What the S1 model is and how it differs
The S1 model is an AI language model developed by OpenAI, released in late 2024 as part of their reasoning-focused research initiative. Unlike standard language models that generate responses quickly, S1 is designed to spend more computational time working through complex problems step-by-step before answering. This approach trades speed for accuracy on tasks that benefit from deliberate reasoning — mathematics, logic puzzles, coding problems, and multi-step analysis.
The core difference between S1 and models like GPT-4o or Claude 3.5 Sonnet is how they handle difficult questions. Standard models aim to answer immediately. S1 shows its reasoning process, sometimes spending seconds or minutes on a single response, similar to how a person might work through a hard math problem on paper before stating the answer.
S1 is not a general replacement for other models. It excels at specific problem types but may be slower and less efficient for straightforward tasks like summarizing text, answering factual questions, or having a conversation. The choice between S1 and alternatives depends on what you are trying to do.
Key Takeaways
- S1 is built for reasoning-heavy tasks like mathematics and coding, while GPT-4o and Claude 3.5 Sonnet are faster for general writing and information retrieval.
- S1 shows its working and takes longer to respond, which helps on complex problems but slows down everyday tasks.
- Pricing differs by model: S1 costs more per token than standard models because of the extra computation required.
- Access to S1 is currently limited to ChatGPT Plus subscribers and API users with specific tier access, while GPT-4o and Claude are more widely available.
- For most writing, research, and customer-facing work, standard models remain faster and more cost-effective than S1.
S1 versus GPT-4o for reasoning and problem-solving
GPT-4o is OpenAI's general-purpose model, designed for speed and breadth across writing, coding, analysis, and conversation. It handles most tasks well but does not always show strong reasoning on problems that require multiple logical steps. On a difficult math problem or a tricky coding challenge, GPT-4o may rush to an answer and make mistakes.
S1 approaches the same problems differently. It allocates computational resources to think through the problem, testing approaches and catching errors before finalizing the response. On standardized reasoning benchmarks, S1 scores significantly higher than GPT-4o on mathematics and logic tasks. However, S1 is slower — a response that takes GPT-4o milliseconds may take S1 several seconds or longer.
For everyday tasks like drafting emails, summarizing documents, or answering factual questions, GPT-4o remains the better choice. S1 shines when you need confidence in the correctness of a complex solution and are willing to wait for it.
S1 versus Claude 3.5 Sonnet for accuracy and speed
Claude 3.5 Sonnet, made by Anthropic, is positioned similarly to GPT-4o — a fast, general-purpose model that handles writing, coding, and analysis. Like GPT-4o, Claude 3.5 Sonnet prioritizes speed and can struggle with multi-step reasoning problems where a wrong first step leads to a wrong answer.
S1 and Claude 3.5 Sonnet take opposite approaches to the accuracy-speed trade-off. Claude 3.5 Sonnet is faster and better for most practical tasks. S1 is slower but more reliable on problems where reasoning matters. If you are building a chatbot or writing assistant, Claude 3.5 Sonnet is the practical choice. If you are solving a research problem or debugging complex code, S1 may catch errors that Claude 3.5 Sonnet would miss.
Pricing also differs. Claude 3.5 Sonnet costs less per token than S1, making it more economical for high-volume applications. S1's higher cost reflects the extra computation required for reasoning.
When to use S1 instead of other models
S1 is worth using when the cost of a wrong answer is high and the task involves reasoning. Examples include verifying mathematical proofs, debugging production code, solving logic puzzles, or working through multi-step scientific problems. If you are checking whether a solution is correct before relying on it, S1's reasoning transparency helps you spot errors.
S1 is not the right choice for speed-critical applications. If you are running a customer support chatbot, generating content at scale, or answering simple factual questions, standard models like GPT-4o or Claude 3.5 Sonnet are faster and cheaper. S1 is also not necessary for creative writing, brainstorming, or tasks where multiple valid answers exist.
The practical decision often comes down to whether you need to see the reasoning. If you just want an answer, GPT-4o or Claude 3.5 Sonnet will get you there faster. If you need to understand how the model arrived at the answer and verify it is correct, S1 justifies the wait and cost.
Cost and access differences
S1 is more expensive than GPT-4o or Claude 3.5 Sonnet because it uses more computational resources. OpenAI charges per token, and S1 tokens cost roughly 2 to 3 times more than GPT-4o tokens, depending on whether you are using input or output tokens. For a single complex problem, this difference may be negligible. For high-volume applications, it adds up quickly.
Access to S1 is currently restricted. It is available to ChatGPT Plus subscribers (the $20-per-month tier) and to API users with specific access levels. GPT-4o and Claude 3.5 Sonnet have wider availability — GPT-4o is available to free ChatGPT users and Claude 3.5 Sonnet is available through Anthropic's free tier. If you need to use S1 at scale through an API, you will need to contact OpenAI about access and pricing.
Comparison table: S1 versus other models
| Feature | S1 | GPT-4o | Claude 3.5 Sonnet |
|---|---|---|---|
| Best for | Complex reasoning, math, coding verification | General writing, coding, analysis | General writing, coding, analysis |
| Speed | Slow (seconds to minutes) | Fast (milliseconds) | Fast (milliseconds) |
| Shows reasoning | Yes, always | No, unless asked | No, unless asked |
| Cost per token | High | Medium | Medium |
| Free access | No (Plus tier only) | Yes (free tier available) | Yes (free tier available) |
| API availability | Limited, requires approval | Widely available | Widely available |
Frequently Asked Questions
Is S1 better than GPT-4o for everything?
No. S1 is better only for tasks that benefit from step-by-step reasoning, like complex math or debugging. For writing, summarizing, answering questions, and most everyday tasks, GPT-4o is faster and sufficient. S1 is a specialist tool, not a replacement for general-purpose models.
Can I use S1 for free?
S1 is not available on the free ChatGPT tier. You need a ChatGPT Plus subscription ($20 per month) to use S1 through the web interface. API access to S1 requires approval from OpenAI and is not available to all users.
How much slower is S1 than other models?
S1 typically takes several seconds to a few minutes per response, depending on problem complexity. GPT-4o and Claude 3.5 Sonnet respond in milliseconds. For a single difficult problem, the wait may be worth it. For high-volume tasks, the slowness makes S1 impractical.
Should I use S1 or Claude 3.5 Sonnet for coding?
For writing code quickly, Claude 3.5 Sonnet is the better choice. For debugging complex code or verifying that a solution is correct before deployment, S1's reasoning transparency helps catch errors. Many developers use Claude 3.5 Sonnet for speed and S1 for verification on critical code.
Will S1 replace GPT-4o?
No. OpenAI has indicated that S1 and GPT-4o serve different purposes. GPT-4o will remain the default for most tasks because it is faster and cheaper. S1 will remain a specialized tool for reasoning-heavy work. Both will likely continue to exist and improve separately.