Gemini’s 1M token window may still struggle with long PDFs
Gemini says its 1 million token can understand up to about 1,500 pages of text or 30,000 lines of code. In a test with a 400-page book PDF, both Flash and Pro produced only one-sentence summaries for chapters later in the book when asked for a detailed chapter-by-chapter summary. Pro also showed a warning that the uploads might be too large for best results.
Even on the , uploading a very long file does not guarantee deep, even coverage of the whole document. The 1 million token claim appears to describe how much Gemini can take in, not a promise that every long-document task will produce complete, high-quality output.
Key points
- Gemini advertises a 1 million token for very long text or code.
- A 400-page PDF produced weak summaries for later chapters in both Flash and Pro.
- Pro warned that the uploads might be too large for best results.
- The did not remove the practical limit seen in this test.
- Long documents should be handled in smaller chunks when accuracy matters.