20 MB PNG sample

A PNG file of exactly 20,971,520 bytes. It is a valid Portable Network Graphics file, generated by this site. Compare its checksum and test it with the parser used by your application. Use it wherever you need a 20 MB sample, test or dummy PNG file.

sample-png-20mb.png

20 MB20,971,520 bytes

Download 20 MB PNG

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

Type: image/png
SHA-256: 917213bf02302ab03c63cdc64da23fb81b860206ebdbc0c27fd40c02723f2e76
Delivery: Created in your browser from static generator assets (how it works).

What is in this file

A 3072 × 2275 test card. The pixel data sits in a deflate stream made of stored blocks, so the size is set by the pixel count. 234 bytes of tEXt comment chunk bring the file to the exact size.

Dimensions	3,072 × 2,275 px
Colour type	Truecolour RGB, 8 bits per channel
Transparency	No
Compression	Deflate stream of stored blocks
Interlaced	No

First bytes of the file

The first 64 bytes of sample-png-20mb.png as a hex dump: offset, bytes, then the same bytes as text. The PNG signature is 89 50 4E 47 0D 0A 1A 0A.

00000000  89 50 4e 47 0d 0a 1a 0a  00 00 00 0d 49 48 44 52 |.PNG........IHDR|
00000010  00 00 0c 00 00 00 08 e3  08 02 00 00 00 1d cc 5e |...............^|
00000020  c9 00 00 00 de 74 45 58  74 43 6f 6d 6d 65 6e 74 |.....tEXtComment|
00000030  00 53 61 6d 70 6c 65 54  65 73 74 46 69 6c 65 73 |.SampleTestFiles|

Preview

Creates the file in your browser and shows it here. Nothing large is downloaded from our server.

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

Measuring download speed from your own server or CDN
Verifying dimension limits
Testing image uploads that must stay lossless

Testing notes for PNG

Every chunk carries a CRC, so a strict decoder rejects a file that was altered in transit.
PNG compresses flat colour extremely well, so a tiny file can expand to a very large bitmap. Check dimensions before decoding.

PNG format reference

Technical details

File name	sample-png-20mb.png
Format	PNG (Portable Network Graphics)
Extension	.png
MIME type	image/png
Size	20,971,520 bytes (20 MB)
Kind	Binary
Signature	89 50 4E 47 0D 0A 1A 0A
SHA-256	917213bf02302ab03c63cdc64da23fb81b860206ebdbc0c27fd40c02723f2e76
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	Images

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-png-20mb.png     # Linux
shasum -a 256 sample-png-20mb.png # macOS

On Windows, run Get-FileHash sample-png-20mb.png -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 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 PNG file?: A 3072 × 2275 test card. The pixel data sits in a deflate stream made of stored blocks, so the size is set by the pixel count. 234 bytes of tEXt comment chunk bring the file to the exact size.
Is there a sample with transparency?: Yes. The curated library includes a 512 × 512 PNG with an alpha gradient.

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