20 MB ZIP sample file

A ZIP file of exactly 20,971,520 bytes. It is a valid ZIP archive file, generated for this site and checked with an independent parser. Use it wherever you need a 20 MB sample, test or dummy ZIP file.

sample-zip-20mb.zip

20 MB20,971,520 bytes

Download 20 MB ZIP

Created in your browser in a few seconds, then checked against the SHA-256 checksum. No sign-up.

Type: application/zip
SHA-256: 05ec99adb50d2d23b4eeb5d677acab7ff37086435bfbd63e992a44ead7c36d42
Delivery: Created in your browser. Files of 2 MB and more have no direct URL (why).

What is in this file

4 entries: a README, a CSV file and a JSON file compressed with deflate, plus payload.bin, 20,967,670 pseudo-random bytes stored without compression so the archive is exactly 20,971,520 bytes.

Entries	4
Compression	Deflate for text entries, stored for payload.bin
Encrypted	No
ZIP64	No
Largest entry	payload.bin, 20,967,670 bytes

First bytes of the file

The first 64 bytes of sample-zip-20mb.zip as a hex dump: offset, bytes, then the same bytes as text. The ZIP signature is 50 4B 03 04.

00000000  50 4b 03 04 14 00 00 00 08 00 00 00 21 5c 2a e6  |PK..........!\*.|
00000010  3b 63 6e 00 00 00 7b 00 00 00 0a 00 00 00 52 45  |;cn...{.......RE|
00000020  41 44 4d 45 2e 74 78 74 0a 4e cc 2d c8 49 0d 49  |ADME.txt.N.-.I.I|
00000030  2d 2e 71 cb cc 49 2d 56 28 06 f3 15 a2 3c 03 14  |-.q..I-V(....<..|

Preview

ZIP files cannot be shown in a browser. Download the file and open it in an application that reads ZIP, such as Windows Explorer, macOS Archive Utility, 7-Zip.

Where 20 MB matters

A 20,971,520-byte file: right at the default attachment limit of Outlook, and just under the 25 MB ceilings of Gmail and GitHub web uploads. These are the default limits a file of this size is useful for testing:

System	Limit	Note
Microsoft Outlook	20 MB of attachments by default for internet mail accounts	This file is right at the limit; add a second attachment and it is exceeded.
Gmail	25 MB per message	Under the limit, although email encoding adds about a third in transit.
GitHub web uploads	25 MiB per file added through the browser	Accepted. Pushing with Git allows larger files.
Cloudflare Pages assets	25 MiB per file	The largest round size that can be served as a static asset.
Amazon API Gateway	10 MB payload	Rejected; the upload has to go directly to object storage.
ASP.NET Core (Kestrel)	About 28.6 MB request body by default	Accepted with room for the multipart overhead.

All 20 MB sample files

Use this file for

Testing email attachment limits
Testing archive uploads and extraction
Checking limits on extracted size and entry count

Testing notes for ZIP

An archive can expand to far more than its own size. Enforce limits on total extracted bytes and entry count to guard against zip bombs.
Entry names may contain "../". Extracting without validating paths lets an archive write outside the target folder.

ZIP format reference

Technical details

File name	sample-zip-20mb.zip
Format	ZIP (ZIP archive)
Extension	.zip
MIME type	application/zip
Size	20,971,520 bytes (20 MB)
Kind	Binary
Signature	50 4B 03 04
SHA-256	05ec99adb50d2d23b4eeb5d677acab7ff37086435bfbd63e992a44ead7c36d42
Created	2026-10-14
Validation	Exact size, signature bytes and structure checked when the generator was built; your copy is checked against the SHA-256 after it is created
Preview	Not available for this file; details only
Source	Generated in your browser by this site's generator; not copied from elsewhere
Licence	Free to use, modify and redistribute (terms)
Category	Archives

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

Verify your copy

This file is created in your browser, so it has no direct URL for curl or wget. The bytes are the same every time and in every browser, so after saving it you can compare its checksum with the SHA-256 value above.

sha256sum sample-zip-20mb.zip     # Linux
shasum -a 256 sample-zip-20mb.zip # macOS

On Windows, run Get-FileHash sample-zip-20mb.zip -Algorithm SHA256 in PowerShell. For scripts and pipelines, save the file once and keep your own copy, or use a 1 MB file, which has a direct URL.

Related files

Questions about this file

Is this file exactly 20 MB?: Yes. It is 20,971,520 bytes, which is 20 MB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
What is inside the 20 MB ZIP file?: 4 entries: a README, a CSV file and a JSON file compressed with deflate, plus payload.bin, 20,968,261 pseudo-random bytes stored without compression so the archive is exactly 20,971,520 bytes.
What is inside the sample ZIP files?: A README, a small CSV file, a small JSON file and a payload.bin entry of pseudo-random bytes that sets the archive size. The smallest archives hold fewer entries.

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