Download 7 MB PDF file for testing
Open the single page and check document-upload behavior. The preset is 7 MiB (7,340,032 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: 7,340,032 B. Generate and download each file to test your endpoint.
Where a 7 MB PDF comes up
- Testing whether outgoing mail from your app survives a self-hosted Postfix relay with factory settings.
- Measuring how attachment encoding changes a message size between your code and the mail server.
- Uploading a mid-size document to PHP endpoints that have raised upload_max_filesize but kept other defaults.
Limits it lands on
- Postfix rejects messages above message_size_limit, which defaults to 10,240,000 bytes. Base64 with standard line breaks makes this PDF about 10.04 million bytes, leaving under 200 KB for headers.
- It stays below PHP's default post_max_size of 8M, so a PHP server with only upload_max_filesize raised will still receive it.
What is inside the file
Padding accounts for 7,339,312 bytes; the readable part is the same single A4 page used across this site's PDFs.
Because the size is exact, comparing the received attachment byte-for-byte is a quick way to spot truncation.
Questions
Why test email with a 7 MB file?
It is the largest of these PDFs whose encoded form still fits a stock Postfix limit, so it separates "my server is default" from "my server was tuned".
Does base64 always add a third?
Close to it: every 3 bytes become 4 characters, plus line breaks, so attachments grow by roughly 33–37%.
Reference and checks
Format reference: PDF 32000-1.
Preset target: 7 MiB (7,340,032 bytes). Verify the downloaded file's byte count.
Generate another size in this format · Technical notes for every format · Guide to testing file upload limits · Data processing and privacy
Related tools: Merge PDF · Compress PDF.
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