Compare / head-to-head
Claude Opus 4.5vs
GPT-5-Codex
Claude Opus 4.5 leads 2 of 2 shared benchmarks. GPT-5-Codex is 2.7x cheaper per token. GPT-5-Codex has the larger context window (400K tokens).
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
2 – 0
Claude Opus 4.5 leads
Cheaper per token
GPT-5-Codex
2.7x cheaper, input + output
Larger context
GPT-5-Codex
400K tokens
Providers
2 providers
Anthropic · OpenAI
Claude Opus 4.5
Anthropic · released 2025-11-24
textvision
GPT-5-Codex
OpenAI · released 2025-09-15
textvision
Quality
Benchmark matrix
2 shared · 36 only Claude Opus 4.5 · 0 only GPT-5-Codex| Benchmark | Claude Opus 4.5 | GPT-5-Codex | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 2 | ||||
| SWE-bench Verified | 80.9% ↗ | 74.5% ↗ | +6.4 pt | Claude Opus 4.5 |
| WeirdML (Håvard Tveit Ihle) | 63.7% ↗ | 54.5% ↗ | +9.2 pt | Claude Opus 4.5 |
| Only Claude Opus 4.5 reports · 36 | ||||
| GPQA Diamond | 87% ↗ | not reported | — | — |
| LMArena Elo | 1473.6 ↗ | not reported | — | — |
| ARC-AGI-2 (Verified) | 37.6% ↗ | not reported | — | — |
| BALROG (BALROG) | 43.5% ↗ | not reported | — | — |
| Chess Puzzles (Epoch AI run) | 12% ↗epoch run | not reported | — | — |
| EBR-bench (Epoch AI run) | 14.3% ↗epoch run | not reported | — | — |
| FrontierMath Tier 4 v2 (Epoch AI run) | 4.9% ↗epoch run | not reported | — | — |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 34.4% ↗epoch run | not reported | — | — |
| Furniture Assembly (Epoch AI run) | 28.3% ↗epoch run | not reported | — | — |
| GSO Opt@1 (GSO) | 24.5% ↗ | not reported | — | — |
| LiveBench Agentic Coding (LiveBench) | 39.7% ↗ | not reported | — | — |
| LiveBench Coding (LiveBench) | 79.7% ↗ | not reported | — | — |
| LiveBench Data Analysis (LiveBench) | 74.4% ↗ | not reported | — | — |
| LiveBench Instruction Following (LiveBench) | 62.5% ↗ | not reported | — | — |
| LiveBench Language (LiveBench) | 81.3% ↗ | not reported | — | — |
| LiveBench Mathematics (LiveBench) | 90.4% ↗ | not reported | — | — |
| LiveBench Reasoning (LiveBench) | 80.1% ↗ | not reported | — | — |
| LMArena WebDev (LMArena) | 1493.3 ↗ | not reported | — | — |
| MCP Atlas | 62.3% ↗ | not reported | — | — |
| MMMLU | 90.8% ↗ | not reported | — | — |
| MMMU (validation) | 80.7% ↗ | not reported | — | — |
| Mystery Game Puzzles (Epoch AI run) | 22% ↗epoch run | not reported | — | — |
| OSWorld | 66.3% ↗ | not reported | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | 86.1% ↗epoch run | not reported | — | — |
| SAGE (Vals AI) | 52.1% ↗ | not reported | — | — |
| SimpleBench (SimpleBench) | 62% ↗ | not reported | — | — |
| SimpleQA Verified | 45.7% ↗epoch run | not reported | — | — |
| SWE-bench Verified (Epoch AI run) | 76.7% ↗epoch run | not reported | — | — |
| tau2-bench Airline (Sierra) | 84% ↗ | not reported | — | — |
| tau2-bench Banking Knowledge (Sierra) | 24.7% ↗ | not reported | — | — |
| tau2-bench Retail (Sierra) | 79.6% ↗ | not reported | — | — |
| tau2-bench Telecom (Sierra) | 92.3% ↗ | not reported | — | — |
| Terminal-Bench 2.0 | 59.3% ↗ | not reported | — | — |
| Vending-Bench 2 (Andon Labs) | 4967.06 ↗ | not reported | — | — |
| τ2-bench (Retail) | 88.9% ↗ | not reported | — | — |
| τ2-bench (Telecom) | 98.2% ↗ | not reported | — | — |
| Only GPT-5-Codex reports · 0 | ||||
| GPT-5-Codex reports nothing Claude Opus 4.5 does not. | ||||
Scores tagged "epoch" or "matharena" are independent runs, used only where the lab has not published its own; ⚠ marks rows MathArena flags as released after the competition. Higher is better on every row. Δ is Claude Opus 4.5 minus GPT-5-Codex in the benchmark's own unit. "Not reported" means the lab has not published that figure; it is not a zero. ↗ opens the source.
Specs & pricing
Side by side
Official pricing pages and model cards| Spec | Claude Opus 4.5 | GPT-5-Codex | Edge |
|---|---|---|---|
| Context window | 200K tokens | 400K tokens | GPT-5-Codex |
| Max output | 64K tokens | 128K tokens | GPT-5-Codex |
| Input price / 1M | $5 ↗ | $1.25 ↗ | GPT-5-Codex |
| Output price / 1M | $25 ↗ | $10 ↗ | GPT-5-Codex |
| Cached input / 1M | $0.5 ↗ | $0.125 ↗ | GPT-5-Codex |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $30 | $11.25 | GPT-5-Codex |
| Modalities | text · vision | text · vision | Tie |
| Released | 2025-11-24 | 2025-09-15 | — |
| Cited benchmark scores | 39 | 2 | — |
Reliability
Provider status
Live from /statusMore matchups
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Which one wins on your data?
Public benchmarks are a starting point. Run Claude Opus 4.5 and GPT-5-Codex on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.