OpenAI o3: The Reasoning Model That Thinks Before Answering
OpenAI's o3 model achieves 87.7% on GPQA Diamond and 96.7% on AIME 2024 through extended chain-of-thought reasoning, redefining what's possible in AI problem-solving.

OpenAI's o3 model achieves 87.7% on GPQA Diamond and 96.7% on AIME 2024 through extended chain-of-thought reasoning, redefining what's possible in AI problem-solving.

TL;DR
OpenAI released o3 in December 2024, following o1 with even more sophisticated reasoning capabilities. Unlike standard models that generate answers immediately, o3 deliberates -spending seconds or minutes working through problems step-by-step before responding. This "thinking time" enables PhD-level performance on complex reasoning tasks previously beyond AI capabilities.
For applications requiring rigorous problem-solving -scientific research, advanced mathematics, complex code generation -o3 represents a capability leap.
| Benchmark | o3 (high) | o1 | GPT-4o | Human expert |
|---|---|---|---|---|
| GPQA Diamond (PhD science) | 87.7% | 78.3% | 56.1% | 69.7% |
| AIME 2024 (math competition) | 96.7% | 83.3% | 13.4% | ~60% |
| Codeforces (competitive programming) | 2727 Elo | 1891 Elo | 808 Elo | 1500-1800 |
| HumanEval (code generation) | 96.7% | 92.0% | 90.2% | N/A |
o3 surpasses human PhD holders on science questions and matches top competitive programmers.
"Focus is the ultimate competitive advantage. The companies that win are the ones saying no to 99% of opportunities to double down on the 1% that matters." - Naval Ravikant, Founder of AngelList
User: "Solve this differential equation..."
Model: [Generates answer immediately]
Latency: 0.8s
User: "Solve this differential equation..."
Model: [Thinks for 15s]
- Analyzing equation structure
- Considering integration methods
- Testing substitution approach
- Verifying boundary conditions
- Double-checking algebra
[Generates answer]
Latency: 15.4s
Trade-off: 10-20× longer latency for significantly higher accuracy on complex problems.
| Mode | Thinking time | Accuracy gain | Price (input/output) |
|---|---|---|---|
| Low | 5-10s | +15% vs GPT-4o | $5/$15 per M tokens |
| Medium | 20-40s | +35% vs GPT-4o | $15/$60 per M tokens |
| High | 60-300s | +50% vs GPT-4o | $50/$200 per M tokens |
Choose based on problem complexity and latency tolerance.
Task: "Propose experimental design to test [hypothesis]"
o3 approach:
Output quality: Comparable to postdoc-level experimental design.
Task: "Implement a distributed consensus algorithm"
o3 reasoning:
Result: Production-ready code with edge cases handled.
Task: "Prove [complex theorem]"
o3 process:
Choose o3 if:
Choose GPT-4o if:
Scenario: Generate solution to competitive programming problem
| Approach | Success rate | Attempts needed | Total cost |
|---|---|---|---|
| GPT-4o (multiple attempts) | 25% | 4 | $0.08 |
| o3 low (single attempt) | 70% | 1.4 | $0.35 |
| o3 high (single attempt) | 95% | 1.05 | $1.50 |
o3 high costs more but often cheaper overall due to higher first-attempt success rate.
Call-to-action (Awareness stage) Test o3's reasoning on complex problems in the OpenAI Playground (select o3 model).
OpenAI skipped "o2" to avoid trademark conflicts with UK telecom company O2.
Not in API currently -thinking is internal. Visible in Playground for debugging.
Yes, can invoke tools during reasoning process.
Configurable up to 5 minutes in high mode; auto-stops if solution found earlier.
Yes, generally available as o3 model ID.
OpenAI o3 achieves breakthrough performance on complex reasoning tasks by spending extended time deliberating before answering. Best suited for scientific research, advanced mathematics, and sophisticated code generation where accuracy justifies 10-20× higher latency and cost. Standard models remain better for conversational AI and simple tasks.
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