Claude Opus 5.5 vs Claude Fable 5.1
How does Claude Opus 5.5 (Anthropic) compare against Claude Fable 5.1 (Anthropic)? Side-by-side scores, capability ratings and pricing, plus a clear verdict.
🏆 Quick verdict
Claude Opus 5.5 comes out ahead with an AIVerso score of 99 vs 99 and an aggregate capability rating of 667 vs 662 across 7 categories. Claude Fable 5.1 still leads on Long Context.
Overall winner
Claude Opus 5.5
by Anthropic
Score: 99/100
PriceFrom $20/mo (Pro)
Pricing details$4/$20 per 1M
Context window1M
Free tierNo
API accessYes
Open sourceNo
Headline factsFable-class coding for less · #1 SWE-bench Pro (89.9%) · #1 Terminal-Bench 4.0 (66.4%) · $4/$20 per 1M · 1M context
🔗 Try Claude Opus 5.5 →
Full Claude Opus 5.5 profile →
Claude Fable 5.1
by Anthropic
Score: 99/100
Price$10/$50 per 1M tokens
Context window1M
Free tierNo
API accessYes
Open sourceNo
Headline factsAnthropic's most capable model overall · doubles Terminal-Bench (52.6%) · always-on adaptive thinking · SWE-bench Pro 81.2%
🔗 Try Claude Fable 5.1 →
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📊 Capability ratings
AIVerso capability ratings (0–100) per category — an editorial summary informed by public benchmark results. Higher is better.
Category
Claude Opus 5.5
Claude Fable 5.1
Math & Logice.g. AIME, MATH-500
96
96
Programminge.g. SWE-bench, LiveCodeBench
96
95
Reasoninge.g. GPQA, ARC
96
94
Knowledgee.g. MMLU-Pro
92
91
Long Contexte.g. MRCR, needle tests
95
96
Instruction Followinge.g. IFEval
95
95
Agent Capabilitye.g. Terminal-Bench, tool use
97
95
Why Claude Opus 5.5
Lower API price ($4/$20 per 1M vs $10/$50 per 1M tokens)
Leads on Programming (96 vs 95)
Leads on Reasoning (96 vs 94)
Leads on Knowledge (92 vs 91)
Leads on Agent Capability (97 vs 95)
Fable-class coding for less
#1 SWE-bench Pro (89.9%)
Why Claude Fable 5.1
Leads on Long Context (96 vs 95)
Anthropic's most capable model overall
doubles Terminal-Bench (52.6%)
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❓ Frequently Asked Questions
Which is better: Claude Opus 5.5 or Claude Fable 5.1?
Claude Opus 5.5 has the higher AIVerso score (99 vs 99). The better choice still depends on your use case — Claude Fable 5.1 leads on Long Context.
How much does Claude Opus 5.5 cost compared to Claude Fable 5.1?
Claude Opus 5.5: From $20/mo (Pro) ($4/$20 per 1M). Claude Fable 5.1: $10/$50 per 1M tokens. Neither has a free tier.
What context window does each support?
Claude Opus 5.5: 1M tokens. Claude Fable 5.1: 1M tokens. The context window determines how much text, code or chat history a model can process at once.
Are Claude Opus 5.5 and Claude Fable 5.1 open source?
Claude Opus 5.5 is a closed, proprietary model. Claude Fable 5.1 is a closed, proprietary model.
How we compare: Scores and capability ratings are based on public benchmarks and provider documentation — not on commission rates. Last updated: September 29, 2026.