Quick answer

GPT-5 is OpenAI's most capable model to date. It reasons better, makes fewer mistakes, handles much longer documents, and is significantly more reliable on complex tasks than GPT-4. It is the main reason OpenAI crossed $25 billion in annual revenue — businesses are paying for it because it actually works better.

OpenAI has been on a remarkable run. GPT-4 launched in 2023 and was a huge leap. Then came GPT-4o (faster), GPT-4o mini (cheaper), and now GPT-5 — the first model that OpenAI openly describes as a step change in reasoning ability, not just a speed or cost improvement. Here is what actually changed.

What is actually new in GPT-5?

  • Much stronger reasoning — GPT-5 can work through multi-step problems (maths, logic, planning) with significantly fewer errors
  • Longer context — can read and reason over entire books, codebases, or legal documents in one go
  • Better instruction-following — it does what you actually ask, not a plausible version of it
  • Fewer hallucinations — especially on factual claims and citations
  • Improved tool use — better at using web search, code execution, and file reading reliably
  • Multimodal by default — processes text, images, audio, and video natively

How is it different from GPT-4?

The simplest way to understand it: GPT-4 was a very good writer. GPT-5 is a very good thinker. The jump is most obvious on tasks that require multiple steps — planning a project, writing code that actually runs, analysing a document and drawing specific conclusions. GPT-4 would often get the early steps right and then drift. GPT-5 stays on track.

Benchmark result: GPT-5 scores above 90% on the GPQA Diamond benchmark — questions designed to stump PhD-level experts. GPT-4 scored around 53%. This is not a marginal improvement.

Who should upgrade to GPT-5?

  • Developers — if you are building AI-powered products, GPT-5's improved reliability dramatically reduces the need for error handling
  • Researchers and analysts — the stronger reasoning and reduced hallucination rate makes it trustworthy for deeper work
  • Lawyers, accountants, consultants — long document processing and reliable extraction of specific details
  • Casual users — honestly, the free tier (GPT-4o mini) is still excellent for everyday tasks; GPT-5 is where the gap matters most for professional use

Is GPT-5 available to use right now?

Yes. GPT-5 is available via the ChatGPT interface (ChatGPT Plus and above) and via the OpenAI API. It is more expensive per token than GPT-4o — roughly 3-4x the cost — which is why OpenAI also keeps the cheaper models available. Most developers use a tiered approach: GPT-4o mini for simple tasks, GPT-5 for complex ones.

How does it compare to Claude and Gemini?

In April 2026, GPT-5 leads on reasoning benchmarks. Claude 3.5 Opus is still preferred by many for long-form writing and document analysis (and has a larger context window for some use cases). Gemini Ultra is competitive and has the advantage of native Google integration. The honest answer: they are all excellent, and the "best" model depends on your specific use case.

Related reading

Is Claude Actually Beating ChatGPT Now? The 2026 AI Leaderboard Shift Claude Opus 4.7 — What Is New and Why It Is the Most Capable AI Yet ChatGPT vs Claude vs Gemini — Which AI Is Actually Better? How Does ChatGPT Actually Work? The Non-Technical Explanation

Bottom line

GPT-5 is a genuine step forward — not just a marketing update. If you have been frustrated by AI making logic errors, going off-track on complex tasks, or hallucinating specific facts, GPT-5 is meaningfully better at all three. It is worth trying, especially if AI is part of your professional work.