Claude Opus 4.6 vs GPT-5.3-Codex
A side-by-side comparison of two multimodal models — real specs, pricing, strengths and weaknesses, and a clear verdict on which to choose. Kept current by our agents.
Quick verdict: which should you choose?
Choose Claude Opus 4.6 if you need
- ✓Choose Claude Opus 4.6 if you need effective handling of large inputs up to 1M tokens.
- ✓Choose Claude Opus 4.6 if you need strong performance on nuanced reasoning tasks.
- ✓Choose Claude Opus 4.6 if you need careful safety-aligned responses and high-quality structured outputs.
Choose GPT-5.3-Codex if you need
- ✓Choose GPT-5.3-Codex if you need faster output at 101.39 t/s versus 40.23 t/s.
- ✓Choose GPT-5.3-Codex if you need lower cost at $14 per million tokens versus $25.
- ✓Choose GPT-5.3-Codex if you need a model specialized for programming workflows.
- ✓Choose GPT-5.3-Codex if you need support for diverse input types with 400k context.
Verdict
GPT-5.3-Codex leads with a higher intelligence index (53.6 vs 52.9), over twice the output speed, and lower price, making it stronger for coding and high-volume use. Claude Opus 4.6 counters with a much larger 1M-token context window and strengths in nuanced reasoning plus safety-aligned structured outputs. The choice hinges on whether specialized speed or broad careful handling of massive inputs matters more.
Claude Opus 4.6 vs GPT-5.3-Codex: side by side
| Spec | Claude Opus 4.6 | GPT-5.3-Codex | Winner |
|---|---|---|---|
| Intelligence | 52.9 | 53.6 | GPT-5.3-Codex |
| Output speed | 40 t/s | 101 t/s | GPT-5.3-Codex |
| Output price | $25.00/1M | $14.00/1M | GPT-5.3-Codex |
| Context | 1000K | 400K | Claude Opus 4.6 |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | Anthropic | OpenAI | Tie |
Detailed analysis
Intelligence
Winner: GPT-5.3-CodexGPT-5.3-Codex scores 53.6 on the intelligence index compared to Claude Opus 4.6's 52.9. This gives it a slight edge in overall capability. Claude still shows advantages in nuanced reasoning per its listed strengths.
Speed
Winner: GPT-5.3-CodexGPT-5.3-Codex delivers 101.39 tokens per second while Claude Opus 4.6 runs at 40.23 t/s. Claude's limitations note slower response times on complex queries. This makes B clearly faster for throughput.
Pricing
Winner: GPT-5.3-CodexGPT-5.3-Codex costs $14 per million output tokens versus Claude Opus 4.6 at $25. The lower price pairs with its speed advantage. Both remain proprietary closed models from their providers.
Context Window
Winner: Claude Opus 4.6Claude Opus 4.6 supports a 1,000,000-token context compared to GPT-5.3-Codex's 400,000 tokens. Its strengths explicitly include effective handling of large inputs. This gives A the advantage for very long documents or conversations.
Claude Opus 4.6
Pros
- +Strong performance on nuanced reasoning tasks
- +Careful and safety-aligned responses
- +Effective handling of large inputs
- +High-quality structured outputs
Cons
- –Slower response times on complex queries
- –More conservative on borderline topics
- –No native real-time web access
GPT-5.3-Codex
Pros
- +Specialized for programming workflows
- +Extensive context handling
- +Support for diverse input types
Cons
- –Narrower focus than general-purpose models
- –Performance tied to input quality
Summary: Claude Opus 4.6 vs GPT-5.3-Codex
Select GPT-5.3-Codex when speed, cost, and coding focus are priorities. Opt for Claude Opus 4.6 when maximum context size and careful nuanced reasoning matter most. Both excel in multimodal tasks but target different workflow needs.
Frequently asked questions
GPT-5.3-Codex is better for speed and cost with a higher intelligence index, while Claude Opus 4.6 is better for large context and nuanced reasoning.