GPT-4 Turbo was a revolutionary model when it arrived in 2023, but the evolution of OpenAI It didn't stop there. From GPT-4o to GPT-5 and its variants, each generation has brought significant improvements in speed, multimodal capabilities, and reasoning. In this updated guide for 2026, I'll explain the entire evolutionary line, with real comparisons so you can choose the model that best suits your needs.
📋 Quick summary: evolution in numbers
- GPT-4 Turbo (Nov 2023): 128,000 context tokens, known as of Dec 2023, $10/$30 per million tokens (input/output)
- GPT-4o (May 2024): 128K tokens, native multimodal (text + image + audio), 50% cheaper than Turbo
- GPT-4.1 (April 2025): 1 million Context tokens, leader in coding, $2/$8 per million tokens
- GPT-5 (August 2025): 400,000 tokens, advanced reasoning, autonomous agents, $1.25/$10 per million tokens
- GPT-5.4 (2026): 1.05 million tokens, current flagship model, $2.50/$15 per million tokens
The complete timeline: from GPT-4 Turbo to GPT-5
| Model | Launch | Context | API Price (in/out) | Main new feature |
|---|---|---|---|---|
| GPT-4 Turbo | November 2023 | 128K tokens | $10 / $30 | 4x more context than GPT-4, faster and cheaper |
| GPT-4o | May 2024 | 128K tokens | $5 / $15 | Native multimodal: text, image and audio in a single model |
| o1 | September 2024 | 128K tokens | $15 / $60 | Step-by-step reasoning |
| O3 | Dec 2024 | 200k tokens | $10 / $40 | Enhanced reasoning with computational flexibility |
| GPT-4.1 | April 2025 | 1 million tokens | $2 / $8 | First model with 1M context, leader in coding |
| GPT-5 | August 2025 | 400K tokens | $1.25 / $10 | Reasoning + multimodal + agents in a unified system |
| GPT-5.2 | December 2025 | 400K tokens | $1.75 / $14 | Professional work: spreadsheets, presentations, complex projects |
| GPT-5.4 | 2026 | 1.05 million tokens | $2.50 / $15 | Flagship model: complex reasoning and advanced coding |
Prices in dollars per million tokens. Source: OpenAI Pricing.
What did each model bring that was new?
GPT-4 Turbo — The Modern Foundation
Launched in November 2023, it quadrupled the context window (from 32K to 128K tokens) and reduced costs by up to 3x compared to GPT-4. It introduced JSON Mode and improved instruction following. It was the industry standard for months.
GPT-4o — Native multimodal
In May 2024, OpenAI introduced GPT-4o (“omni”): the first model that natively processes text, image, and audio within a single neural network. It responds in ~320 ms (human-like), supports 50+ languages, and was offered for free on ChatGPT. Additionally, it cost half as much as Turbo on the API (this was retired in February 2026).
Series o1/o3 — Deep Reasoning
With o1 (September 2024) and o3 (December 2024), OpenAI introduced specialised models for “thinking before responding”. They use internal chains of thought to solve mathematical, logical, and scientific problems with superior accuracy, albeit with increased latency and cost.
GPT-4.1 — 1 million tokens
Launched in April 2025, GPT-4.1 was OpenAI’s first model with 1 million context tokens. It achieved a score of 54.6% on SWE-bench Verified (outperforming GPT-4 by 21%), becoming the benchmark for programming tasks. Available in three variants: standard, mini and nano.
GPT-5 — The generational leap
In August 2025, GPT-5 arrived: a unified system combining reasoning, multimodal processing (text, image, audio, video) and autonomous agent capabilities. According to Sam Altman, it offers “PhD-level” skills across a broad range of tasks. Better code, fewer hallucinations, and faster responses.
GPT-5.2 / 5.4 — The present
GPT-5.2 (December 2025) focused on professional work: spreadsheets, presentations, and multi-step projects. GPT-5.4, OpenAI's current flagship model, extends context to 1.05 million tokens and leads in complex reasoning and code generation.
