How to use fewer tokens when you give documents to ChatGPT or Claude

If you regularly attach documents to ChatGPT, Claude or Gemini, you've probably hit a usage limit sooner than you expected. Documents are often the biggest thing in a conversation, and the way you attach them makes a large difference to how much of your allowance they use.

Why documents are expensive

AI assistants measure everything in tokens: small pieces of text, roughly four characters of English each. Your usage limit, the model's memory of the conversation and, on paid APIs, the bill are all counted in tokens.

Three things make documents costly:

• PDFs can be read as images as well as text. Some assistants look at each PDF page as a picture so they can understand charts and layout. That's useful for a brochure, but for a ten-page agreement it means paying for ten images on top of the words.
• Formatting and clutter come along for the ride. Page headers, footers, page numbers, empty spreadsheet cells and hidden sheets are all read and counted.
• Every message re-reads the conversation. The document you attached in your first message is counted again each time you ask a follow-up, for as long as the chat continues.

1. Convert to plain text or Markdown first

Plain text carries the same words with none of the overhead. Markdown is plain text with a light structure (headings, lists and tables written with simple symbols), which AI models read very well.

A typed PDF of a few megabytes often becomes a few kilobytes of Markdown. You keep every word, and the assistant no longer has to process page images.

2. Send only the part you need

If your question is about clause 14, you don't need to send the whole 60-page contract. After converting, delete what you don't need and paste only the relevant section. This is the biggest saving of all, and it also tends to give better answers, because the model isn't distracted by unrelated text.

3. Trim spreadsheets before you send them

Spreadsheets are deceptively expensive. Before converting:

• Delete empty rows and columns, and sheets you don't need.
• Remove columns that aren't relevant to your question.
• For large tables, send a summary or a filtered view rather than every row.

Docuflat converts each sheet to a Markdown table and drops completely empty rows and columns automatically. See Excel to Markdown tables for more.

4. Start a new chat for a new topic

Because each message re-reads the whole conversation, a long chat with a large attachment gets more expensive with every reply. When you move on to a different question, start a fresh chat and paste only what that question needs.

5. Keep a converted copy of documents you use often

If you refer to the same policy, price list or contract every week, convert it once and keep the Markdown file. Many assistants also let you store reference files in a project or workspace, which avoids attaching them again and again.

When to keep the original PDF

Plain text loses some things. Keep the original file when the layout itself matters:

• Signatures, stamps and seals you need the assistant to notice
• Charts, diagrams and photos
• Forms where the position of a box carries meaning

For everything else, such as contracts, reports, notices, statements and correspondence, converting first is almost always the better choice.