Claude Opus 5 vs Sonnet 5.5
Wins 3 of 6 areas
Facts · Images and charts · Following instructions
Wins 2 of 6 areas
Coding · Math
Claude Opus 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 · 32 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 Opus 51 of 1 test
- Images and chartsUnderstanding pictures, charts and video10Claude Opus 51 of 1 test
- Following instructionsDoing exactly what it is asked10Claude Opus 51 of 1 test
- CodingWriting and fixing software13Sonnet 5.53 of 5 tests · 1 tie
- MathCompetition and research-level math02Sonnet 5.52 of 3 tests · 1 tie
- ReasoningHard problems that need careful thinking11Even1 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 60% 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 Opus 5 pulls ahead
- Short factual questions, answered correctlySimpleQA Verified+13.4points ahead
- Fixes real GitHub issues, working as an agentLiveBench · Agentic Coding+8.9points ahead
- Follows detailed instructions exactlyLiveBench · Instruction Following+7points ahead
Where Sonnet 5.5 pulls ahead
- Programming problems, refreshed regularlyLiveBench · Coding+9.9points ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+9.6points ahead
- Extremely hard research-level math problemsFrontierMath Tier 4+7.3points ahead
Every test, side by side
All 32 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingSonnet 5.5
- LiveBench · CodingSonnet 5.5 by 9.981.591.4+9.9
- LMArena · WebDevSonnet 5.5 by 91 rating points16951786+91 rating
- LiveBench · Agentic CodingClaude Opus 5 by 8.965.256.3+8.9
- SWE-bench ProSonnet 5.5 by 2.179.281.3+2.1
- SWE-bench Multilingualtie89.590.3tie
ReasoningEven
- Humanity's Last ExamSonnet 5.5 by 9.654.964.5+9.6
- SimpleBenchClaude Opus 5 by 4.780.675.9+4.7
- LiveBench · Reasoningtie91.291.6tie
Images and chartsClaude Opus 5
- LMArena · VisionClaude Opus 5 by 31 rating points13211290+31 rating
MathSonnet 5.5
- FrontierMath Tier 4Sonnet 5.5 by 7.373.280.5+7.3
- FrontierMath Tiers 1-3 (v2)Sonnet 5.5 by 3.285.688.8+3.2
- LiveBench · Mathematicstie95.796.1tie
Following instructionsClaude Opus 5
- LiveBench · Instruction FollowingClaude Opus 5 by 763.856.8+7
Other results18 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 30.92959.9+30.9
- Terminal-Bench 4.0Sonnet 5.5 by 18.851.870.6+18.8
- livebench_data_analysisClaude Opus 5 by 15.174.559.5+15.1
- GDPval-AA 2.1Sonnet 5.5 by 132 rating points17081840+132 rating
- livebench_languageClaude Opus 5 by 10.788.778+10.7
- HealthBench ProfessionalSonnet 5.5 by 9.459.869.2+9.4
- HealthBench Professional length-adjustedSonnet 5.5 by 9.459.869.2+9.4
- OSWorld 2.1 partialSonnet 5.5 by 6.17480.1+6.1
- Program BenchClaude Opus 5 by 5.785.479.7+5.7
- AA IntelligenceSonnet 5.5 by 5.250.856+5.2
- SWE-bench MultimodalClaude Opus 5 by 5.159.454.3+5.1
- Toolathlon VerifiedClaude Opus 5 by 2.880.677.8+2.8
- DeepSWE 1.1Sonnet 5.5 by 2.268.871+2.2
- OfficeQA ProClaude Opus 5 by 1.366.965.6+1.3
- OfficeQAClaude Opus 5 by 1.278.176.9+1.2
- HLE (with tools)tie63.664.5tie
- MILUtie92.191.6tie
- Legal Agent Benchmarktie11.711.7tie
Questions people ask
Which is better, Claude Opus 5 or Sonnet 5.5?
Claude Opus 5 wins three of the six areas where both have results: facts, images and charts and following instructions. Sonnet 5.5 wins coding and math, and costs 60% less. They are level on reasoning.
Which is better for coding?
Sonnet 5.5. It wins 3 of the 5 coding tests both models report; Claude Opus 5 wins 1, and 1 is a tie.
Which is cheaper?
Claude Opus 5 costs $5.00 per million input tokens and $25.00 per million output tokens; Sonnet 5.5 costs $2.00 and $10.00. That makes Sonnet 5.5 about 60% cheaper for the same work.
How do you compare the two?
We use the 32 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 18 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.