AnalysisFebruary 12, 2026
Benchmark Wars: Claude Opus 4.6 vs Codex 5.3 - Who Really Wins?
Deep analysis of the February 2026 benchmark competition between Anthropic's Opus 4.6 and OpenAI's Codex 5.3.
The February 2026 Benchmark War
Both Anthropic and OpenAI released major coding models on February 5, 2026.
Head-to-Head Results
| Benchmark | Opus 4.6 | Codex 5.3 | Winner |
| SWE-bench | 82.1% | 76.8% | Opus 4.6 |
| Terminal-Bench | 68.4% | 77.3% | Codex 5.3 |
| GPQA Diamond | 88.5% | 81.9% | Opus 4.6 |
The Real Winner
Neither model dominates all scenarios. Opus 4.6 excels at complex reasoning while Codex 5.3 leads in speed and terminal tasks.