OpenAI has released GPT-5.1, the latest update in the GPT-5 generation of models. While it remains part of the GPT-5 family, this version introduces improvements in reasoning and conversational quality.
GPT-5.1 will become the default model for Mediacorp ChatGPT Enterprise users soon. Further updates will be provided in this article once the rollout begins.
About GPT-5.1
GPT-5.1 is an upgraded series within the GPT-5 generation designed to deliver more natural interactions. It introduces improvements to two core models (Instant and Thinking):
- GPT 5.1 Auto: This is not a model, but the routing system that decides which GPT-5.1 model (Instant or Thinking) to use for each request. Similar to GPT-5 Auto, it selects the most suitable model for each query. This means that in most cases, users do not need to choose a model manually, as ChatGPT automatically determines the best fit.
- GPT-5.1 Instant: A fast, conversational model with a warmer default tone and stronger instruction-following capabilities.
- GPT-5.1 Thinking: A more advanced reasoning model that adjusts its thinking time depending on task complexity. This version of the Thinking model generates outputs that are easier to understand and produces more thorough responses for challenging problems while delivering quicker answers for simpler ones.
Both GPT‑5.1 Instant and GPT‑5.1 Thinking will be available in the API. GPT-5.1 Instant will be released as gpt-5.1-chat-latest and GPT-5.1 Thinking will appear as gpt-5.1, both with adaptive reasoning capabilities.
Key improvements
Below is a consolidated view of the main enhancements introduced in GPT-5.1:
| Improvement area | What’s new in GPT-5.1 | Model |
| Tone | Warmer and more natural dialogue than GPT-5 | GPT 5.1 Instant |
| Instruction Following | More consistent adherence to constraints and task-specific rules than GPT-5 | All GPT-5.1 models |
| Adaptive Reasoning | Can determine when to “think” longer for complex queries, producing more thorough responses. This was previously not available in GPT-5 | GPT-5.1 Instant |
| Dynamic Thinking | Varies its thinking time more dynamically than GPT‑5 Thinking. | GPT-5.1 Thinking |
| Technical Jargon | Clearer, plain-language explanations than GPT-5 | GPT-5.1 Thinking |
| Performance on Benchmarks | Notable gains in reasoning, coding and math evaluations compared to GPT-5 | All GPT-5.1 models |
Model Transition to Legacy Status
Older models will move into legacy status following the launch of GPT-5.1. Conversations using older models will automatically open in their closest GPT-5.1 equivalent.
| Retired models | Closest GPT-5 equivalent |
| GPT-5 | GPT-5.1 Instant |
| GPT-5 Thinking | GPT-5.1 Thinking |
Mediacorp users will still be able to access legacy models by clicking the model dropdown list.
How Will the Launch of GPT-5.1 Affect ChatGPT Enterprise Users?
1. Usage
The default model for ChatGPT Enterprise will automatically transition from GPT-5 to GPT-5.1. No action is required from users.
2. Custom-GPTs
Until 12 January 2026, all custom GPTs will continue using their current model. After this date, legacy models will be retired and all custom GPTs will automatically switch to GPT-5.1. Builders can manually update their custom GPTs to GPT-5.1 any time before the automatic switch.
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