ChatGPT says your file is too large. Which of the 4 caps did you hit?

The four ceilings

The bottom row is the one that catches almost everyone, and it is not a size limit at all.

Working out which one you hit

1. Check the actual file size

   Right-click, then Get Info or Properties. Write the number down.

2. Is it over 512 MB?

   Almost certainly not. If it is, you hit the size ceiling and compressing will fix it.

3. Is it a spreadsheet over 50 MB?

   Different ceiling, lower. Exporting to CSV usually drops it sharply, since XLSX carries formatting that CSV does not.

4. Under 10 MB and it still refused?

   Then it is length. There is no amount of compression that helps, because the words are the problem.

If it is genuinely a size problem

Nearly always images inside a document.

Here is the useful part: every ChatGPT plan except Enterprise discards images from documents anyway. It extracts the digital text and throws the pictures away. So compressing the images, or stripping them entirely, costs you nothing that ChatGPT was ever going to read.

• PDF: use any compress or reduce-size option, or export to plain text.
• Word: Save As, then reduce image size, or export to plain text.
• Spreadsheet: save as CSV. Formatting and formulas go, data stays.

If it is a length problem

The common case, and compression is not the answer to any part of it.

A three-hundred-page report can be a couple of megabytes and be far past 2 million tokens. The only fix is to send less at a time.

Send the section you need. You rarely need three hundred pages read. Pull out the chapter your question concerns.

Split it and send the parts in order. Cut it into pieces small enough to go through, then send them one after another with an instruction first:

I am sending a long document in several parts. Do not answer until I tell you the last one has arrived. Reply "received" after each.

Without that instruction ChatGPT answers part one as though it were the whole thing.

The version of this problem with no error at all

Worth knowing, because it is more dangerous than the message you got.

Sometimes a long document is not rejected. It uploads, and ChatGPT reads as much as fits and works from that, silently. You get a confident summary of the first portion with nothing to suggest anything is missing.

At least "the file is too large" tells you something went wrong. Check for the silent version by asking something only answerable from the end:

What is the final section called?

If it cannot say, it never read that far.

What does not work