Claude Fable 5 vs Sonnet 5.5
Wins 3 of 6 areas
Facts · Images and charts · Following instructions
Wins 2 of 6 areas
Coding · Reasoning
Claude Fable 5 wins more areas, narrowly.Sonnet 5.5 is cheaper and better at coding.
Both rank among the ten best models we track in math.
Scores updated · 29 tests both models report · How we compare
Where each one wins
Tests won in each of the six 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.
- FactsGetting facts right instead of making them up10Claude Fable 51 of 1 test
- Images and chartsUnderstanding pictures, charts and video10Claude Fable 51 of 1 test
- Following instructionsDoing exactly what it is asked10Claude Fable 51 of 1 test
- CodingWriting and fixing software14Sonnet 5.54 of 5 tests
- ReasoningHard problems that need careful thinking12Sonnet 5.52 of 3 tests
- MathCompetition and research-level math11Even1 each · 1 tie
Facts, images and charts and following instructions 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.
Sonnet 5.5 costs 80% less for the same work.
The biggest differences
The three tests each model wins by the widest margin. Scores are out of 100.
Where Claude Fable 5 pulls ahead
- Short factual questions, answered correctlySimpleQA Verified+24.2points ahead
- Follows detailed instructions exactlyLiveBench · Instruction Following+19points ahead
- Extremely hard research-level math problemsFrontierMath Tier 4+9.7points ahead
Where Sonnet 5.5 pulls ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+9points ahead
- Programming problems, refreshed regularlyLiveBench · Coding+5.4points ahead
- Fixes real GitHub issues in many programming languagesSWE-bench Multilingual+3.7points ahead
Every test, side by side
All 29 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingSonnet 5.5
- LMArena · WebDevSonnet 5.5 by 161 rating points16251786+161 rating
- LiveBench · Agentic CodingClaude Fable 5 by 5.962.256.3+5.9
- LiveBench · CodingSonnet 5.5 by 5.48691.4+5.4
- SWE-bench MultilingualSonnet 5.5 by 3.786.690.3+3.7
- SWE-bench ProSonnet 5.5 by 1.38081.3+1.3
ReasoningSonnet 5.5
- Humanity's Last ExamSonnet 5.5 by 955.564.5+9
- SimpleBenchClaude Fable 5 by 681.975.9+6
- LiveBench · ReasoningSonnet 5.5 by 1.989.791.6+1.9
Images and chartsClaude Fable 5
- LMArena · VisionClaude Fable 5 by 35 rating points13251290+35 rating
MathEven
- FrontierMath Tier 4Claude Fable 5 by 9.790.280.5+9.7
- FrontierMath Tiers 1-3 (v2)Sonnet 5.5 by 1.88788.8+1.8
- LiveBench · Mathematicstie9696.1tie
Following instructionsClaude Fable 5
- LiveBench · Instruction FollowingClaude Fable 5 by 1975.856.8+19
Other results15 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.
- Terminal-Bench-Science 0.1Sonnet 5.5 by 35.224.759.9+35.2
- Terminal-Bench 4.0Sonnet 5.5 by 26.144.570.6+26.1
- GDPval-AA 2.1Sonnet 5.5 by 245 rating points15951840+245 rating
- livebench_data_analysisClaude Fable 5 by 2180.559.5+21
- livebench_languageClaude Fable 5 by 12.790.778+12.7
- OfficeQA ProSonnet 5.5 by 7.757.965.6+7.7
- Program BenchClaude Fable 5 by 6.686.379.7+6.6
- AA IntelligenceSonnet 5.5 by 6.449.656+6.4
- HealthBench ProfessionalSonnet 5.5 by 3.26669.2+3.2
- Legal Agent BenchmarkClaude Fable 5 by 1.613.311.7+1.6
- MILUClaude Fable 5 by 1.392.991.6+1.3
- DeepSWE 1.1Sonnet 5.5 by 17071+1
- HLE (with tools)tie63.864.5tie
- SWE-bench Multimodaltie54.154.3tie
- Toolathlon Verifiedtie77.977.8tie
Questions people ask
Which is better, Claude Fable 5 or Sonnet 5.5?
Claude Fable 5 wins three of the six areas where both have results: facts, images and charts and following instructions. Sonnet 5.5 wins coding and reasoning, and costs 80% less. They are level on math.
Which is better for coding?
Sonnet 5.5. It wins 4 of the 5 coding tests both models report; Claude Fable 5 wins 1.
Which is cheaper?
Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; Sonnet 5.5 costs $2.00 and $10.00. That makes Sonnet 5.5 about 80% cheaper for the same work.
How do you compare the two?
We use the 29 benchmark tests both models have published scores on. The verdict counts the 14 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 15 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.