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Claude Sonnet 5.5 vs GPT-5.6 Terra

Claude Sonnet 5.5 leads GPT-5.6 Terra on coding, 87.3 to 63.9 on the Vibe Coding Index, and Claude Sonnet 5.5 costs 1.2x less per output token ($10.00 vs $12.00 per million). Updated October 22, 2026; 87 benchmarks have a result for both.

Replace Claude Sonnet 5.5 Replace GPT-5.6 Terra
Claude Sonnet 5.5Anthropic
Coding
87.3
Overall
82.8
Output $/M
$10.00
80
GPT-5.6 TerraOpenAI
Coding
63.9
Overall
68.1
Output $/M
$12.00
6
vs boards won of 87 shared, 1 tied

Claude Sonnet 5.5 or GPT-5.6 Terra: which to pick

Pick Claude Sonnet 5.5 for coding: it scores 87.3 on the Vibe Coding Index against 63.9 for GPT-5.6 Terra, though on 5 benchmarks against 6.

Pick GPT-5.6 Terra for a larger context window (1.05M against 1M tokens) and work measured by IOI (Vals AI) or CyberBench (Vals AI), where it leads.

Model AClaude Sonnet 5.5Anthropic87.3/1005 independent benchmarksNo cost per solved taskModel BGPT-5.6 TerraOpenAI63.9/1006 independent benchmarks$0.42 per solved task
Shared results
87
Claude Sonnet 5.5 only
9
GPT-5.6 Terra only
40
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Sonnet 5.5 87.3 from 5 benchmarks, GPT-5.6 Terra 63.9 from 6 benchmarks.
Widest category
Web design, 19.1 points apart on average over 7 shared benchmarks.
Widest single gap
Terminal-Bench 4 (Vals AI): Claude Sonnet 5.5 64.1% against GPT-5.6 Terra 22.7%, 55.2 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 5.5 $10.00 against GPT-5.6 Terra $12.00 per million output tokens, 1.2x apart.
Context window
Claude Sonnet 5.5 takes 1M tokens, GPT-5.6 Terra 1.05M.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Sonnet 5.5BarsGPT-5.6 TerraTies
Coding153
Intelligence20
Agentic work1201 tie
Reasoning100
Math60
Knowledge60
Web design70
General223
All shared boards8061 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index153
Coding benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
LiveBench coding94.7%86.2%Claude Sonnet 5.5
LMArena WebDev17681522Claude Sonnet 5.5
AA Coding IndexNot measured76.7Only GPT-5.6 Terra measured
LiveCodeBench (Vals AI)Not measured85.9%Only GPT-5.6 Terra measured
SWE-bench Verified (Vals AI)Not measured95.4%Only GPT-5.6 Terra measured
Terminal-Bench 4 (Vals AI)64.1%22.7%Claude Sonnet 5.5
Vibe Code Bench (Vals AI)92.4%74.6%Claude Sonnet 5.5
Code migration (Vals AI)69.8%47.8%Claude Sonnet 5.5
ProgramBench (Vals AI)6.5%0.5%Claude Sonnet 5.5
IOI (Vals AI)83.1%87.6%GPT-5.6 Terra
Terminal-Bench 2.1 (Vals AI)83.2%77.5%Claude Sonnet 5.5
SWE-bench Multimodal (Vals AI)58.3%Not measuredOnly Claude Sonnet 5.5 measured
Vibe Code Bench 1-100 (Vals AI)Not measured14.8%Only GPT-5.6 Terra measured
SkillsBench (Vals AI)Not measured58.9%Only GPT-5.6 Terra measured
CyberBench (Vals AI)59.6%72.1%GPT-5.6 Terra
SciCode61.0%55.0%Claude Sonnet 5.5
Terminal-Bench Hard (Artificial Analysis run)Not measured62.9%Only GPT-5.6 Terra measured
FrontierCode52.1%41.3%Claude Sonnet 5.5
FrontierSWE61.9%Not measuredOnly Claude Sonnet 5.5 measured
WeirdMLNot measured78.3%Only GPT-5.6 Terra measured
ALE-Bench1819.11951.4GPT-5.6 Terra
LMArena Text: coding15131485Claude Sonnet 5.5
LMArena Text: software and IT15041482Claude Sonnet 5.5
LMArena WebDev: React18171513Claude Sonnet 5.5
LMArena WebDev: HTML17411526Claude Sonnet 5.5
LMArena WebDev: from an image17371541Claude Sonnet 5.5
SciCode13.8%10.8%Claude Sonnet 5.5
Neither model has a result on the other 12 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
AA Intelligence Index56.042.1Claude Sonnet 5.5
Epoch Capabilities Index166.2160.1Claude Sonnet 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index120
Agentic work benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
AA Agentic IndexNot measured43.2Only GPT-5.6 Terra measured
Design Arena: agents building web apps13051120Claude Sonnet 5.5
Design Arena: agents building full-stack appsNot measured1061Only GPT-5.6 Terra measured
Design Arena: agents building mobile apps12601111Claude Sonnet 5.5
Design Arena: agents building Android appsNot measured1062Only GPT-5.6 Terra measured
Design Arena: agents building gamesNot measured1083Only GPT-5.6 Terra measured
Design Arena: HTML slidesNot measured1058Only GPT-5.6 Terra measured
Design Arena: PowerPoint slidesNot measured1105Only GPT-5.6 Terra measured
Design Arena: spreadsheets1260Not measuredOnly Claude Sonnet 5.5 measured
LiveBench research83.6%60.4%Claude Sonnet 5.5
LiveBench browser84.0%84.0%Tie
LiveBench long agentic78.8%48.4%Claude Sonnet 5.5
SREBench (Vals AI)30.1%9.5%Claude Sonnet 5.5
Finance Agent (Vals AI)58.1%54.4%Claude Sonnet 5.5
Tax Agent Bench (Vals AI)42.0%30.0%Claude Sonnet 5.5
Legal Research Bench (Vals AI)48.1%41.4%Claude Sonnet 5.5
Harvey's Legal Agent Benchmark (Vals AI)10.4%Not measuredOnly Claude Sonnet 5.5 measured
Excel Modeling Benchmark (Vals AI)75.7%66.2%Claude Sonnet 5.5
BioMysteryBench (Vals AI)81.1%Not measuredOnly Claude Sonnet 5.5 measured
Terminal-Bench-Science (Vals AI)47.1%10.0%Claude Sonnet 5.5
Vals Science Index59.1%Not measuredOnly Claude Sonnet 5.5 measured
τ²-Bench TelecomNot measured86.3%Only GPT-5.6 Terra measured
APEX-Agents75.5%58.2%Claude Sonnet 5.5
BALROGNot measured53.2%Only GPT-5.6 Terra measured
SpireClimb1.3%Not measuredOnly Claude Sonnet 5.5 measured
