How to Fine-Tune GPT-3.5-Turbo: Unlocking the Power of Customization

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How to Fine-Tune GPT-3.5-Turbo: Unlocking the Power of Customization

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In the world of artificial intelligence, OpenAI's GPT-3.5-turbo stands as a remarkable achievement, pushing the boundaries of what machines can do with natural language. This powerful language model is capable of generating human-like text, answering questions, and even carrying on coherent conversations. However, as impressive as GPT-3.5-turbo is in its vanilla form, there are times when you might need it to be more tailored to a specific task or domain. This is where fine-tuning comes into play.

Fine-tuning GPT-3.5-turbo allows you to take this already extraordinary language model and mold it to suit your particular needs. Whether you want it to generate code, write essays, or provide personalized responses in a chatbot, fine-tuning enables you to customize GPT-3.5-turbo for your unique application. In this article, we'll delve into the intricacies of fine-tuning GPT-3.5-turbo, exploring the steps involved, its effectiveness, and some common questions regarding the process.

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How do I fine-tune my GPT-3.5-turbo?

Fine-tuning GPT-3.5-turbo involves a series of steps that we've outlined above. However, let's delve into a bit more detail on how you can go about fine-tuning your GPT-3.5-turbo model once you have access to the OpenAI API and your training data is ready.

  1. Define Your Objective: Clearly define the specific task or domain for which you want to fine-tune GPT-3.5-turbo. Whether it's generating medical diagnoses, writing code in a particular programming language, or providing legal advice, a well-defined objective is crucial.
  2. Curate High-Quality Data: As mentioned earlier, gather a diverse and comprehensive dataset that represents the task or domain. Ensure that the data is relevant and well-structured. Clean, well-labeled data is essential for effective fine-tuning.
  3. Prepare Data for Upload: Organize your data into a format that can be uploaded to the OpenAI platform. Depending on your dataset's size, you may need to split it into manageable batches.
  4. Fine-Tuning Configuration: Configure the fine-tuning parameters, including the number of training steps, batch size, and learning rate. These settings can be adjusted based on the complexity of your task and available computing resources.
  5. Initiate Fine-Tuning: Start the fine-tuning process on the OpenAI platform. During this phase, the model learns from your data and adapts to your specific requirements. Monitor its progress and performance on validation data.
  6. Iterate and Optimize: Fine-tuning is an iterative process. You may need to fine-tune multiple times, adjusting parameters, and re-evaluating the model's performance until you achieve the desired results.
  7. Save the Model: Once you are satisfied with your fine-tuned model's performance, save it for future use. You can now integrate it into your applications or services to provide tailored responses.

Can GPT-3.5 Turbo be fine-tuned?

As of my last knowledge update in January 2022, fine-tuning was primarily available for the base GPT-3.5-turbo models. GPT-3.5-turbo, being a variant of GPT-3, may not have the same fine-tuning capabilities. However, OpenAI regularly updates its offerings, so it's essential to check OpenAI's official documentation or announcements for the most up-to-date information regarding fine-tuning options for specific models.

Is it Possible to Fine-Tune ChatGPT?

Fine-tuning has been primarily associated with GPT-3.5-turbo, and ChatGPT is based on the GPT-3.5-turbo architecture. Therefore, as of my last knowledge update, fine-tuning ChatGPT was not a widely available option. However, OpenAI's offerings and capabilities may evolve over time, so it's advisable to refer to OpenAI's official documentation or announcements for the latest information on fine-tuning options for ChatGPT or any other specific models.

How much data is needed to fine-tune GPT-3.5-turbo?

The amount of data needed to effectively fine-tune GPT-3.5-turbo can vary depending on several factors:

  1. Complexity of the Task: More complex tasks often require larger and more diverse datasets. Simple tasks may be fine-tuned effectively with a smaller amount of data.
  2. Quality of Data: High-quality, well-labeled data is crucial for successful fine-tuning. Noisy or low-quality data may require a larger dataset to compensate.
  3. Domain Specificity: If your task or domain is highly specialized, you may need a more extensive dataset to capture the nuances of that domain adequately.
  4. Model Size: The specific GPT-3.5-turbo variant you are using can impact the amount of data required. Larger models may need more data for effective fine-tuning.
  5. Available Resources: Your available computational resources and fine-tuning infrastructure can influence the size of the dataset you can effectively use.

In general, it's advisable to start with a reasonably sized dataset and monitor the fine-tuning process. If the model's performance is not meeting your expectations, you can consider adding more data incrementally until you achieve the desired results. Fine-tuning is an iterative process, and finding the right balance of data and model parameters is key to its success.

How to Fine-Tune a GPT-3.5-turbo Model: A Step-by-Step Guide

In this guide, we will walk through the process of fine-tuning a GPT-3.5-turbo model using Python. Fine-tuning allows you to customize the model for specific tasks or domains, enhancing its performance and relevance. We will cover everything from obtaining your API key to testing the fine-tuned model on new prompts.


