The overlooked PDF problem in upload forms: fixed file-size limits

A small product detail I keep running into: upload forms often fail PDFs for a very boring reason.

The file is not broken. The layout is fine. The user just needs the PDF to be under a fixed limit like 10 MB, 20 MB, or 25 MB.

This happens a lot with:

• portfolio submissions
• school or job applications
• client handoff portals
• internal forms
• support ticket attachments

The usual advice is “compress the PDF,” but that is a bit vague. In practice, the user does not always want maximum compression. They want a specific outcome:

Make this PDF fit under the upload limit, then let me check whether it still looks acceptable.

That is the workflow I built TinyPDF around:

https://tinypdf.cn/?utm_source=devto&utm_medium=developer_promo&utm_campaign=portfolio_upload_limits&utm_content=devto_upload_limit_workflow_20260706

It is intentionally narrow:

1. Upload one PDF.
2. Enter the target size in MB.
3. Download the compressed result.
4. Open the result and inspect it before submitting.

The interesting product lesson for me is that “PDF compression” is too broad a category. The sharper use case is the moment when an upload form rejects a file and the user has one concrete number to hit.

If you build upload flows, what file-size limits do you usually set for PDFs? And do you explain the limit before or after the upload fails?