OpenAI o3 is our most powerful reasoning model that pushes the frontier across coding, math, science, visual perception, and more. It sets a new SOTA on benchmarks including Codeforces, SWE-bench (without building a custom model-specific scaffold), and MMMU. It’s ideal for complex queries requiring multi-faceted analysis and whose answers may not be immediately obvious. It performs especially strongly at visual tasks like analyzing images, charts, and graphics. In evaluations by external experts, o3 makes 20 percent fewer major errors than OpenAI o1 on difficult, real-world tasks- especially excelling in areas like programming, business/consulting, and creative ideation. Early testers highlighted its analytical rigor as a thought partner and emphasized its ability to generate and critically evaluate novel hypotheses - particularly within biology, math, and engineering contexts.
OpenAI o4-mini (and o4-mini-high) is a smaller model optimized for fast, cost-efficient reasoning - it achieves remarkable performance for its size and cost, particularly in math, coding, and visual tasks. It is the best-performing benchmarked model on AIME 2024 and 2025. In expert evaluations, it also outperforms its predecessor, o3‑mini, on non-STEM tasks as well as domains like data science. Thanks to its efficiency, o4-mini supports significantly higher usage limits than o3, making it a strong high-volume, high-throughput option for questions that benefit from reasoning.
General Questions
What usage limits will be enforced on OpenAI o3 models on ChatGPT?
Enterprise & Edu users receive 100 messages per week with o3. For o4‑mini, the limit is 300 messages per day and o4-mini-high will be capped at 100 messages/day.
Once you’ve reached your usage limit, you can check the date that your usage limit resets by highlighting the model name in the model picker drop-down. Your weekly usage limit resets every seven days after sending your first message. For example, if you started sending messages on April 22, your limit will reset on April 29 (00:00 UTC), regardless of when you reached your limit.
What is the reasoning behind having these limits in place?
These new models offer significantly better reasoning and multimodal abilities (and now tool use!), which increases compute cost. Per‑user caps ensure stable and consistent service for everyone while we scale capacity.
Are the limits based on individual usage, overall team usage, or a combination of both?
Limits are enforced per individual user. Workspace‑level usage of GPT‑4o and other models remains unaffected.
How will these limits be enforced? (e.g., notifications, access restrictions, overage charges, etc.)
When you reach a limit, the model option is temporarily grayed out in the picker and a tooltip shows the exact reset time. There are no overage fees.
What happens if we exceed the limit? Are there penalties, service disruptions, or extra fees?
There are no penalties or fees. You will simply be unable to select the model again until the quota resets (daily for o4‑mini and o4-mini-high / weekly for o3).
ChatGPT Usage Limits
Will individual users be notified directly, or is this the responsibility of account administrators?
Individual users see in‑product notifications and the model becomes unavailable. Admins do not need to manage anything.
Can we see our current usage against these new limits? Is there a dashboard or report to monitor usage?
At this time there is no per‑user dashboard. Hovering over the model name in the picker displays your personal reset date.
Will there be more limits or restrictions in the future? Should we expect more changes, and what might they be?
Usage limits may evolve as capacity grows. For the latest, please see OpenAI o3 and o4-mini Usage Limits on ChatGPT and the API.
For most tool‑heavy workflows we still recommend GPT‑4o, but unlike the legacy o1 models, o3 and o4‑mini supports the use of advanced tools. For more details, check out the original blog post.
API
What’s the context window for OpenAI o3 and o4-mini models?
In ChatGPT and the API, o3 and o4‑mini both have a 200k token context window, and max output tokens of 100k.
Are the OpenAI o3 and o4‑mini models supported in the Enterprise Compliance API?
Yes. Inputs and outputs are exported via the Compliance API just like other models.
How can I access the OpenAI o3 API?
Developers in usage tiers 4 and 5 automatically receive access. Tiers 1‑3 can unlock access by completing Organization Verification.
Rate limits are published in our Platform API documentation.
What are the main differences between o3 and o4‑mini API?
Capability – o3 delivers the best reasoning and multimodal performance. o4‑mini is lighter and faster, ideal for cost‑sensitive workloads.
Performance – o3 may outperform o4‑mini on highly complex tasks. o4‑mini can be faster for simple chat or code generation.
Cost & rate limits – o4‑mini has lower cost per token and higher throughput ceilings.
Are there any limitations to the OpenAI o3 / o4‑mini API?
The models fully support function calling, streaming, JSON mode, and system messages. Fine‑tuning is not yet available.
Are the OpenAI o3 / o4‑mini API models available to Rescap customers?
Yes – eligibility aligns with the standard zero data retention (ZDR) program. Qualified Rescap customers can request access via their account team.
Are the OpenAI o3 / o4‑mini API models ZDR eligible?
Yes. Trusted customers approved for zero data retention remain eligible when using these models. Learn more about data retention on the OpenAI API.
Can I finetune the OpenAI o3 / o4‑mini API models?
Fine‑tuning capabilities are not yet available for these models.