How to Upload Knowledge into Your Custom GPT

Your step-by-step guide to making a smarter GPT with your own documents.

Why Upload Your Own Knowledge?

Even the best GPT won’t really sound like you — or know your stuff — unless you teach it. That’s where knowledge uploads come in.

By uploading files (PDFs, DOCs, TXT, etc.), your GPT can:

• Answer questions based on your business material
• Speak in your tone and style
• Cut down on repetitive manual responses
• Act as a trained assistant, contract reviewer, customer explainer, or internal helpdesk

Think of it as giving your GPT “homework.” You hand it your documents, and it quietly studies them behind the scenes so it can sound smart in front of your users.

Why Upload Your Own Knowledge?

Even the best GPT won’t truly sound like you — or know your stuff — unless you teach it. That’s where knowledge uploads come in.

By uploading files (PDFs, DOCs, TXT, etc.), your GPT can:

• Answer questions based on your business material
• Speak in your tone and style
• Cut down on repetitive manual responses
• Act as a trained assistant, contract reviewer, customer explainer, or internal helpdesk

Think of it as giving your GPT “homework.” You hand it your documents, and it quietly studies them behind the scenes so it can sound smart in front of your users.

Step-by-Step: How to Upload Documents to a Custom GPT

Prerequisite: You’ve already created your Custom GPT (via https://chat.openai.com/gpts). You’re now ready to add your own knowledge base by uploading documents.

Step 1: Go to the GPT Builder
Go to https://chat.openai.com/gpts. Click on your Custom GPT and select “Edit GPT.”

Step 2: Find the “Knowledge” Section
In the left-hand menu, select “Knowledge” and click “Upload files.”

Step 3: Add Your Files
Drag and drop or browse to upload your documents. Supported formats include .pdf, .docx, .txt, .md, .csv. You can upload up to 20 files with a combined size of 512 MB. You can ask ChatGPT to help you assess and convert documents into these formats if you need to with this prompt:

I want to use this document inside a Custom GPT as part of its Knowledge section. Please assess the content and do the following:

Identify if this content is suitable to be uploaded directly (e.g. clear, clean, complete), or if it needs to be rewritten, summarised, or broken into smaller chunks.

If the formatting is poor (e.g. tables, layout issues, scanned PDF style), convert it into clean, text-based markdown or plain text format that preserves all meaning and structure.

Remove any unnecessary elements such as headers/footers, page numbers, duplicated content, or visual formatting that won’t translate well into plain text.

Structure the output into a clean, well-labelled text file that can be uploaded into the Knowledge section of a Custom GPT (i.e. .txt or .md format). Use clear section titles and bullet points where appropriate.

Keep all the important content, but make sure it’s optimised for retrieval by a GPT model. That means using simple, clear language and logical structure.

Name the output file appropriately (e.g. “2025_PricingOverview.txt” or “Legal_Terms_Guide.md”).

Please begin by assessing the suitability of the input and then output a clean, upload-ready version.

[Optional Tip (if you’re uploading a file):
Start with:]
“Please assess the uploaded file using the instructions below…” and paste the prompt afterward.

Step 4: Check the File List
You’ll see a list of your uploaded files. Use the trash icon to remove any if needed. You can update this list at any time.

Step 5: Save and Publish
Click “Save” or “Publish” to apply your changes. Your GPT can now access your uploaded documents to answer relevant prompts.

What Kind of Files Work Best?

Ideal Files:

• Cleanly written PDFs (guides, SOPs, FAQs)
• Contracts and legal templates
• Onboarding documents, pricing sheets
• Internal wikis (exported to .txt or .md)

Avoid These:

• Scanned documents with images
• Slides with only images or no speaker notes
• Encrypted or locked PDFs
• Files full of links without explanations

Tip: For web pages, copy-paste the content into a clean .txt or .md file.

How the GPT Uses This Info
Your GPT will search the uploaded documents in real time when a relevant prompt is given. It doesn’t memorise the content — it retrieves from it. It performs best when the material is clearly written and structured.

Watch Outs

1. No File Structuring = Confused GPT
   If you upload a single giant PDF with 50 topics and poor formatting, the GPT will struggle. Break it into smaller, well-labelled files.
2. Bad Formatting = Bad Responses
   If your file has unusual fonts, broken tables, or visual layouts (especially common in PDFs), the GPT may misread it. Clean formats like .txt, .docx, or markdown work best.
3. No Source Citations
   By default, GPT won’t say where the information came from. If this matters, add an instruction like: “Always mention which document you’re referencing.”
4. File Limit
   You can only upload 20 files per GPT. Curate carefully and consider trimming or combining related documents.

Curating the “Core Knowledge” for Best Results

Ask yourself:

1. What do I want this GPT to do? Only upload documents relevant to those tasks.
2. Will someone else use this? Include glossaries or context if needed.
3. Is this content clear and self-contained? If not, simplify or split into manageable chunks.

Example Use Cases:
LegalGPT: Upload contracts, clause trackers, fallback templates
SalesGPT: Upload pitch decks, product specs, objection-handling guides
HRGPT: Upload company policies, onboarding FAQs

Bonus Tip: Pair With System Instructions

After uploading, adjust your GPT’s instructions to reflect how it should use that knowledge. Example: “You are a helpful assistant trained specifically on SQREEM’s legal contracts and internal SOPs. Always answer using information from the uploaded documents. If unsure, say ‘I’m not certain — please check with legal.’” You can also use the “Prompt Starter” section to load reusable queries.

Updating Your Knowledge Files Later

Return to “Edit GPT > Knowledge” anytime to remove outdated files or upload new ones. Save to apply changes. Your GPT will instantly use the latest content.

Version Control and Multiple GPTs

You can create multiple GPTs with different document sets, or use file naming conventions to stay organised. Examples:
01_PricingOverview_Q1-2025.txt
02_TOS_Updated_April2025.docx
03_FAQ_InternalOnly.md

What To Do Next

Now that your GPT has your content, test it by asking:
“Summarise our latest pricing model”
“What’s our refund policy?”
“Write a client email using our onboarding flow”
“Check clause 7.3 in the uploaded SOW template”

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