The Complete Guide to ChatGPT’s Models: Understanding GPT-4o, GPT-4-turbo, and GPT-3.5
As of July 2025
If you’re using ChatGPT and wondering which model does what, this post breaks down every available model from OpenAI as of July 2025. Whether you’re a casual user, a business leader, a content creator, or a developer, understanding the differences can help you get the most from the platform.
ChatGPT Model Lineup
There are currently three core models powering ChatGPT:
GPT-4o (Omni)
GPT-4-turbo
GPT-3.5-turbo
Each serves a different purpose depending on your use case, budget, and access tier.
GPT-4o (Omni)
GPT-4o is OpenAI’s most advanced and capable model. It’s designed to be multimodal, which means it can process text, images, and audio—and even respond in real-time using voice if you’re a Pro user. GPT-4o is faster, more responsive, and less expensive to run than GPT-4-turbo, and it comes with highly nuanced emotional and conversational understanding.
Key Features:
Accepts text, image, and audio input
Responds via text, images, or real-time voice (voice in Pro only)
Advanced image understanding and reasoning
Powers the default ChatGPT experience for Free and Pro users
Persistent memory and custom instructions for Pro users
Extremely fast and accurate
GPT-4-turbo
GPT-4-turbo is a high-performance variant of GPT-4 optimized for cost and speed. It handles both text and image inputs and is available to Plus users for $20/month. While not quite as sophisticated as GPT-4o, it remains a powerful tool for writing, research, brainstorming, coding, and sales enablement tasks.
Key Features:
Text and image input
No voice capabilities
Up to 128,000 token context window
Custom instructions and memory available for Pro users
Great for long-form content and structured prompts
GPT-3.5-turbo
GPT-3.5-turbo is the model powering ChatGPT’s free tier. It’s text-only and best for casual use, basic copywriting, short answers, and brainstorming. It’s fast and lightweight, but it lacks the depth, accuracy, and multimodal capabilities of the GPT-4 series.
Key Features:
Text-only input
Available to all free ChatGPT users
16,000 token context window
No access to memory or advanced tools
ChatGPT Model Feature Comparison
1. Text Input
GPT-4o: Yes
GPT-4-turbo: Yes
GPT-3.5-turbo: Yes
2. Image Input
GPT-4o: Yes
GPT-4-turbo: Yes
GPT-3.5-turbo: No
3. Audio/Voice Input
GPT-4o: Yes (Pro only)
GPT-4-turbo: No
GPT-3.5-turbo: No
4. Real-Time Conversation
GPT-4o: Yes (Pro only)
GPT-4-turbo: No
GPT-3.5-turbo: No
5. Max Context Window
GPT-4o: ~128K tokens
GPT-4-turbo: ~128K tokens
GPT-3.5-turbo: 16K tokens
6. Memory (ChatGPT only)
GPT-4o: Yes
GPT-4-turbo: Yes
GPT-3.5-turbo: No
7. Speed
GPT-4o: Fastest
GPT-4-turbo: Fast
GPT-3.5-turbo: Fast
8. Accuracy
GPT-4o: Highest
GPT-4-turbo: High
GPT-3.5-turbo: Moderate
ChatGPT Access Tiers and Pricing
Plan:
Free • Monthly Cost: $0 • Default Model: GPT-3.5-turbo
Plus • Monthly Cost: $20 • Default Model: GPT-4-turbo
Pro • Monthly Cost: Varies • Default Model: GPT-4o with full access
Feature:
Text input • GPT-4o: Yes • GPT-4-turbo: Yes • GPT-3.5-turbo: Yes
Image input • GPT-4o: Yes • GPT-4-turbo: Yes • GPT-3.5-turbo: No
Audio/Voice input • GPT-4o: Yes (Pro only) • GPT-4-turbo: No • GPT-3.5-turbo: No
Real-time conversation • GPT-4o: Yes (Pro only) • GPT-4-turbo: No • GPT-3.5-turbo: No
Max context window • GPT-4o: ~128K tokens • GPT-4-turbo: ~128K tokens • GPT-3.5-turbo: 16K tokens
Memory (ChatGPT only) • GPT-4o: Yes • GPT-4-turbo: Yes • GPT-3.5-turbo: No
Speed • GPT-4o: Fastest • GPT-4-turbo: Fast • GPT-3.5-turbo: Fast
Accuracy • GPT-4o: Highest • GPT-4-turbo: High • GPT-3.5-turbo: Moderate
ChatGPT Access Tiers and Pricing
Plan:
Free • Monthly Cost: $0 • Default Model: GPT-3.5-turbo
Plus • Monthly Cost: $20 • Default Model: GPT-4-turbo
Pro • Monthly Cost: Varies • Default Model: GPT-4o with full access
Special Use Cases by Model
Voice conversations: GPT-4o (Pro tier)
Advanced image analysis: GPT-4o and GPT-4-turbo
PDF/file uploads: GPT-4o (Pro users can upload files)
Coding and technical writing: GPT-4o and GPT-4-turbo
Marketing content: All models, but GPT-4o performs best
Document summarization: GPT-4o with large token context excels
Customer support bots and training data analysis: GPT-4-turbo via API is the cost-effective choice
Memory and Customization
Pro users using GPT-4-turbo or GPT-4o have access to memory and custom instructions. Memory allows ChatGPT to remember your preferences, brand tone, and past conversations. Custom instructions let you fine-tune the AI’s behavior and responses.
GPT-3.5 does not support memory or any advanced tools.
GPT-4o is the most versatile and capable model to date. If you rely on ChatGPT for professional work, content development, business strategy, or real-time interaction, it’s worth exploring the Pro plan for full GPT-4o access.
For everyday tasks, GPT-3.5 and GPT-4-turbo continue to be strong options based on your budget and use case.