4a
Format	M4A (MPEG-4 audio)
Extension	.m4a
MIME type	audio/mp4
Size	512,000 bytes (500 KB)
Kind	Binary
Signature	66 74 79 70 4D 34 41 20 at offset 4
SHA-256	0de4be73ec6bd68d110216954b6a5c2bf10b4b038f2733a603258f2150f73838
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-500kb.m4a 'https://www.sampletestfiles.com/downloads/m4a/sample-m4a-500kb.m4a'
sha256sum sample-m4a-500kb.m4a     # Linux
shasum -a 256 sample-m4a-500kb.m4a # macOS

On Windows, run Get-FileHash sample-m4a-500kb.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 500 KB?: Yes. It is 512,000 bytes, which is 500 KB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
What is inside the 500 KB M4A file?: 1,368 AAC frames (31.8 s) of a synthesised musical phrase that repeats every eight seconds, in one audio track. 104 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.

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