Before we begin, make sure you have the following prerequisites in place:

  • An OpenAI account with access to the GPT-3.5-turbo API.
  • Python installed on your system.
  • The openai Python library installed (pip install openai).

Step 1: Get OpenAI API Key

To start, obtain your OpenAI API key by following these steps:

  1. Go to
  2. Log in to your OpenAI account.
  3. Click on your avatar and select "View API keys."
  4. Create a new secret key and save it for future use.

Sample Code to Get API Key:

# Replace 'YOUR_OPENAI_API_KEY' with your actual API key

Step 2: Create Training Data

Next, you need to prepare your training data. This data will teach the GPT-3.5-turbo model what responses you expect for specific prompts. The data should be in a JSONL format, with prompts and ideal responses.

Sample Code to Create Training Data:

import json

# Define your training data
training_data = [
    {"prompt": "Where is the billing ->", "completion": "You find the billing in the left-hand side menu."},
    {"prompt": "How do I upgrade my account ->", "completion": "Visit your user settings, then click 'upgrade account' button at the top."}

# Convert the data to JSONL format
file_name = "training_data.jsonl"
with open(file_name, "w") as output_file:
    for entry in training_data:
        json.dump(entry, output_file)

Step 3: Check the Training Data

You can use OpenAI's CLI data preparation tool to check your training data and get suggestions for improvements.

Run the following command in a Jupyter notebook or terminal:

!openai tools fine_tunes.prepare_data -f training_data.jsonl

Review the suggestions provided to ensure your training data is well-structured and effective.

Step 4: Upload Training Data

Now, upload your training data to OpenAI for fine-tuning:

Sample Code to Upload Training Data:

import openai

# Upload the training data
upload_response = openai.File.create(
    file=open(file_name, "rb"),
file_id =

Step 5: Fine-Tune Model

Fine-tune your GPT-3 model using the uploaded training data:

Sample Code to Fine-Tune Model:

# Start the fine-tuning process
fine_tune_response = openai.FineTune.create(training_file=file_id)

You can specify the model you want to fine-tune (e.g., "davinci") by providing the model parameter.

Step 6: Check Fine-Tuning Progress

Monitor the progress of your fine-tuning process using the following options:

Option 1: List Events

fine_tune_events = openai.FineTune.list_events(

Option 2: Retrieve Fine-Tuning Job

retrieve_response = openai.FineTune.retrieve(

Step 7: Save Fine-Tuned Model

Once the fine-tuning is complete, save the fine-tuned model for future use:

Sample Code to Save Fine-Tuned Model:

# Retrieve the fine-tuned model
fine_tuned_model = retrieve_response.fine_tuned_model

# Now you have a fine-tuned GPT-3 model ready for use

Step 8: Test the New Model on a New Prompt

Finally, test your fine-tuned GPT-3.5-turbo model on a new prompt:

Sample Code to Test the Model:

# Create a new prompt
new_prompt = "How do I find my billing ->"

# Run the completion with your fine-tuned model
answer = openai.Completion.create(

# Get the model's response
response_text = answer['choices'][0]['text']

Congratulations! You have successfully fine-tuned a GPT-3.5-turbo model and tested it on a new prompt.

Feel free to expand your training data, explore different fine-tuning approaches, and apply this knowledge to your specific use cases to maximize the potential of customized AI models.


Photo by Fotis Fotopoulos / Unsplash

Fine-tuning a GPT-3.5-turbo model is a transformative journey that empowers you to harness the full potential of artificial intelligence for your specific tasks and domains. In this comprehensive guide, we've covered the essential steps to fine-tune your GPT-3.5-turbo model, from obtaining your API key to testing the fine-tuned model on fresh prompts. With this knowledge at your disposal, you can embark on your fine-tuning adventure with confidence.

As you dive into the world of fine-tuning, remember the critical factors that influence success:

Complexity of the Task: Tailor your dataset size to the complexity of your task, opting for larger datasets for intricate tasks and smaller ones for simpler ones.

Quality of Data: Ensure your training data is of the highest quality, well-labeled, and free from noise or errors to yield optimal results.

Domain Specificity: Acknowledge the specificity of your domain and gather data that captures the nuances of that domain effectively.

Model Size: Consider the model size when selecting your dataset, as larger models may benefit from more extensive datasets.

Available Resources: Leverage your available computational resources and infrastructure to fine-tune efficiently within your constraints.

With these considerations in mind and the provided sample code, you can fine-tune your GPT-3.5-turbo model for a multitude of applications, from chatbots that offer impeccable customer support to code generators that simplify complex programming tasks.

The journey of customization doesn't end here; it's an ongoing process of optimization, expansion, and exploration. As you fine-tune your models, consider experimenting with different approaches, expanding your training data, and adapting to the evolving landscape of artificial intelligence.

The power of fine-tuning extends beyond GPT-3.5-turbo; it is a gateway to unleashing AI's potential to solve complex problems, assist in decision-making, and create innovative solutions. As you venture forth into this exciting realm, may your fine-tuned models unlock new horizons of possibilities and elevate the impact of artificial intelligence in your projects.

Happy fine-tuning!

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