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o3 vs Claude Sonnet 4.5
A detailed comparison of o3 (OpenAI) and Claude Sonnet 4.5 (Anthropic) across pricing, performance, and features.
Pricing Comparison
| Metric | o3 | Claude Sonnet 4.5 | Difference |
|---|---|---|---|
| Input / 1M tokens | $0.40 | $3.00 | +650% |
| Output / 1M tokens | $1.60 | $15.00 | +838% |
| Context window | 200K | 200K | — |
| Max output | 100K | 16K | — |
Benchmark Comparison
| Benchmark | o3 | Claude Sonnet 4.5 |
|---|---|---|
| MMLU-Pro | 87% | 84.5% |
| HumanEval | 94.5% | 93% |
| GPQA | 79.2% | 68.2% |
Capabilities
| Capability | o3 | Claude Sonnet 4.5 |
|---|---|---|
| code | ✓ | ✓ |
| reasoning | ✓ | ✓ |
| text | ✓ | ✓ |
| tool-use | ✓ | ✓ |
| vision | ✓ | ✓ |
o3 Strengths
- ✓Recently repriced — now very cheap
- ✓Excellent logical reasoning
- ✓200K context window
o3 Weaknesses
- ✗Slower due to reasoning overhead
- ✗Overkill for simple tasks
Claude Sonnet 4.5 Strengths
- ✓Well-tested and stable
- ✓Strong coding and analysis
Claude Sonnet 4.5 Weaknesses
- ✗Superseded by Sonnet 4.6
- ✗Same price as the newer model
Quick Verdict
Best value: o3 is the more affordable option at $0.4/$1.6 per 1M tokens.
Higher benchmarks: o3 scores higher on average across available benchmarks (86.9% avg).
Choose o3 if cost matters most. Choose Claude Sonnet 4.5 if you need the best possible quality for complex tasks.