Vending-Bench 2$11,165$7,343Claude Sonnet 5.5
Neither model has a result on the other 15 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index100
Reasoning benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
GPQA DiamondNot measured90.9%Only GPT-5.6 Terra measured
LiveBench reasoning91.6%90.6%Claude Sonnet 5.5
MysteryMechanism (Vals AI)49.1%Not measuredOnly Claude Sonnet 5.5 measured
MMMU Pro (Vals AI)Not measured86.5%Only GPT-5.6 Terra measured
GPQA Diamond (Artificial Analysis run)Not measured92.5%Only GPT-5.6 Terra measured
Humanity's Last Exam (Artificial Analysis run)55.0%42.9%Claude Sonnet 5.5
GPQA Diamond (Epoch AI run)95.6%93.3%Claude Sonnet 5.5
ARC-AGINot measured96.5%Only GPT-5.6 Terra measured
ARC-AGI-2Not measured83.9%Only GPT-5.6 Terra measured
SimpleBenchNot measured48.9%Only GPT-5.6 Terra measured
Chess puzzles59.0%47.0%Claude Sonnet 5.5
Mystery game puzzles65.0%35.0%Claude Sonnet 5.5
LMArena Text: hard prompts14941469Claude Sonnet 5.5
LMArena Text: expert15311496Claude Sonnet 5.5
LMArena Text: hard prompts in English15021465Claude Sonnet 5.5
LMArena Vision: diagrams13291295Claude Sonnet 5.5
LMArena Vision: homework13311312Claude Sonnet 5.5
Kagi LLM BenchmarkNot measured51.3%Only GPT-5.6 Terra measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
OTIS Mock AIME100.0%99.7%Claude Sonnet 5.5
FrontierMath, tiers 1 to 388.8%86.0%Claude Sonnet 5.5
FrontierMath, tier 480.5%70.7%Claude Sonnet 5.5
ProofBench100.0%74.0%Claude Sonnet 5.5
LMArena Text: math14971465Claude Sonnet 5.5
LMArena Text: mathematical work15101478Claude Sonnet 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
Knowledge benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
MMLU ProNot measured86.7%Only GPT-5.6 Terra measured
LegalBench (Vals AI)Not measured85.1%Only GPT-5.6 Terra measured
CorpFin (Vals AI)Not measured65.3%Only GPT-5.6 Terra measured
TaxEval (Vals AI)Not measured76.2%Only GPT-5.6 Terra measured
MortgageTax (Vals AI)Not measured67.3%Only GPT-5.6 Terra measured
MedCode (Vals AI)52.9%43.4%Claude Sonnet 5.5
SimpleQA Verified46.5%43.2%Claude Sonnet 5.5
LMArena Text: science14831452Claude Sonnet 5.5
LMArena Text: medicine and healthcare14641430Claude Sonnet 5.5
LMArena Text: legal and government14831461Claude Sonnet 5.5
LMArena Text: business and finance14681448Claude Sonnet 5.5
FACTS Benchmark SuiteNot measured52.0%Only GPT-5.6 Terra measured
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index70
Web design benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
Design Arena: websites13261268Claude Sonnet 5.5
Design Arena: UI components13681256Claude Sonnet 5.5
Design Arena: game dev14711229Claude Sonnet 5.5
Design Arena: data viz13921240Claude Sonnet 5.5
Design Arena: 3D14451134Claude Sonnet 5.5
Design Arena: all code categories13641241Claude Sonnet 5.5
Design Arena: SVGNot measured1219Only GPT-5.6 Terra measured
Design Arena: ASCII artNot measured1177Only GPT-5.6 Terra measured
LiveBench design85.0%76.0%Claude Sonnet 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index223
General benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
Vals Index70.8%Not measuredOnly Claude Sonnet 5.5 measured
LiveBench data analysis59.5%79.3%GPT-5.6 Terra
Public Benefits Bench (Vals AI)67.2%62.4%Claude Sonnet 5.5
SAGE (Vals AI)51.8%47.0%Claude Sonnet 5.5
MedScribe (Vals AI)91.1%82.9%Claude Sonnet 5.5
Vals Multimodal IndexNot measured65.1%Only GPT-5.6 Terra measured
IFBenchNot measured71.2%Only GPT-5.6 Terra measured
Long context reasoning (AA-LCR)82.7%83.0%GPT-5.6 Terra
DTBench97.3%93.3%Claude Sonnet 5.5
LMCA68.3%54.9%Claude Sonnet 5.5
Surface Evolver BenchNot measured83.8%Only GPT-5.6 Terra measured
Furniture assembly75.0%54.2%Claude Sonnet 5.5
LMArena Text14731448Claude Sonnet 5.5
LMArena Text: instruction following14921456Claude Sonnet 5.5
LMArena Text: creative writing14671413Claude Sonnet 5.5
LMArena Vision12871271Claude Sonnet 5.5
LMArena Text: English14841449Claude Sonnet 5.5
LMArena Text: non-English14561441Claude Sonnet 5.5
LMArena Text: Chinese15351514Claude Sonnet 5.5
LMArena Text: GermanNot measured1460Only GPT-5.6 Terra measured
LMArena Text: JapaneseNot measured1454Only GPT-5.6 Terra measured
LMArena Text: KoreanNot measured1427Only GPT-5.6 Terra measured
LMArena Text: French14991466Claude Sonnet 5.5
LMArena Text: Spanish14511451Claude Sonnet 5.5
LMArena Text: Russian14541452Claude Sonnet 5.5
LMArena Text: PolishNot measured1446Only GPT-5.6 Terra measured
LMArena Text: multi-turn14651453Claude Sonnet 5.5
LMArena Text: longer queries14951454Claude Sonnet 5.5
LMArena Text: writing and language14741431Claude Sonnet 5.5
LMArena Text: entertainment and media14611418Claude Sonnet 5.5
LMArena Vision: English12891272Claude Sonnet 5.5
LMArena Vision: ChineseNot measured1337Only GPT-5.6 Terra measured
LMArena Vision: reading text12971278Claude Sonnet 5.5
LMArena Vision: humorNot measured1236Only GPT-5.6 Terra measured
LMArena Vision: creative writing12421248GPT-5.6 Terra
LMArena DocumentNot measured1472Only GPT-5.6 Terra measured
Neither model has a result on the other 10 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Sonnet 5.5 and GPT-5.6 Terra
BenchmarkClaude Sonnet 5.5GPT-5.6 TerraLeader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Sonnet 5.5$0.0070Fits in one request
GPT-5.6 Terra$0.0080Fits in one request

