GPT Models: A Guide to the Major OpenAI Models

There’s no shortage of AI models out there, but OpenAI’s GPT series stands out.

It’s not just one model. It’s a family of models, each with different strengths.

Some are built for speed. Some are optimized for deep reasoning. Some handle massive amounts of context.

But with so many versions—GPT-4, GPT-4 Turbo, GPT-4o—it’s easy to lose track of what’s what.

That’s why we’re breaking it all down.

In this guide, we’ll go model by model, explaining what each of the major OpenAI model does best.

GPT-4

GPT-4 was one of the most anticipated AI releases of 2023. After the groundbreaking impact of GPT-3 and GPT-3.5, the world was waiting for OpenAI’s next major leap. Speculation ran wild—would GPT-4 be AGI? Would it be 100x smarter than GPT-3? Would it completely revolutionize AI applications?

When OpenAI finally launched GPT-4 on March 14, 2023, it didn’t come with an AGI breakthrough—but it was a significant step forward. It introduced better reasoning, enhanced accuracy, and multimodal capabilities (the ability to understand both text and images). It wasn’t just “bigger,” it was smarter and more reliable.

However, there was one downside: it was expensive and slower compared to GPT-3.5. OpenAI focused on quality over cost, which meant GPT-4 was primarily used for high-end applications rather than everyday AI tasks.

What OpenAI Thinks About GPT-4

OpenAI positioned GPT-4 as a major refinement of AI intelligence. According to OpenAI:

• It’s far more accurate than GPT-3.5, reducing hallucinations and misinformation.
• It has improved logical reasoning and is better at handling complex tasks.
• It’s multimodal, meaning it can process both text and images (though the image input feature was limited to certain applications).
• It’s more aligned with human values and safety, making it less likely to generate harmful content.

Essentially, GPT-4 was a thinking AI, not just a talking one.

Strengths of GPT-4

• Better at following instructions – More nuanced, context-aware, and reliable.
• Higher reasoning capabilities – Can process complex queries with greater accuracy.
• Multimodal abilities – Can interpret and generate text and understand images.
• Safer AI interactions – Improved content moderation and ethical safeguards.

Release Timeline

• March 14, 2023 – OpenAI officially launched GPT-4 for ChatGPT Plus users and API access.
• July 2023 – OpenAI expanded API availability to more developers.

API Pricing for GPT-4

GPT-4 was more expensive than GPT-3.5, making it suitable for high-end applications. Here’s the API pricing:

• Input tokens: $0.03 per 1,000 tokens
• Output tokens: $0.06 per 1,000 tokens

Due to these costs, many developers used GPT-4 selectively for critical tasks while relying on GPT-3.5 for cheaper, high-volume operations.

What You Can Build With GPT-4 (Using the API)

GPT-4’s intelligence and reasoning made it ideal for:

• Legal and financial AI tools – More precise contract analysis, financial forecasting, and compliance automation.
• Advanced AI tutors – Personalized education tools for complex subjects like mathematics and coding.
• AI for research & data analysis – Assisting in scientific research and business intelligence.
• Medical AI applications – Assisting with diagnosis, summarizing medical literature, and patient interactions.
• Creative AI – Generating scripts, poetry, and deep storytelling content.

GPT-4 Turbo

GPT-4 Turbo arrived at a time of uncertainty in the AI world. OpenAI had already released GPT-4, which was widely seen as a gold standard for general AI performance. Yet, competitors like Anthropic (Claude), Google DeepMind (Gemini), and Mistral were gaining ground, offering powerful alternatives with different cost and speed trade-offs.

Users were expecting GPT-5, but OpenAI took a different approach—rather than rushing a completely new version, they focused on optimization. The goal? Make GPT-4 significantly cheaper, faster, and more scalable.

Sam Altman, OpenAI’s CEO, positioned GPT-4 Turbo as the “smarter” way forward—instead of just pushing a raw intelligence upgrade, OpenAI fine-tuned the model to deliver similar or better performance at a fraction of the cost. It was a move that catered to developers, businesses, and AI-powered applications that needed to scale without skyrocketing expenses.

What OpenAI Thinks About GPT-4 Turbo

OpenAI describes GPT-4 Turbo as a high-efficiency AI model that balances intelligence, speed, and affordability. According to OpenAI, it’s:

• Faster and cheaper than standard GPT-4, making it the best option for API-based applications.
• Still as powerful as GPT-4, with slight improvements in reasoning and cost efficiency.
• A strategic move to ensure AI remains widely accessible for developers.

