Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | Claude Opus 4.5 (Reasoning) | GPT-5.5 (xhigh) |
|---|---|---|
| Input ($/M tokens) | $5 | $5 |
| Output ($/M tokens) | $25 | $30 |
Verdict. GPT-5.5 (xhigh) takes the aggregate benchmark matchup 2–0 across 2 categories. Real workloads usually care about a handful of specific tasks — see the per-benchmark table above.
Pricing. Both models sit in the premium bracket for output-token pricing. At 0.8× the per-million-token cost, Claude Opus 4.5 (Reasoning) is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Claude Opus 4.5 (Reasoning) makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. Claude Opus 4.5 (Reasoning) is strongest on Intelligence Index (41.9). GPT-5.5 (xhigh) leads on Coding Index (74.9), Intelligence Index (56.3).
Speed. On throughput, GPT-5.5 (xhigh) generates tokens at 85 tok/s versus 46 tok/s — about 46% faster. On time-to-first-token, Claude Opus 4.5 (Reasoning) responds in 11190ms vs 68860ms, which matters most for chat-style UIs.
Provider. Anthropic and OpenAI sell to overlapping but distinct developer audiences: Anthropic tends to ship frontier reasoning models with premium positioning, while OpenAI often prices more aggressively. Your existing vendor relationships, billing, and SLA preferences may matter as much as the raw numbers above.
Workload cost. Workload scenarios (per million requests at 30M input + 15M output tokens): Claude Opus 4.5 (Reasoning) costs $525.00 ($6300/year); GPT-5.5 (xhigh) costs $600.00 ($7200/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): Claude Opus 4.5 (Reasoning) ≈ $75.00/run, GPT-5.5 (xhigh) ≈ $85.00/run. At agent/realtime scale (200M input / 100M output per million requests): Claude Opus 4.5 (Reasoning) ≈ $3500/run, GPT-5.5 (xhigh) ≈ $4000/run. Claude Opus 4.5 (Reasoning) becomes more attractive at higher volume — the absolute per-token pricing difference compounds when you ship at scale.
Recommendation. Both models have legitimate use cases — the right answer depends on whether you are optimizing for benchmark ceiling, latency, or unit cost. Start with the cheaper / faster model, evaluate against your specific task, and only switch if the upgrade shows a meaningful lift.
Head-to-head deltas
Data from Artificial Analysis API — 12 benchmarks
Claude Opus 4.5 (Reasoning) is cheaper overall. Its blended price (3:1 input/output ratio) is $10.00/M tokens vs $11.25/M for GPT-5.5 (xhigh).
GPT-5.5 (xhigh) wins 2 out of 12 benchmarks compared to 0 for Claude Opus 4.5 (Reasoning). See the detailed benchmark chart above for per-category results.
GPT-5.5 (xhigh) generates tokens faster at 85 tok/s vs 46 tok/s. Claude Opus 4.5 (Reasoning) also has lower time-to-first-token (11.19s vs 68.86s).
Choose based on your priorities: Claude Opus 4.5 (Reasoning) for lower cost, GPT-5.5 (xhigh) for stronger benchmark performance, and GPT-5.5 (xhigh) for faster generation. For latency-sensitive apps, check the TTFT comparison above.