Is ChatGPT 5 Reliable Examining Its 25 Percent Error Rate

A recent study focusing on OpenAI’s ChatGPT-5 model has revealed that it produces incorrect answers in roughly one-quarter of its responses. According to a report by Tom’s Guide, these inaccuracies are rooted in the fundamental limitations of the model's training data and its probabilistic approach to reasoning.

A Major Leap Forward from GPT 4

Despite the identified error rate, the model represents a significant advancement over its predecessor, GPT-4. It demonstrates a 45% reduction in factual mistakes and produces six times fewer “hallucinated” or completely fabricated answers. However, the study also confirms that ChatGPT-5 can still suffer from overconfidence, a trait where it presents false information with a high level of certainty. While the frequency of hallucinations has decreased, its persistence remains a key challenge for the model's overall reliability.

Performance Varies Across Different Tasks

The accuracy of ChatGPT-5 is not uniform and changes significantly based on the task at hand. For instance, in a highly structured domain like mathematics, it achieved an impressive 94.6% accuracy on the 2025 AIME test. In contrast, its success rate dropped to 74.9% on a series of real-world coding challenges. The research highlights that errors are more likely to occur in tasks that depend on general knowledge or involve complex, multi-step reasoning, where the model's performance is less dependable.

Understanding the Root Causes of Errors

When tested against the MMLU Pro benchmark, a comprehensive academic evaluation covering subjects like science, math, and history, ChatGPT-5 achieved an accuracy score of approximately 87%. The study pinpointed several underlying reasons for the remaining errors. These include an inability to fully grasp the nuance in complex questions, a reliance on training data that might be outdated or incomplete, and the model's core design as a probabilistic tool that predicts plausible patterns rather than verifying factual correctness.

The Verdict A Call for Cautious Use

Given these findings, the report strongly advises users to independently verify any critical information generated by ChatGPT-5. This recommendation is particularly important for professional, academic, or health-related inquiries where accuracy is paramount. The persistent error rate, even with substantial improvements, highlights the ongoing need for careful application and external validation of the model's outputs.

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