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GPT-5.3 Codex vs Claude Opus 4.6
A detailed comparison of GPT-5.3 Codex (OpenAI) and Claude Opus 4.6 (Anthropic) across pricing, performance, and features.
Pricing Comparison
| Metric | GPT-5.3 Codex | Claude Opus 4.6 | Difference |
|---|---|---|---|
| Input / 1M tokens | $2.00 | $5.00 | +150% |
| Output / 1M tokens | $16.00 | $25.00 | +56% |
| Context window | 200K | 200K | — |
| Max output | 65.536K | 32K | — |
Benchmark Comparison
| Benchmark | GPT-5.3 Codex | Claude Opus 4.6 |
|---|---|---|
| MMLU-Pro | 90% | 89.5% |
| HumanEval | 96.5% | 95% |
| GPQA | 78% | 75.5% |
Capabilities
| Capability | GPT-5.3 Codex | Claude Opus 4.6 |
|---|---|---|
| code | ✓ | ✓ |
| reasoning | ✓ | ✓ |
| text | ✓ | ✓ |
| tool-use | ✓ | ✓ |
| vision | ✓ | ✓ |
GPT-5.3 Codex Strengths
- ✓Best coding model from OpenAI
- ✓Large output window (65K tokens)
- ✓Strong reasoning for complex tasks
GPT-5.3 Codex Weaknesses
- ✗API access not yet available
- ✗Premium pricing
Claude Opus 4.6 Strengths
- ✓Best-in-class agentic tool use and coding
- ✓1M context available in beta (Tier 4)
- ✓Strong at following complex multi-step instructions
Claude Opus 4.6 Weaknesses
- ✗Premium pricing ($10/$37.50 at 1M context)
- ✗1M context beta is Tier 4 only
Quick Verdict
Best value: GPT-5.3 Codex is the more affordable option at $2/$16 per 1M tokens.
Higher benchmarks: GPT-5.3 Codex scores higher on average across available benchmarks (88.2% avg).
Choose GPT-5.3 Codex if cost matters most. Choose Claude Opus 4.6 if you need the best possible quality for complex tasks.