Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | GPT-5.5 Instant (June 2026) | Claude Opus 5 (Adaptive Reasoning, Low Effort) |
|---|---|---|
| Input ($/M tokens) | $5 | $5 |
| Output ($/M tokens) | $30 | $25 |
Verdict. Claude Opus 5 (Adaptive Reasoning, Low 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, Low Effort) is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Claude Opus 5 (Adaptive Reasoning, Low Effort) makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. GPT-5.5 Instant (June 2026) is strongest on Coding Index (39.4), Intelligence Index (29.2). Claude Opus 5 (Adaptive Reasoning, Low Effort) leads on Coding Index (66.9), Intelligence Index (52.5).
Speed. On throughput, GPT-5.5 Instant (June 2026) generates tokens at 117 tok/s versus 49 tok/s — about 58% faster. On time-to-first-token, GPT-5.5 Instant (June 2026) responds in 950ms vs 3450ms, which matters most for chat-style UIs.
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 (June 2026) costs $600.00 ($7200/year); Claude Opus 5 (Adaptive Reasoning, Low Effort) costs $525.00 ($6300/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): GPT-5.5 Instant (June 2026) ≈ $85.00/run, Claude Opus 5 (Adaptive Reasoning, Low Effort) ≈ $75.00/run. At agent/realtime scale (200M input / 100M output per million requests): GPT-5.5 Instant (June 2026) ≈ $4000/run, Claude Opus 5 (Adaptive Reasoning, Low Effort) ≈ $3500/run. Claude Opus 5 (Adaptive Reasoning, Low 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.
Head-to-head deltas
Data from Artificial Analysis API — 12 benchmarks
Claude Opus 5 (Adaptive Reasoning, Low 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 (June 2026).
Claude Opus 5 (Adaptive Reasoning, Low Effort) wins 2 out of 12 benchmarks compared to 0 for GPT-5.5 Instant (June 2026). See the detailed benchmark chart above for per-category results.
GPT-5.5 Instant (June 2026) generates tokens faster at 117 tok/s vs 49 tok/s. GPT-5.5 Instant (June 2026) also has lower time-to-first-token (0.95s vs 3.45s).
Choose based on your priorities: Claude Opus 5 (Adaptive Reasoning, Low Effort) for lower cost, Claude Opus 5 (Adaptive Reasoning, Low Effort) for stronger benchmark performance, and GPT-5.5 Instant (June 2026) for faster generation. For latency-sensitive apps, check the TTFT comparison above.