OpenAI brings GPT-5 to free ChatGPT with an automatic selector
OpenAI is making GPT-5 ChatGPT’s default model, including for free accounts. The system decides when to answer instantly and when to spend more compute on reasoning, with announced improvements in coding, healthcare and reliability.
OpenAI launched GPT-5 on Thursday, making its new flagship model the default in ChatGPT for signed-in users, including those on the free tier. The change is more than a capability upgrade: the company wants users to stop having to choose between a fast model and one that spends more time reasoning.
GPT-5 arrives nearly three years after ChatGPT popularized generative AI, and with an unusual distribution scale: OpenAI says the service now has more than 700 million weekly users. That makes the launch significant beyond benchmark comparisons: any improvement or mistake in the model will quickly flow into millions of everyday conversations, tasks and decisions.
A model that decides how much to think
The company describes GPT-5 as a unified system. It combines the speed of the GPT family with the reasoning capabilities introduced in the o-series models, which break down complex problems before answering.
An internal router analyzes each request and decides whether to provide an immediate response or activate a more intensive reasoning mode. The goal is to reduce a friction that had become commonplace in ChatGPT: manually choosing which model to use and figuring out when it is worth spending more computing time.
In practice, a simple question should get a quick answer, while a coding, analysis or planning request may be routed through a longer process. Paid subscribers retain more control and higher usage limits. The Plus plan, at $20 a month, expands access; the Pro plan, at $200 a month, includes unlimited use of GPT-5 and GPT-5 Pro, a version that uses more resources to tackle difficult problems.
OpenAI is also adding four configurable personalities to ChatGPT — Cynic, Robot, Listener and Nerd. They do not change the system’s knowledge, only the style in which it responds. It is a meaningful product decision: the company wants the assistant to adapt to user preferences without turning every conversation into a collection of instructions about tone.
Coding, science and a promise of fewer hallucinations
OpenAI says GPT-5 is particularly competitive at coding. On SWE-bench Verified, a test based on real issues from GitHub repositories, it scored 74.9% on its first attempt. That is slightly above Claude Opus 4.1’s 74.5% and clearly ahead of Gemini 2.5 Pro’s 59.6%, according to results compared by the company.
That is a significant result for people who use AI to build complete applications from a description, a practice known as vibe coding. But it does not mean the model can replace a programmer’s review: SWE-bench measures bounded problems, and a rate near 75% still leaves one in four unresolved on the first attempt.
GPT-5 Pro scored 89.4% on GPQA Diamond, a PhD-level science question exam, and 42% on Humanity’s Last Exam when using tools. On the latter test, it fell short of the 44.4% reported for Grok 4 Heavy. The new model therefore does not top every frontier leaderboard; OpenAI is presenting an advantage in specific areas, not an insurmountable lead over Anthropic, Google or xAI.
The most practical improvement may be reliability. OpenAI says GPT-5 with reasoning produced incorrect or fabricated answers in 4.8% of cases in its evaluation of responses to ChatGPT prompts, compared with 22% for o3 and 20.6% for GPT-4o. Hallucinations are plausible but false answers, one of the problems that most limits the professional use of these systems.
In healthcare, the company puts GPT-5’s hallucination rate with reasoning at 1.6% on HealthBench Hard Hallucinations, compared with 12.9% for GPT-4o and 15.8% for o3. That would be a meaningful improvement if confirmed in real-world use, but it does not turn the chatbot into a healthcare professional. Interpreting symptoms, clinical results or treatments still requires medical judgment and data that a conversational model cannot verify on its own.
The developer offering is changing too
GPT-5 is available through OpenAI’s API in three sizes: gpt-5, gpt-5-mini and gpt-5-nano. The variants let developers balance cost, speed and reasoning capacity depending on the task. The company has also added a verbosity control so developers can specify whether they want more concise or more extensive responses.
The flagship model costs $1.25 per million input tokens and $10 per million output tokens. A token is a unit of text that models use to process and generate language; it does not exactly correspond to a word. The difference between input and output matters for products that generate long reports, code or detailed answers: producing text remains considerably more expensive than reading it.
The release comes just days after OpenAI published gpt-oss, a family of open-weight reasoning models that companies and developers can download and run themselves. With GPT-5, the company is maintaining a complementary strategy: offering open models for certain uses while reserving its most advanced system for ChatGPT and its commercial infrastructure.
Team, Edu and Enterprise accounts will receive GPT-5 as their default model next week. The next test will not be another benchmark chart, but whether the automatic selector consistently makes the right call, whether the model reduces errors outside internal tests and whether its improvements justify the cost for those building products on the API.