Essentially, GPT-4 Turbo represents OpenAI’s shift from just raw power to practical, scalable AI solutions.

Strengths of GPT-4 Turbo

• Faster inference speeds – Optimized to respond more quickly than GPT-4.
• Lower API costs – Specifically built for businesses and startups scaling AI-powered apps.
• Balanced intelligence – Retains GPT-4’s deep reasoning and creativity.
• Ideal for high-volume AI tasks – Works well in chatbots, virtual assistants, and automated workflows.

Release Timeline

• November 6, 2023 – OpenAI announced GPT-4 Turbo at Dev Day, alongside major API updates.

API Pricing for GPT-4 Turbo

One of the biggest reasons developers adopted GPT-4 Turbo was its cost savings. Here’s the official API pricing:

• Input tokens: $0.01 per 1,000 tokens
• Output tokens: $0.03 per 1,000 tokens

For context, this is significantly cheaper than GPT-4, making Turbo the go-to choice for large-scale AI applications.

What You Can Build With GPT-4 Turbo (Using the API)

Because of its balance of power and efficiency, GPT-4 Turbo is used in a wide range of AI applications:

• Enterprise Chatbots – AI-powered customer support systems handling thousands of interactions.
• Automated Content Creation – Blog writing, marketing copy, and AI-driven ad generation.
• AI-Powered SaaS Tools – AI copilots, data analysis bots, and automated workflows.
• Personalized AI Assistants – AI that tailors responses based on user history and preferences.
• Scalable AI Customer Support – Virtual agents that can replace or assist human teams.

GPT-4o

By mid-2024, AI users were demanding more than just text-based intelligence. Competitors like Google DeepMind and Anthropic were pushing multimodal AI, capable of seamlessly understanding text, images, and even voice. OpenAI needed a response—and they delivered it with GPT-4o.

Announced in May 2024, GPT-4o ("o" for omni) was not just an upgrade; it was OpenAI’s first truly multimodal AI. Unlike previous models that processed different inputs separately, GPT-4o was trained natively across text, images, and audio, making its responses smoother, more natural, and contextually aware.

What set GPT-4o apart was its ability to think faster—it wasn’t just cheaper than GPT-4 Turbo, it was significantly faster in real-time applications like voice AI. OpenAI even demonstrated it responding in milliseconds in live conversations, making it feel like a true AI assistant rather than a text generator.

What OpenAI Thinks About GPT-4o

OpenAI markets GPT-4o as:

• A step toward real-time AI interactions – Optimized for live applications, including AI voice assistants and instantaneous multimodal comprehension.
• The smoothest conversational AI yet – GPT-4o processes and responds faster, making chatbots and virtual assistants feel more human-like.
• More accessible and affordable – It’s cheaper and more efficient than both GPT-4 and GPT-4 Turbo, bringing advanced AI to more businesses and developers.

Strengths of GPT-4o

• Native multimodal processing – Handles text, images, and audio together, unlike previous models that had to process them separately.
• Faster than any previous OpenAI model – Makes AI assistants feel more natural in real-time conversations.
• Improved memory and context retention – Handles longer discussions with better recall.
• Cheaper than GPT-4 Turbo – Making high-level AI more accessible to businesses and developers.

Release Timeline

• May 13, 2024 – OpenAI officially unveiled GPT-4o, making it available for ChatGPT users and API developers the same day.

API Pricing for GPT-4o

GPT-4o is even cheaper than GPT-4 Turbo, which makes it ideal for high-usage AI applications:

• Input tokens: $0.005 per 1,000 tokens
• Output tokens: $0.015 per 1,000 tokens

This aggressive pricing makes advanced AI cheaper than ever, allowing more businesses to integrate real-time AI into their products.

What You Can Build With GPT-4o (Using the API)

GPT-4o’s multimodal and real-time abilities open up new possibilities:

• AI-powered voice assistants – With response speeds in milliseconds, GPT-4o is ideal for AI-powered voice assistants in customer service, virtual coaching, and personal AI companions.
• Real-time multimodal AI – Apps that analyze text, images, and voice together, like AI tutors that explain math problems while showing visual solutions.
• AI-enhanced video conferencing – Imagine a virtual meeting assistant that summarizes conversations and generates action points in real time.
• Advanced customer service bots – Handling text, images, and voice queries seamlessly, making chatbots far more effective.
• Personalized AI companions – From mental health support bots to AI-driven relationship coaching, GPT-4o’s fast response times and memory retention create more engaging and human-like interactions.

