Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) | Claude Opus 5 (Adaptive Reasoning, Max Effort) |
|---|---|---|
| Input ($/M tokens) | $10 | $5 |
| Output ($/M tokens) | $50 | $25 |
Verdict. Claude Opus 5 (Adaptive Reasoning, Max 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 2.0× the per-million-token cost, Claude Opus 5 (Adaptive Reasoning, Max Effort) is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Claude Opus 5 (Adaptive Reasoning, Max Effort) makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) is strongest on Coding Index (76.5), Intelligence Index (62.1). Claude Opus 5 (Adaptive Reasoning, Max Effort) leads on Coding Index (78.0), Intelligence Index (63.1).
Speed. On throughput, Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) generates tokens at 67 tok/s versus 53 tok/s — about 21% faster. On time-to-first-token, Claude Opus 5 (Adaptive Reasoning, Max Effort) responds in 59970ms vs 148120ms, which matters most for chat-style UIs.
Provider. Both models come from the same vendor, so the choice comes down to which tier or generation fits your workload — not vendor lock-in.
Workload cost. Workload scenarios (per million requests at 30M input + 15M output tokens): Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) costs $1050.00 ($12600/year); Claude Opus 5 (Adaptive Reasoning, Max Effort) costs $525.00 ($6300/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) ≈ $150.00/run, Claude Opus 5 (Adaptive Reasoning, Max Effort) ≈ $75.00/run. At agent/realtime scale (200M input / 100M output per million requests): Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) ≈ $7000/run, Claude Opus 5 (Adaptive Reasoning, Max Effort) ≈ $3500/run. Claude Opus 5 (Adaptive Reasoning, Max 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, Max Effort) is cheaper overall. Its blended price (3:1 input/output ratio) is $10.00/M tokens vs $20.00/M for Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback).
Claude Opus 5 (Adaptive Reasoning, Max Effort) wins 2 out of 12 benchmarks compared to 0 for Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback). See the detailed benchmark chart above for per-category results.
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) generates tokens faster at 67 tok/s vs 53 tok/s. However, Claude Opus 5 (Adaptive Reasoning, Max Effort) has lower time-to-first-token (59.97s vs 148.12s).
Choose based on your priorities: Claude Opus 5 (Adaptive Reasoning, Max Effort) for lower cost, Claude Opus 5 (Adaptive Reasoning, Max Effort) for stronger benchmark performance, and Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) for faster generation. For latency-sensitive apps, check the TTFT comparison above.