GPT-4.5: Key Improvements

OpenAI has introduced GPT-4.5, a major upgrade bridging GPT-4 and future models. This release enhances AI development by expanding unsupervised learning, boosting intelligence and capabilities. Initially available to ChatGPT Pro users and developers via API, GPT-4.5 offers a research preview of OpenAI’s most advanced model. This post summarizes GPT-4.5’s improvements, compares it with previous models, explores its use cases, and discusses its impact, including user feedback and API considerations.

Key Improvements in GPT-4.5

GPT-4.5 builds on GPT-4’s architecture with significant enhancements. The focus was on scaling unsupervised learning and fine-tuning alignment for better reasoning and accuracy. Major improvements include:

Expanded Unsupervised Learning: Leveraging a larger corpus and more compute, GPT-4.5 has a broader knowledge base, improving pattern recognition and context relevance, reducing knowledge gaps.
Improved Reasoning Abilities: With stronger logical reasoning and problem-solving skills, GPT-4.5 effectively tackles complex questions, showing improvements in tasks requiring nuance and multi-step reasoning.
Lower Hallucination Rates: A significant reduction in hallucinations, with a rate of around 5%, enhances reliability. This improvement stems from better content understanding and alignment during fine-tuning.

These enhancements make GPT-4.5 interactions more natural and effective. OpenAI’s evaluations highlight its broader knowledge, better user intent alignment, and higher emotional intelligence, with fewer hallucinations.

"Interacting with GPT-4.5 feels more natural. Its broader knowledge, stronger user intent alignment, and improved emotional intelligence make it ideal for writing, programming, and problem-solving — with fewer hallucinations."

comparison chatgpt models performance — a comparative performance table for three AI models: GPT-4.5, GPT-4o, and OpenAI o3-mini, across various benchmark evaluations.

GPT-4.5 significantly outperforms GPT-4o in all categories, particularly in science (71.4% vs 53.6%) and coding tasks.
OpenAI o3-mini excels in science and math, reflecting its reasoning capabilities, but underperforms in coding and multilingual tasks compared to GPT-4.5.
Multilingual and multimodal benchmarks (MMLU & MMMU) show strong performance from GPT-4.5, indicating its broad language understanding.

Comparison with Previous Models

Model	Accuracy (General Performance)	Hallucination Rate (Lower is better)
GPT-3.5 (ChatGPT)	~80% – Capable but often imperfect on complex tasks.	~15% – Occasionally fabricated facts under pressure.
GPT-4	~90% – Highly accurate on a wide range of queries.	~10% – Less hallucination than GPT-3.5, but not infallible.
GPT-4.5	~95% – Best-in-class performance, handling most queries with expert-level accuracy.	~5% – Rarely produces incorrect information; more trustworthy responses.

Note: These values are illustrative averages; actual performance can vary by task. GPT-4.5’s hallucinations were about 40% less frequent than GPT-4’s.