Claude Sonnet 5.5 costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 5.5$0.130Fits in one request
GPT-5.6 Terra$0.136Fits in one request

Claude Sonnet 5.5 costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 5.5$0.500Fits in one request
GPT-5.6 Terra$0.520Fits in one request

Claude Sonnet 5.5 costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Sonnet 5.5 and GPT-5.6 Terra
SpecificationAnthropic Claude Sonnet 5.5OpenAI GPT-5.6 Terra
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 28, 2026July 9, 2026
Context window1M1.05M
Input $/Mtok$2.00$2.00
Output $/Mtok$10.00$12.00
Coding index87.363.9
Independent measurements behind it56
Cost per solved taskNot computable$0.42
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 5.5 better than GPT-5.6 Terra for coding?

Pick Claude Sonnet 5.5 for coding: it scores 87.3 on the Vibe Coding Index against 63.9 for GPT-5.6 Terra, though on 5 benchmarks against 6. Pick GPT-5.6 Terra for a larger context window (1.05M against 1M tokens) and work measured by IOI (Vals AI) or CyberBench (Vals AI), where it leads.

Which is cheaper, Claude Sonnet 5.5 or GPT-5.6 Terra?

Claude Sonnet 5.5 costs $2.00 per million input tokens and $10.00 per million output tokens; GPT-5.6 Terra costs $2.00 and $12.00. Cost per solved task is known for GPT-5.6 Terra only.

Which has the bigger context window, Claude Sonnet 5.5 or GPT-5.6 Terra?

GPT-5.6 Terra, with 1.05M tokens against 1M.

How many benchmarks is the Claude Sonnet 5.5 vs GPT-5.6 Terra comparison based on?

87 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 5.5's coding index rests on 5 independent benchmarks and GPT-5.6 Terra's on 6. Where only one model has a result, the page says so instead of naming a winner.

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