OpenAI updates GPT-5.1 for smarter, more personal conversations

OpenAI has begun rolling out GPT-5.1, an updated version of its large language models, to ChatGPT users, starting with paid subscribers.

The company said GPT-5.1 includes two variants: Instant, which is designed for faster and more conversational responses, and Thinking, which focuses on advanced reasoning and adapts response times to question complexity.

OpenAI reported improvements in math and coding tasks, and said the new models offer more natural communication.

Users will gain new controls to customize ChatGPT’s tone and style, with preset options like Professional, Friendly, Candid, Quirky, Efficient, Nerdy, and Cynical.

Fine-tuning for tone, conciseness, and other response characteristics will be tested with some users this week.

OpenAI plans to release GPT-5.1 Instant and Thinking to its API later in the week, with legacy GPT-5 remaining available for paid users for three months.

The update will be rolled out gradually to maintain platform stability.

🔗 Source: OpenAI

🧠 Food for thought

Implications, context, and why it matters.

Token costs and latency still unclear after OpenAI performance claims

OpenAI says math and coding got better. Pricing and latency benchmarks (response-time ranges) remain missing. Context window sizes (how much text the model can process at once) and rate limits (API request caps) are not public. These gaps make it hard to judge if GPT-5.1 Instant is worth a switch from GPT-5 or rivals.
GPT-5.1 Thinking adjusts response time to question complexity 1, uses fewer tokens on easy tasks, and takes longer on hard prompts. Without latency ranges or cost per token data (billing units for chunks of text), buyers cannot model total cost of ownership (TCO).
OpenAI is rolling this out slowly, which hints at infrastructure stress tests, and legacy GPT-5 stays for three months 1. The timeline pushes migration without a clear cost-benefit view for paid ChatGPT users.

New tone controls create openings for third-party tooling providers

New tone presets are available 1. They include Professional and Friendly. Other options are Candid, Quirky, and Efficient. Nerdy and Cynical round out the set. Direct emoji control plus tone tweaks create room for Software-as-a-Service (SaaS) vendors to build brand voice tools for chatbots.
AI infrastructure startups can use tone and conciseness fine-tuning to build evaluation frameworks. These tools track output consistency and let enterprises A/B test (randomized split testing) conversational styles against conversion metrics.
Fine-tuning adapts models through training on custom datasets 2. Teams need at least 100 to 200 high quality prompt-completion examples (input-output pairs) to see gains, which pushes third-party tooling providers to build strong data collection and validation workflows for enterprise clients.