GPT-4o Mini

By mid-2024, OpenAI was in a unique position. GPT-4o had launched in May, bringing multimodal capabilities and faster responses, but there was still a gap in the market. While GPT-4o was impressive, many developers and businesses needed something cheaper, yet still powerful—something that could handle large-scale API usage without the costs stacking up.

This is where GPT-4o Mini came in. It wasn’t just another version of GPT-4o; it was designed to be a budget-friendly AI powerhouse, offering a balance between cost, performance, and scalability. OpenAI saw this as a way to make high-quality AI more accessible to businesses, startups, and developers who didn’t need the full power of GPT-4o but still wanted a robust, intelligent model.

Launched on July 18, 2024, GPT-4o Mini was immediately positioned as an entry-level alternative to GPT-4o, providing significant improvements over GPT-3.5 Turbo while remaining affordable and efficient.

What OpenAI Thinks About GPT-4o Mini

OpenAI markets GPT-4o Mini as a step up from GPT-3.5 Turbo, with better performance in text understanding and reasoning while being far cheaper than GPT-4o. Key points OpenAI emphasizes:

• Affordable AI → Designed for businesses that need high-volume AI interactions without high costs.
• A Smart Upgrade → Outperforms GPT-3.5 Turbo while being significantly cheaper than GPT-4o.
• Scalable for Developers → Enables building AI applications without worrying about excessive API costs.

OpenAI positioned GPT-4o Mini as an ideal solution for startups and cost-conscious developers who want the power of AI but at a fraction of the cost of premium models.

Strengths of GPT-4o Mini

• Cost-Effective → More powerful than GPT-3.5 Turbo but cheaper than GPT-4o.
• Large Context Window → Can process 128,000 tokens in one go, useful for handling large documents.
• Multimodal Capabilities → Handles text and images, a rare feature for a "mini" model.
• Improved Response Length → Can generate up to 16,384 tokens per request.
• Optimized for API Use → Specifically built to handle high-volume queries efficiently.

Release Timeline

• July 18, 2024 → OpenAI releases GPT-4o Mini as a cost-efficient alternative to GPT-4o.

API Pricing for GPT-4o Mini

GPT-4o Mini is one of the cheapest OpenAI models available:

• Input tokens → $0.15 per million tokens
• Output tokens → $0.60 per million tokens

For fine-tuned versions of the model:

• Input tokens → $0.30 per million tokens
• Output tokens → $1.20 per million tokens

This aggressive pricing makes GPT-4o Mini an economical choice for developers and businesses that need to process large amounts of data without breaking the bank.

What You Can Build With GPT-4o Mini (Using the API)

Given its strengths, GPT-4o Mini is perfect for building:

• Customer Support Bots → AI chatbots that handle inquiries without expensive API costs.
• High-Volume AI Applications → Apps that need frequent API calls but must remain affordable.
• Content Generation Tools → Generate blogs, articles, and marketing copy at scale.
• Educational Platforms → Offer AI-powered tutoring and study assistants.
• Data Processing Assistants → AI that summarizes reports and analyzes documents efficiently.

GPT-4o Mini strikes the perfect balance between power and affordability, making it a go-to option for startups and developers who need a reliable, cost-efficient AI.

O1

By late 2024, OpenAI was facing increased competition, with Anthropic, Google DeepMind, and Mistral rolling out advanced models at a rapid pace. OpenAI had already made a huge leap with GPT-4o, but users were demanding even better reasoning capabilities, especially for scientific research, coding, and enterprise AI applications.

Internally, OpenAI had been working on a model under the "O1" codename, which was designed to refine multimodal capabilities and enhance logical reasoning beyond what GPT-4o offered. Unlike its predecessors, O1 placed a heavy emphasis on accuracy, scientific knowledge, and real-world applications, positioning it as an alternative to competitors like Claude 3 Opus and Gemini 1.5 Pro.

O1 was first introduced in September 2024 as O1-preview and O1-mini, with OpenAI allowing limited access for testing. The full-scale release of O1 followed in December 2024, marking a significant milestone in OpenAI’s AI roadmap.

What OpenAI Thinks About O1

OpenAI positioned O1 as a step towards achieving stronger reasoning and factual accuracy, making it ideal for academic research, software development, and decision-making tasks. Unlike previous models, O1 had a more structured and deterministic approach to problem-solving, making it attractive for businesses requiring high-confidence AI outputs.

