Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | GPT-5.5 Instant (May 2026) | Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) |
|---|---|---|
| Input ($/M tokens) | $5 | $5 |
| Output ($/M tokens) | $30 | $25 |
Verdict. Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) 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 1.2× the per-million-token cost, Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. GPT-5.5 Instant (May 2026) is strongest on Intelligence Index (34.3). Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) leads on Coding Index (77.0), Intelligence Index (62.5).
Speed. Speed data is incomplete for this pair; benchmark and price should decide.
Provider. OpenAI and Anthropic sell to overlapping but distinct developer audiences: OpenAI tends to ship frontier reasoning models with premium positioning, while Anthropic 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): GPT-5.5 Instant (May 2026) costs $600.00 ($7200/year); Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) costs $525.00 ($6300/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): GPT-5.5 Instant (May 2026) ≈ $85.00/run, Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) ≈ $75.00/run. At agent/realtime scale (200M input / 100M output per million requests): GPT-5.5 Instant (May 2026) ≈ $4000/run, Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) ≈ $3500/run. Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) 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.
Data from Artificial Analysis API — 12 benchmarks
Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) is cheaper overall. Its blended price (3:1 input/output ratio) is $10.00/M tokens vs $11.25/M for GPT-5.5 Instant (May 2026).
Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) wins 2 out of 12 benchmarks compared to 0 for GPT-5.5 Instant (May 2026). See the detailed benchmark chart above for per-category results.
Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) generates tokens faster at 55 tok/s vs — tok/s. However, Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) has lower time-to-first-token (32.99s vs —s).
Choose based on your priorities: Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) for lower cost, Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) for stronger benchmark performance, and Claude Opus 5 (Adaptive Reasoning, Xhigh Effort) for faster generation. For latency-sensitive apps, check the TTFT comparison above.