Objective comparison based on public benchmarks updated weekly: Intelligence Index, Chatbot Arena ELO, pricing and speed.
Overall winner (2026)
Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)
4 of 6 criteria won
Anthropic
Intelligence Index
57.6
4 criteria won
View full profile →Anthropic
ELO Arena
1501
Intelligence Index
53.4
Coding Index
81.6
2 criteria won
View full profile →| Critério | Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) | Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) |
|---|---|---|
| Chatbot Arena ELO | — | 1501 ✓ |
| Intelligence Index (AA) | 57.6 ✓ | 53.4 |
| Coding Index (AA) | — | 81.6 ✓ |
| Input price ($/1M tok) | $4.00 ✓ | $10.00 |
| Output price ($/1M tok) | $20.00 ✓ | $50.00 |
| Context window | 1.0M tokens | 1.0M tokens |
| Speed (tokens/s) | 92 tok/s ✓ | 68 tok/s |
✓ = winner in this criterion • Source: Artificial Analysis, LMArena, official APIs • Updated weekly
Choosing between Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) and Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) depends on your use case, budget and technical requirements. Below, a practical guide based on benchmark data and each model's specifications.
Anthropic · Text
Anthropic · Text
Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) wins in 4 of 6 criteria analyzed. Check the full table to choose based on your use case.
Data is aggregated from Artificial Analysis (Intelligence Index, Coding Index) and Chatbot Arena/LMArena (ELO). Pricing and specs come from official APIs. Updated weekly.
The Intelligence Index is an aggregate score from Artificial Analysis that combines multiple academic benchmarks (MMLU, GPQA, LiveBench, etc.) into a single rating. The higher the score, the more capable the model is at reasoning tasks.
Yes. Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) costs $4/1M input tokens, while Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) costs $10/1M tokens — 150% more expensive. For high-volume projects, Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) represents significant savings. Total cost also depends on output pricing and your application's usage pattern.
Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) and Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) have the same context window: 1.0M tokens. For this criterion, the choice should be based on other factors like pricing and quality for your specific use case.