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Claude Sonnet 4.5 vs o3
A detailed comparison of Claude Sonnet 4.5 (Anthropic) and o3 (OpenAI) across pricing, performance, and features.
Pricing Comparison
| Metric | Claude Sonnet 4.5 | o3 | Difference |
|---|---|---|---|
| Input / 1M tokens | $3.00 | $0.40 | -87% |
| Output / 1M tokens | $15.00 | $1.60 | -89% |
| Context window | 200K | 200K | — |
| Max output | 16K | 100K | — |
Benchmark Comparison
| Benchmark | Claude Sonnet 4.5 | o3 |
|---|---|---|
| MMLU-Pro | 84.5% | 87% |
| HumanEval | 93% | 94.5% |
| GPQA | 68.2% | 79.2% |
Capabilities
| Capability | Claude Sonnet 4.5 | o3 |
|---|---|---|
| code | ✓ | ✓ |
| reasoning | ✓ | ✓ |
| text | ✓ | ✓ |
| tool-use | ✓ | ✓ |
| vision | ✓ | ✓ |
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- ✗Superseded by Sonnet 4.6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
o3 Strengths
- ✓Recently repriced — now very cheap
- ✓Excellent logical reasoning
- ✓200K context window
o3 Weaknesses
- ✗Slower due to reasoning overhead
- ✗Overkill for simple tasks
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.