GPT-5

GPT-5 is the fifth major generation of the Generative Pre-trained Transformer (GPT) family developed by OpenAI. Released on 7 August 2025, it is a multimodal model capable of processing and reasoning over text and images, and it was made available through ChatGPT, Microsoft Copilot, and the OpenAI API. Its defining architectural idea is unification: rather than shipping separate fast and slow models, GPT-5 operates as a single system that decides when to answer quickly and when to spend additional computation "thinking" through a problem before responding.

Design and capabilities

Earlier OpenAI products drew a hard line between conversational models optimised for speed, such as GPT-4o, and dedicated reasoning models, such as the o-series, that traded latency for accuracy on hard problems. GPT-5 merges these behaviours behind an internal router that assesses the difficulty of a request and allocates inference effort accordingly. Simple queries return with low latency, while multi-step mathematical, scientific, or coding tasks trigger longer deliberation.

At release, OpenAI reported state-of-the-art results across several public benchmarks: roughly 94.6% on the AIME 2025 mathematics competition without tool use, 74.9% on SWE-bench Verified for real-world software engineering, 88% on the Aider Polyglot coding benchmark, and 84.2% on the MMMU multimodal understanding test. The company also emphasised reliability, reporting that GPT-5 responses were around 45% less likely to contain a factual error than GPT-4o, and that when the model engaged its reasoning mode, factual errors fell by roughly 80% relative to the earlier o3 model.

Reduced hallucination and health performance

A central claim for GPT-5 was a measurable reduction in hallucination, the tendency of language models to state false information confidently. OpenAI reported improved scores on HealthBench Hard, a demanding medical-reasoning evaluation, alongside broader gains in writing quality and instruction following. These improvements positioned GPT-5 for higher-stakes domains such as clinical decision support, financial analysis, and legal drafting, though OpenAI continued to advise human oversight in all such settings.

Successor models

GPT-5 anchored a rapid release cadence. In December 2025 OpenAI introduced GPT-5.2, described as its flagship reasoning model, with improvements in general intelligence, long-context understanding, agentic tool-calling, and computer vision. In April 2026 the company released GPT-5.5, which focused on agentic coding, computer use, and knowledge work, followed by a GPT-5.5 Instant variant positioned as a fast default model for ChatGPT. This sequence reflected an industry-wide shift toward agentic systems that reason across context and take actions over extended tasks rather than producing single-turn answers.

Comparison with peers

GPT-5 competes directly with Anthropic's Claude family, Google's Gemini models, and open-weight alternatives such as Llama and DeepSeek.

| Dimension | GPT-5 approach | | --- | --- | | Reasoning | Unified fast/slow routing in one model | | Modality | Text and image input | | Deployment | Proprietary API and consumer apps | | Positioning | General-purpose assistant and agent backbone |

The competitive landscape in 2025 and 2026 centred less on raw benchmark scores and more on reliability, cost per token, tool-use fidelity, and the ability to sustain multi-step autonomous work.

References

1. OpenAI. (2025). Introducing GPT-5. openai.com.
2. Wikipedia contributors. (2026). GPT-5. en.wikipedia.org.
3. TechCrunch. (2026). OpenAI releases GPT-5.5 Instant, a new default model for ChatGPT. techcrunch.com.
4. Built In. (2025). GPT-5: What's New in OpenAI's Latest ChatGPT Model?. builtin.com.