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What is o3-mini? OpenAI's Reasoning Model Explained (2026)
What is o3-mini? OpenAI’s Reasoning Model Explained (2026)
o3-mini is OpenAI’s accessible reasoning model that “thinks” through problems before responding. It delivers o1-level performance at lower latency and cost, with 150 messages/day for ChatGPT Plus users. Optimized for STEM tasks, math, and complex reasoning.
How o3-mini Works
Unlike traditional AI models that generate responses immediately, o3-mini uses “private chain-of-thought” reasoning:
- Receives your question
- Thinks through the problem (extended processing)
- Works step-by-step internally
- Outputs well-reasoned answer
This approach dramatically improves accuracy on complex problems.
Key Capabilities
Extended Reasoning
- Works through multi-step problems
- Shows logical progression
- Better at complex tasks
STEM Excellence
- Mathematics (calculus, proofs)
- Coding (algorithms, debugging)
- Science (physics, chemistry)
- Logic puzzles
Search Integration
- Real-time web search
- Up-to-date information
- Source citations
Lower Latency
Compared to o1:
- Faster responses
- Same quality output
- More efficient processing
Specifications
| Spec | Value |
|---|---|
| Daily limit (Plus) | 150 messages |
| API input | $1.10/M tokens |
| API output | $4.40/M tokens |
| Search | Yes |
| Vision | Limited |
o3-mini vs Other Models
| Feature | o3-mini | GPT-4o | o1 |
|---|---|---|---|
| Reasoning | Extended | Standard | Extended |
| Speed | Medium | Fast | Slower |
| STEM | Excellent | Good | Excellent |
| Creative | Good | Excellent | Good |
| Cost | Low | Low | High |
| Daily limit | 150 | Higher | Lower |
When to Use o3-mini
Use o3-mini for:
- Complex math problems
- Algorithm design
- Scientific analysis
- Code debugging
- Logical reasoning
- Research questions
Use GPT-4o instead for:
- Quick questions
- Creative writing
- General conversation
- Image generation
- Faster responses
Examples
Math Problem
Prompt: Prove that the square root of 2 is irrational.
o3-mini: [Shows complete proof with logical steps,
using proof by contradiction, demonstrating why
assuming √2 is rational leads to a contradiction]Coding Task
Prompt: Find the bug in this binary search code
and explain the fix.
o3-mini: [Analyzes code step-by-step, identifies
off-by-one error, explains why it occurs, provides
corrected version with explanation]The o3 Family
| Model | Use Case | Cost |
|---|---|---|
| o3-mini | Daily reasoning (best value) | $ |
| o3 | Maximum accuracy | $$$ |
| o1 (legacy) | Being replaced by o3 | $$ |
How to Access
In ChatGPT
- Open ChatGPT
- Click model selector
- Choose “o3-mini”
- Enter reasoning task
Via API
from openai import OpenAI
client = OpenAI()
response = client.chat.completions.create(
model="o3-mini",
messages=[{"role": "user", "content": "Your question"}]
)Performance Highlights
OpenAI’s testing shows:
“o3-mini delivered results on par with o1 at a lower latency, and outperformed o1-mini on advanced STEM tasks.”
This makes o3-mini the default choice for most reasoning tasks.
Related Questions
Last verified: March 11, 2026