GPT-5 is the fifth and current flagship model in OpenAI’s Generative Pre-trained Transformers (GPT) series. It was launched on 7 August 2025 and represents a further development of its predecessor models, including GPT-4 and its variants. GPT-5 is designed as a large multimodal language model capable of processing and generating text, images and audio content.
Definition and architecture of GPT-5
GPT-5 is a comprehensive system designed to integrate both rational and non-rational functions within a unified user interface. A key innovation is the real-time router, which automatically determines whether a fast, high-throughput model should be used for routine queries or a more in-depth ‘thinking model’ for complex thought processes. This eliminates the need for users to switch manually between specialised models.
The model was trained from scratch as a native multimodal system, meaning it was developed simultaneously with different data modalities such as text and images, rather than building on pre-trained language or vision models. The training process involved unsupervised pre-training, supervised fine-tuning and reinforcement learning using human feedback.
Key features and capabilities
GPT-5 offers a range of significant improvements and new features:
- Advanced reasoning capabilities: The model demonstrates a significantly improved ability to solve multi-step problems, interpret ambiguous questions and provide detailed justifications for its answers. It can carry out complex logical chains and decide independently when swift action or in-depth reflection is required.
- Enhanced multimodality: GPT-5 can process not only text but also images and audio as input and generate corresponding outputs. This enables more complex interactions and applications.
- Reduced hallucinations: Compared to earlier models, GPT-5 exhibits a drastically lower rate of hallucinations in fact-based tasks. When web search is enabled, the likelihood of factual errors is reduced by 45 per cent compared to GPT-4o, and in reasoning mode, error rates are reduced by as much as 80 per cent compared to earlier reasoning models.
- Longer context window: For API users, GPT-5 supports a combined input and output context length of up to 400,000 tokens. This enables the processing of more extensive documents and longer conversations.
- Improved programming capabilities: The model achieves a performance of 74.9 per cent on benchmarks such as SWE-bench Verified and 88 per cent on Aider Polyglot. It is more efficient than previous models and, during high-intensity reasoning tasks, requires 22 per cent fewer output tokens and 45 per cent fewer tool calls to achieve similar results.
- Agency functions: GPT-5 can independently set up a desktop and use a browser to research relevant sources for a task on its own.
- Availability: GPT-5 is available to all ChatGPT users as the default model and is accessible to developers via the OpenAI API. There are various variants, such as
gpt-5,gpt-5-miniandgpt-5-nano, which are optimised for different requirements in terms of speed, cost and depth of reasoning.