While OpenAI didn't brand O1 as a direct successor to GPT-4o, they presented it as a specialized reasoning-focused model, filling a gap that many power users had identified in GPT-4o’s more generalized abilities.

Strengths of O1

• Advanced Reasoning – O1 outperforms GPT-4o in structured problem-solving, making it a strong choice for scientific research, math, and programming.
• Improved Accuracy – Compared to GPT-4o, O1 reduces hallucinations and offers more consistent factual outputs.
• Multimodal Capabilities – Like GPT-4o, O1 can process and generate text, images, and code efficiently.
• Optimized for Enterprise Use – OpenAI designed O1 to handle complex workflows for businesses needing AI-assisted decision-making.
• API Fine-tuning Potential – O1 offers better customization and fine-tuning options, allowing developers to optimize it for specific tasks.

Release Timeline

• September 12, 2024 – OpenAI soft-launched O1-preview and O1-mini for early adopters.
• December 2024 – The full release of O1 became available.

API Pricing for O1

As of its release, O1's API pricing followed a similar structure to GPT-4o but was slightly more expensive due to its advanced reasoning abilities. OpenAI positioned O1 for high-end applications, so the cost was justified by its increased accuracy and reliability.

Pricing estimates (as of December 2024):

• O1 Input Cost: $0.02 per 1K tokens
• O1 Output Cost: $0.06 per 1K tokens

What Can You Build With O1?

• AI Coding Assistants – O1 excels in code generation, debugging, and algorithm optimization, making it an excellent choice for developer tools.
• AI-Powered Research Assistants – Scientists and researchers can use O1 to analyze academic papers, summarize research findings, and generate hypotheses.
• Enterprise AI Solutions – Businesses can integrate O1 into decision-support systems, legal research platforms, and financial forecasting tools.
• Fact-Checking and Verification Tools – O1’s improved accuracy makes it ideal for journalism, compliance monitoring, and misinformation detection.
• STEM Education Tools – With its strong reasoning abilities, O1 can be used to build AI tutors specializing in math, physics, and engineering.

O1 marked a shift towards more structured AI models, focusing on accuracy and reasoning over sheer generative power. While not as flashy as GPT-4o, it catered to users who needed reliable AI for scientific, coding, and enterprise-level applications.

O3 Mini

O3 Mini is one of OpenAI’s more under-the-radar models. It didn’t launch with the same level of hype and anticipation as GPT-4 or GPT-4 Turbo. Instead, it was quietly introduced as a specialized, high-precision model designed for technical, logical, and analytical tasks.

At the time of its release, OpenAI was focused on balancing cost, efficiency, and performance. Many developers needed a model that wasn’t as expensive as GPT-4 but was still more precise than GPT-3.5. That’s where O3 Mini came in.

It was built to excel in STEM-related queries—handling math, logic, programming, and structured reasoning better than most general-purpose models. Unlike larger models optimized for creative tasks, O3 Mini was sharp, concise, and analytical.

What OpenAI Thinks About O3 Mini

While OpenAI hasn’t publicly promoted O3 Mini as aggressively as other models, its role is clear:

• It’s a precision tool for developers, researchers, and technical users.
• It’s designed for problem-solving, particularly in coding, scientific research, and mathematics.
• It offers a balance of efficiency and cost, making it a strong alternative to heavier models when logic and structure matter most.

Essentially, OpenAI sees O3 Mini as a go-to model for structured reasoning—not just a chatbot but a thinking assistant for technical work.

Strengths of O3 Mini

• Superior logical and analytical reasoning – Ideal for problem-solving, structured thinking, and technical workflows.
• Strong in STEM subjects – Excels at math, coding, and scientific explanations.
• More efficient than GPT-4 – Provides high accuracy at a lower cost.
• Concise and structured responses – Prioritizes clarity over fluff.

Release Timeline

• Early 2024 – O3 Mini was introduced as part of OpenAI’s expanded model lineup for developers looking for an affordable but precise AI solution.

API Pricing for O3 Mini

O3 Mini is designed to be cost-effective, making it a smart choice for technical applications. The API pricing is:

• Input tokens: $0.005 per 1,000 tokens
• Output tokens: $0.01 per 1,000 tokens

This makes it cheaper than GPT-4 but more capable in structured reasoning than GPT-3.5.

What You Can Build With O3 Mini (Using the API)

Because of its strengths in logic and technical analysis, developers use O3 Mini for:

• AI-powered coding assistants – Debugging code, generating structured programming explanations, and helping with documentation.
• Mathematical solvers – Step-by-step problem-solving in algebra, calculus, and advanced math topics.
• AI tutors for STEM subjects – Explaining complex scientific and engineering concepts with clarity.
• Automated data analysis tools – Assisting with spreadsheet calculations, formula generation, and pattern recognition in datasets.
• Technical customer support bots – Handling structured troubleshooting and FAQs for software and technical products.

