You want to compare twenty-five scanned reports in one conversation. Each is a 40MB PDF of about 300 pages. What should you expect?

The principle — several separate limits apply at once, and predicting an upload means checking each rather than the one you happen to remember.

Why the key is correct — a chat accepts up to twenty files. Twenty-five reports breaches that cap even though every other rule is satisfied: each file is 40MB against a 500MB allowance, and 300 pages against a thousand-page ceiling. Splitting the set across conversations, or narrowing to the reports that matter, is what makes the task fit.

Why the others are wrong — size is not the only rule in play. 40MB is nowhere near the per-file ceiling. And 300 pages is comfortably inside what PDFs allow.

Splitting the set also tends to improve the answer, because a comparison across five reports is a sharper question than one across twenty-five.

Remember this — count, size and page length are three separate ceilings. Check the one your task is closest to.

Sources — Anthropic's file upload documentation.