Which model should you use in 2026?
Practical tip: You don’t always need the latest model. If you use ChatGPT Plus, you already have access to GPT-5 and its variants. But if you’re working with the API, choosing the right model can save you a lot of money. GPT-4.1 nano costs just $0.10 per million input tokens and is excellent for simple, high-volume tasks.
| If you need... | Use this template | Why? |
|---|---|---|
| General chat, everyday questions | GPT-5 (ChatGPT) | Already included in ChatGPT Free and Plus, ideal balance |
| Programming and debugging | GPT-5.4 / GPT-4.1 | Leaders in coding benchmarks (SWE-bench) |
| Analyse long documents | GPT-5.4 / GPT-4.1 | Context of 1M+ tokens for books, contracts, code |
| Mathematical/scientific reasoning | O3 | Designed to think step-by-step with high accuracy |
| Large-scale simple tasks (API) | GPT-4.1 nano | The cheapest: $0.10/1M input tokens |
| Professional work (documents, spreadsheets) | GPT-5.2 | Optimised for multi-step business tasks |
Things to bear in mind
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GPT-4 Turbo is already obsolete. OpenAI has marked GPT-4 Turbo as a model legacy. If you are still using it in your API, consider migrating to GPT-4.1 or GPT-5 for better performance at a lower cost.
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Newer isn't always more expensive. GPT-5 costs 1.25 TP4T per million input tokens, compared to GPT-4 Turbo’s 10 TP4T per million. This evolution has brought both improvements and price reductions.
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The “o” models are complementary, not replacements. The o1/o3 series exists in parallel to GPT-5. Use the “o” models when you need deep reasoning and GPT-5 for general tasks.
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Check your plan's limits. ChatGPT Free provides access to GPT-5 but with message limits. ChatGPT Plus offers up to 5x more capacity and access to advanced models like o3 and GPT-5.4.
Frequently asked questions
Is GPT-4 Turbo still available in 2026?
Technically yes, but it's marked as a model legacy by OpenAI. This means it will continue to function for a while but will not receive updates and will eventually be retired. It is recommended to migrate to GPT-4.1 or GPT-5, which offer better performance at a lower price.
GPT-4o is the latest model from OpenAI, while GPT-5 is a future model.
GPT-4o was OpenAI's first native multimodal model (May 2024), capable of processing text, image, and audio. GPT-5 (August 2025) takes this further: it unifies advanced reasoning, multimodal processing (including video), and autonomous agent capabilities into a single system. Furthermore, GPT-5 has a lower hallucination rate and faster responses.
Can I use GPT-5 for free?
Yes. As with GPT-4o, OpenAI is offering GPT-5 on the free version of ChatGPT, albeit with message limits. ChatGPT Plus subscribers have access with much higher limits and can also use advanced models like o3 and GPT-5.4.
Which OpenAI model is best for programming?
In March 2026, OpenAI’s best models for programming are GPT-5.4 and GPT-4.1. GPT-4.1 achieved a score of 54.6% on SWE-bench Verified, and its 1-million-token window is ideal for working with large repositories. GPT-5.4 combines this capability with more advanced reasoning.
How much does it cost to use GPT-5 on the API?
The base GPT-5 costs $1.25 per million input tokens and $10 per million output tokens. GPT-5.2 rises to $1.75/$14, and GPT-5.4 (the most capable model) costs $2.50/$15. All are significantly cheaper than GPT-4 Turbo, which cost $10/$30.
Do you want to better understand how these models work and how to get the most out of them?
Read the basic guide to ChatGPTKeep exploring
- What is GPT artificial intelligence? — The fundamentals behind this entire family of models
- GPT-4o free: everything you need to know The story of the model that democratised access
- Claude vs ChatGPT (2025) — How does GPT-5 compare against its main competitor
Last updated: March 2026. Prices and availability are subject to change. Please check the OpenAI pricing page for updated information.
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