Claude Fable 5.1 vs Claude Sonnet 4.5
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
Claude Fable 5.1 by Anthropic wins on 8 of 11 benchmarks against Claude Sonnet 4.5 by Anthropic, which leads on 2. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, Claude Fable 5.1 scores 53.4 on AA Intelligence Index compared to Claude Sonnet 4.5's 21.2.
Coding: In coding, Claude Fable 5.1 scores 81.6 on AA Coding Index compared to Claude Sonnet 4.5's 52.1, while Claude Fable 5.1 scores 1360 on Design Arena ELO compared to Claude Sonnet 4.5's 1184, while Claude Fable 5.1 scores 1322 on Website Arena ELO compared to Claude Sonnet 4.5's 1202.
Reasoning: In reasoning, Claude Fable 5.1 scores 90.0% on GPQA Diamond compared to Claude Sonnet 4.5's 82.5%, while Claude Fable 5.1 scores 58 on AA Agentic Index compared to Claude Sonnet 4.5's 17.5, while Claude Fable 5.1 scores 78.0% on τ²-Bench Airline compared to Claude Sonnet 4.5's 73.0%.
Context: In context, both score 1.0M on Context Length.
Pricing Comparison
Claude Fable 5.1 costs $10.0/1M input tokens and $50.0/1M output tokens, while Claude Sonnet 4.5 costs $3.0/1M input and $15.0/1M output. Claude Sonnet 4.5 is the more affordable option for API usage.
Verdict
Claude Sonnet 4.5 leads across the board in affordability, making it the stronger overall choice in this comparison.
View Individual Model Pages
Claude Fable 5.1 vs Claude Sonnet 4.5 — FAQ
Which is better, Claude Fable 5.1 or Claude Sonnet 4.5?
Claude Fable 5.1 wins on more benchmarks overall (8 vs 2). However, the best choice depends on your specific needs — each model excels in different areas.
How does Claude Fable 5.1 compare to Claude Sonnet 4.5 for coding?
SWE-bench Verified data is not available for both models. Check the detailed comparison charts above for other coding-related metrics.
Is Claude Fable 5.1 cheaper than Claude Sonnet 4.5?
Yes, Claude Sonnet 4.5 is cheaper. Claude Fable 5.1 costs $10.0/1M input and $50.0/1M output tokens. Claude Sonnet 4.5 costs $3.0/1M input and $15.0/1M output tokens.
Which is faster, Claude Fable 5.1 or Claude Sonnet 4.5?
Output speed data is not available for both models. Check the speed section of the comparison above for available performance data.
What benchmarks does the Claude Fable 5.1 vs Claude Sonnet 4.5 comparison cover?
This comparison covers 11 benchmarks including GPQA Diamond, Input Cost, Output Cost, Context Length, AA Intelligence Index, AA Coding Index, AA Agentic Index, Cached Input Cost, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.