Download 20 MB DOCX file for testing
Use the Word-format fixture to test a document-upload limit. The preset is 20 MiB (20,971,520 bytes); choose MB for decimal megabytes.
1 MB = 1,000,000 B · 1 MiB = 1,048,576 B
Advanced: test an upload limit
Enter the byte limit above, then choose one byte below, the exact limit or one byte above. Each choice uses the same base: 20,971,520 B. Generate and download each file to test your endpoint.
What to test with this DOCX fixture
- Validate the ZIP/XML structure and reader behavior separately from the byte limit. A 20 MiB file can exceed a decimal 20 MB cap before multipart or email encoding overhead.
- Testing document management systems with a large .docx attachment.
- Comparing attachment validation with the full encoded email-message limit.
- Verifying antivirus and DLP scanners finish within your upload timeout.
Limits it lands on
- The legacy 20 MB label here means 20 MiB (20,971,520 bytes); a decimal 20 MB cap is 20,000,000 bytes. Choose decimal MB in the generator to test that cap.
- A raw attachment and an email message have different sizes. Base64 encoding adds roughly one third before headers and line breaks, so a nominal 20 MB message limit does not guarantee that this attachment fits.
- Check the current client, account and server limits rather than assuming that Outlook, iCloud or a bot API accepts this file.
What is inside the file
The ZIP package contains [Content_Types].xml, relationships, word/document.xml with two paragraphs and a binary part declared in the content types. The binary part holds the padding.
Because the padding is stored uncompressed inside the package, the file stays exactly 20 MB after download.
Questions
Does the document contain 20 MB of text?
No. document.xml contains two short paragraphs; a binary part supplies the rest of the package size.
Does it fit in a 20 MB email?
Not necessarily. The client attachment limit and the total encoded message limit are separate. Test the actual mail system with its current limits.
Is desktop application compatibility guaranteed?
No. Package structure and exact bytes can be validated separately; test opening and re-saving in the applications used by your workflow.
Does 20 MB on this page mean 20000000 bytes?
This legacy URL selects 20 MiB: 20,971,520 bytes. A decimal 20 MB cap is 20,000,000 bytes. Select decimal MB or enter exact bytes on the DOCX format page.
Reference and checks
Format reference: ECMA-376.
Measured regression fixture (2026-10-13): 20,971,520 bytes. Validation method and limits.
Generate another size in this format · Technical notes for every format · Guide to testing file upload limits · Data processing and privacy
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