Documents · HTML
A 25 MB HTML file, on demand.
Exactly 26,214,400 bytes of a complete HTML5 document that renders in a browser, built on your machine the moment you press the button.
26,214,400 bytes, exactly.
Every byte above the 189 bytes structural minimum goes into an HTML comment, which is why this file still behaves like one a real user would send.
Unit convention
25 MB on this page means exactly 26,214,400 bytes, using the binary (MiB) convention some systems label "MB" for short. 1 MB in the strict decimal sense is 1,000,000 bytes; 1 MiB is 1,048,576 bytes — the readout above always shows the exact count either way.
Approximate size equivalents
Roughly 14,564 pages of typed text, 27 minutes of 128 kbps audio, 2 minutes of CD-quality audio, 10 photos from a 12 MP camera. These figures compare file size only — the generated file does not contain this text, audio or image content.
Accepted by
Gmail attachment, Cloudflare Free proxy body, GitHub repository file — all publish a limit at or above this size, based on commonly cited figures that can vary by plan and change over time.
Rejected by
Outlook.com attachment, Discord free attachment, AWS API Gateway payload — this exceeds their commonly cited limit, which makes it a useful negative test. Published limits can vary by plan and change over time.
Other HTML sizes
Mail servers and chat apps draw the line in this band — Gmail attachments stop at 25 MB, and plenty of APIs cap request bodies alongside them.
Questions.
Is this 25 MB HTML file valid?
Yes. It is a complete HTML5 document that renders in a browser. The extra bytes sit in an HTML comment, so it opens in Chrome, Firefox, Safari and Edge.
Does 25 MB mean 26,214,400 bytes?
On this page, yes — 25 MB uses the binary (MiB) convention, so the file is exactly 26,214,400 bytes. 1 MB in the strict decimal sense would be a different, smaller byte count. Upload validators may use either convention, so the exact byte count is always shown to remove any ambiguity.
What is a 25 MB file used for?
Mail servers and chat apps draw the line in this band — Gmail attachments stop at 25 MB, and plenty of APIs cap request bodies alongside them. For HTML specifically, the usual job is testing page-weight budgets and HTML upload handling.
Where is the file downloaded from?
Nowhere. It is assembled in a Web Worker on your own device and handed to the browser as a Blob, so nothing is uploaded, fetched or stored.