Claude 5.5 vs Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback)
Wins 3 of 5 areas
Coding · Agents · Reasoning
Wins 1 of 5 areas
Facts
Claude 5.5 is the stronger all-rounder.Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback) is better at facts.
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 own20Claude 5.52 of 2 tests
- ReasoningHard problems that need careful thinking20Claude 5.52 of 2 tests
- CodingWriting and fixing software10Claude 5.51 of 1 test
- FactsGetting facts right instead of making them up01Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback)1 of 2 tests · 1 tie
- 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.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude 5.5 pulls ahead
Where Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback) pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+1points 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 5.5
- Terminal-Bench 4.0Claude 5.5 by 9.129.820.7+9.1
- GDPValClaude 5.5 by 7.341.233.9+7.3
ReasoningClaude 5.5
- CritPtClaude 5.5 by 5.516.911.4+5.5
- Humanity's Last ExamClaude 5.5 by 3.639.836.2+3.6
FactsClaude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback)
- AA-Omniscience · Non-hallucinationClaude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback) by 148.849.8+1
- AA-Omniscience · Accuracytie47.246.3tie
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 IntelligenceClaude 5.5 by 4.940.835.9+4.9
- AA-Omnisciencetie20.119.4tie
Questions people ask
Which is better, Claude 5.5 or Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback)?
Claude 5.5 wins three of the five areas where both have results: coding, agents and reasoning. Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback) wins facts. They are level on long documents.
Which is better for coding?
Claude 5.5. It wins the one coding test both models report.
Which is cheaper?
Claude 5.5 costs $2.00 per million input tokens and $10.00 per million output tokens; Claude Sonnet 5.5 (Adaptive Reasoning, Low Effort, Default Fallback) costs $2.00 and $10.00. For a million tokens read plus a million written, they cost about the same.
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.