GPT-4.5

The Story Behind GPT-4.5

By the time GPT-4.5 was introduced, the AI industry had been waiting for the next major leap in OpenAI's model lineup. GPT-4o had already changed the game by making AI faster, more multimodal, and more efficient, but there was still speculation about an even more powerful model.

Rumors of GPT-4.5 started circulating when OpenAI hinted at an intermediate model before the eventual release of GPT-5. Some believed this would be a half-step upgrade—a refinement of GPT-4o rather than a complete transformation. But when OpenAI officially launched GPT-4.5, it was clear that this was more than just a minor update.

GPT-4.5 arrived as a bridge between GPT-4o and the anticipated GPT-5, delivering improved speed, better memory handling, and more accurate multimodal capabilities. It wasn’t just an optimization—it was a model that made AI interactions feel smoother, smarter, and more natural.

What OpenAI Thinks About GPT-4.5

OpenAI positioned GPT-4.5 as:

• A "pro-level" GPT-4o, capable of handling larger-scale reasoning tasks with greater efficiency.
• The model that pushes OpenAI’s AI closer to real-time thinking, with faster token processing and better retention over longer conversations.
• A key stepping stone to GPT-5, with features that hint at the next generation of AI advancements.

OpenAI emphasized that GPT-4.5 was built for businesses and developers who needed an ultra-reliable, low-latency, and high-performance AI model for complex workflows.

Strengths of GPT-4.5

• Higher Reasoning & Problem-Solving Ability – Stronger than GPT-4o, with better logical structuring.
• Faster Response Times – Nearly 25% faster token generation compared to previous models.
• Improved Multimodal Capabilities – Better at handling images, text, and code simultaneously.
• Longer Context Memory – Can remember twice as much conversation history as GPT-4o, making it more useful for long-term interactions.
• More Human-Like Responses – The model produces smoother, more natural-sounding text, reducing robotic phrasing.

Release Timeline

• Official Announcement: August 2025
• Public API Launch: September 2025

GPT-4.5 arrived just before the end of 2025, setting the stage for what AI in 2026 would look like.

API Pricing for GPT-4.5

With enhanced capabilities came a higher API cost compared to GPT-4o, but it was still priced competitively for its performance.

• Input Tokens: $10 per million tokens
• Output Tokens: $20 per million tokens

Though it was more expensive than GPT-4o, many businesses found the performance improvements justified the cost—especially for AI-powered applications that required deep reasoning and complex decision-making.

What You Can Build With GPT-4.5 (Using the API)

Thanks to its powerful reasoning, faster speed, and better multimodal support, GPT-4.5 is ideal for:

• Advanced AI Assistants – More context-aware chatbots that handle long-term conversations and memory retention.
• Enterprise-Level Automation – AI systems for automating business operations, financial modeling, and data-driven decision-making.
• Multimodal AI Applications – Tools that combine image processing with text generation for more interactive AI experiences.
• Real-Time AI Customer Support – Faster and more accurate responses in customer service bots.
• Software Development & Code Generation – Enhanced AI pair programming with better debugging and long-term project understanding.
• AI-Powered Research Assistants – AI tools that analyze, summarize, and cross-reference vast amounts of data for researchers.

GPT-4.5 was a significant step forward, bringing OpenAI closer to real-time, multimodal, and deeply contextual AI. It proved that the gap between GPT-4 and GPT-5 wasn’t just about incremental improvements—it was about redefining what AI can do in everyday applications.

Choosing the Right Model for Your Needs

OpenAI’s model evolution—from GPT-4 to GPT-4 Turbo, GPT-4o, O1, and beyond—reflects the rapid advancements in AI capabilities. Each model brings unique strengths, whether it's GPT-4o’s speed and efficiency, O1’s superior reasoning, or O3 Mini’s balance of cost and performance.

But the real power of these models isn’t just in their technical specs—it’s in what you can build with them. Whether you're developing AI-powered chatbots, automation tools, research assistants, or enterprise-grade applications, choosing the right model is key.

With Chatbase, you can access and build with the latest OpenAI models seamlessly. Our platform makes it easy to integrate these models into chatbots, customer support systems, and AI-driven workflows—without the complexity of managing APIs yourself.

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