10 MB CSS sample

A CSS file of exactly 10,485,760 bytes. It is a valid Cascading Style Sheets file, generated by this site. Compare its checksum and test it with the parser used by your application. Use it wherever you need a 10 MB sample, test or dummy CSS file.

sample-css-10mb.css

10 MB10,485,760 bytes

Download 10 MB CSS

Created in your browser in a few seconds, then checked against the SHA-256 checksum. The file is not uploaded anywhere. No sign-up.

Type: text/css
SHA-256: 47863c68d9785dc14cc40c8fb58eaa7385c12aa3ff2cbdce22e1918c1084d222
Delivery: Created in your browser from static generator assets (how it works).

What is in this file

A custom property block, a body rule and 105,614 class rules with colours, margins, padding and border radii. A comment at the end brings the file to the exact size.

Rules	105,616
Custom properties	2
Imports	None
Encoding	UTF-8 (ASCII characters only)

How the file begins

The opening lines of sample-css-10mb.css, exactly as they appear in the file.

00000000  2f 2a 20 53 61 6d 70 6c  65 54 65 73 74 46 69 6c |/* SampleTestFil|
00000010  65 73 20 73 61 6d 70 6c  65 20 43 53 53 20 66 69 |es sample CSS fi|
00000020  6c 65 20 28 31 30 20 4d  42 29 20 2a 2f 0a 3a 72 |le (10 MB) */.:r|
00000030  6f 6f 74 20 7b 0a 20 20  2d 2d 69 6e 6b 3a 20 23 |oot {.  --ink: #|

Preview

Creates the file in your browser and shows the first 64 KB of it.

Where 10 MB matters

A 10,485,760-byte file: over the default limits of PHP, API Gateway and Spring Boot requests. These are the default limits a file of this size is useful for testing:

System	Limit	Note
Amazon API Gateway	10 MB payload	A 10 MB file in a multipart or base64 body is over the limit.
Spring Boot multipart	10 MB per request by default (max-request-size)	Exceeded once form overhead is added.
PHP	8 MB POST body by default (post_max_size)	Rejected before the script runs.
Amazon S3 multipart upload	5 MiB minimum part size	This file splits into exactly two minimum-sized parts.
Email attachments	Commonly 20 to 25 MB per message	10 MB fits, at about 13.3 MB once encoded.

All 10 MB sample files

Use this file for

Finding the first upload limit in a new stack
Testing code editors and syntax highlighters
Testing minifiers and bundlers

Testing notes for CSS

With X-Content-Type-Options: nosniff, browsers refuse a stylesheet that is not served as text/css.

CSS format reference

Technical details

File name	sample-css-10mb.css
Format	CSS (Cascading Style Sheets)
Extension	.css
MIME type	text/css
Size	10,485,760 bytes (10 MB)
Kind	Text
SHA-256	47863c68d9785dc14cc40c8fb58eaa7385c12aa3ff2cbdce22e1918c1084d222
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	Code

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-css-10mb.css     # Linux
shasum -a 256 sample-css-10mb.css # macOS

On Windows, run Get-FileHash sample-css-10mb.css -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 10 MB?: Yes. It is 10,485,760 bytes, which is 10 MB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
What is inside the 10 MB CSS file?: A custom property block, a body rule and 105,614 class rules with colours, margins, padding and border radii. A comment at the end brings the file to the exact size.
What do the sample stylesheets contain?: Custom properties, a body rule and a long list of class rules, with no @import rules or external URLs.

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