Claude Fable 5 vs Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)
Wins 0 of 5 areas
—
Wins 2 of 5 areas
Agents · Reasoning
Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) wins more areas, narrowly.
Scores updated · 10 tests both models report · How we compare
Where each one wins
Tests won in each of the five areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- AgentsCarrying out multi-step tasks on its own02Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)2 of 2 tests
- ReasoningHard problems that need careful thinking01Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)1 of 2 tests · 1 tie
- CodingWriting and fixing software00Even0 each · 1 tie
- FactsGetting facts right instead of making them up11Even1 each
- Long documentsFinding answers in very long texts00Even0 each · 1 tie
Coding and long documents rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) costs 80% less for the same work.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) pulls ahead
- Complex command-line tasks across many fieldsTerminal-Bench 4.0+21.2points ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+16.6points ahead
- Real work tasks from 44 professionsGDPVal+11.4points ahead
Where Claude Fable 5 pulls ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+11.4points ahead
Every test, side by side
All 10 tests both models report. The winning score is in its model's colour; marks a score checked independently.
AgentsClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)
- Terminal-Bench 4.0Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) by 21.242.463.6+21.2
- GDPValClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) by 11.455.667+11.4
ReasoningClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)
- CritPtClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) by 2.828.631.4+2.8
- Humanity's Last Examtie55.555tie
FactsEven
- AA-Omniscience · Non-hallucinationClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) by 16.636.453+16.6
- AA-Omniscience · AccuracyClaude Fable 5 by 11.465.354+11.4
Other results2 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- AA-OmniscienceClaude Fable 5 by 1143.332.3+11
- AA IntelligenceClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) by 6.449.656+6.4
Questions people ask
Which is better, Claude Fable 5 or Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)?
Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) wins two of the five areas where both have results: agents and reasoning. Claude Fable 5 wins none. They are level on coding, facts and long documents.
Which is better for coding?
Neither. All 1 coding tests both models report are ties.
Which is cheaper?
Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) costs $2.00 and $10.00. That makes Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) about 80% cheaper for the same work.
How do you compare the two?
We use the 10 benchmark tests both models have published scores on. The verdict counts the 8 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 2 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.