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Claude Sonnet 4.5 vs GPT-5.1

GPT-5.1 leads Claude Sonnet 4.5 on coding, 40.4 to 39.5 on the Vibe Coding Index, and GPT-5.1 costs 1.5x less per output token ($10.00 vs $15.00 per million). Updated October 22, 2026; 78 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace GPT-5.1
Claude Sonnet 4.5Anthropic
Coding
39.5
Overall
49.5
Output $/M
$15.00
35
GPT-5.1OpenAI
Coding
40.4
Overall
55.0
Output $/M
$10.00
43
vs boards won of 78 shared

Claude Sonnet 4.5 or GPT-5.1: which to pick

Claude Sonnet 4.5 and GPT-5.1 are level for coding, 39.5 against 40.4 on the Vibe Coding Index, so price and context decide.

Pick Claude Sonnet 4.5 for a larger context window (1M against 400K tokens) and work measured by SWE-bench Verified or AA Coding Index, where it leads. Pick GPT-5.1 for output tokens 1.5x cheaper ($10.00 vs $15.00 per million) and a lower cost per solved task ($1.02 against $1.16).

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved taskModel BGPT-5.1OpenAI40.4/1003 independent benchmarks$1.02 per solved task
Shared results
78
Claude Sonnet 4.5 only
17
GPT-5.1 only
23
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 4.5 39.5 from 3 benchmarks, GPT-5.1 40.4 from 3 benchmarks.
Widest category
Agentic work, 12.3 points apart on average over 2 shared benchmarks.
Widest single gap
Chess puzzles: Claude Sonnet 4.5 10.0% against GPT-5.1 42.0%, 32.0 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 4.5 $15.00 against GPT-5.1 $10.00 per million output tokens, 1.5x apart.
Context window
Claude Sonnet 4.5 takes 1M tokens, GPT-5.1 400K.

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 4.5BarsGPT-5.1Ties
Coding76
Intelligence02
Agentic work20
Reasoning48
Math32
Knowledge311
Web design53
General1111
All shared boards3543
CodingLike-for-likeSix of these boards feed the Vibe Coding Index76
Coding benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
SWE-bench Verified74.8%66.0%Claude Sonnet 4.5
SWE-bench Multilingual67.0%Not measuredOnly Claude Sonnet 4.5 measured
LMArena WebDev13941396GPT-5.1
AA Coding Index52.149.4Claude Sonnet 4.5
LiveCodeBench (Vals AI)73.0%86.5%GPT-5.1
SWE-bench Verified (Vals AI)70.0%69.8%Claude Sonnet 4.5
Vibe Code Bench (Vals AI)22.6%24.6%GPT-5.1
LiveCodeBench (Artificial Analysis run)Not measured86.8%Only GPT-5.1 measured
Terminal-Bench Hard (Artificial Analysis run)Not measured45.5%Only GPT-5.1 measured
Terminal-Bench46.5%47.6%GPT-5.1
GSO-Bench14.7%13.7%Claude Sonnet 4.5
WeirdML47.7%60.8%GPT-5.1
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: coding14881453Claude Sonnet 4.5
LMArena Text: software and IT14731454Claude Sonnet 4.5
LMArena WebDev: React13861307Claude Sonnet 4.5
LMArena WebDev: HTML13991405GPT-5.1
LMArena WebDev: from an imageNot measured1421Only GPT-5.1 measured
Neither model has a result on the other 21 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
AA Intelligence Index20.724.7GPT-5.1
Epoch Capabilities Index146.7149.8GPT-5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index20
Agentic work benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
AA Agentic Index15.8Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building web apps1060Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building full-stack apps1050Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building mobile apps1137Not measuredOnly Claude Sonnet 4.5 measured
τ²-Bench TelecomNot measured81.9%Only GPT-5.1 measured
METR time horizons67.4%Not measuredOnly Claude Sonnet 4.5 measured
Remote Labor Index2.1%Not measuredOnly Claude Sonnet 4.5 measured
GDPval42.5%Not measuredOnly Claude Sonnet 4.5 measured
DeepResearch Bench52.6%42.8%Claude Sonnet 4.5
OSWorld62.9%Not measuredOnly Claude Sonnet 4.5 measured
Vending-Bench 2$3,839$1,473Claude Sonnet 4.5
Berkeley Function Calling Leaderboard (BFCL)73.2%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 29 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index48
Reasoning benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
GPQA Diamond81.6%86.6%GPT-5.1
MMMU Pro (Vals AI)79.3%83.2%GPT-5.1
GPQA Diamond (Artificial Analysis run)Not measured87.3%Only GPT-5.1 measured
Humanity's Last Exam (Artificial Analysis run)Not measured28.5%Only GPT-5.1 measured
GPQA Diamond (Epoch AI run)82.3%87.6%GPT-5.1
ARC-AGI63.7%72.8%GPT-5.1
ARC-AGI-213.6%17.6%GPT-5.1
SimpleBench54.3%53.2%Claude Sonnet 4.5
Chess puzzles10.0%42.0%GPT-5.1
Mystery game puzzles17.0%19.0%GPT-5.1
EBR-bench2.4%Not measuredOnly Claude Sonnet 4.5 measured
VPCT39.8%58.7%GPT-5.1
LMArena Text: hard prompts14621457Claude Sonnet 4.5
LMArena Text: expert14831470Claude Sonnet 4.5
LMArena Text: hard prompts in English14711462Claude Sonnet 4.5
LMArena Vision: diagramsNot measured1264Only GPT-5.1 measured
LMArena Vision: homeworkNot measured1272Only GPT-5.1 measured
Kagi LLM Benchmark57.9%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index32
Math benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
AIME88.2%93.3%GPT-5.1
MGSM (Vals AI)94.3%93.0%Claude Sonnet 4.5
AA Math IndexNot measured94.0Only GPT-5.1 measured
AIME 2025 (Artificial Analysis run)Not measured94.0%Only GPT-5.1 measured
OTIS Mock AIME77.8%88.6%GPT-5.1
FrontierMath, tiers 1 to 323.9%Not measuredOnly Claude Sonnet 4.5 measured
FrontierMath, tier 42.4%Not measuredOnly Claude Sonnet 4.5 measured
ProofBench19.0%Not measuredOnly Claude Sonnet 4.5 measured
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491446Claude Sonnet 4.5
LMArena Text: mathematical work14621449Claude Sonnet 4.5
Neither model has a result on the other 2 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index311
Knowledge benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
MMLU Pro87.4%86.4%Claude Sonnet 4.5
LegalBench (Vals AI)84.1%85.7%GPT-5.1
CaseLaw (Vals AI)62.2%73.4%GPT-5.1
CorpFin (Vals AI)62.0%63.8%GPT-5.1
TaxEval (Vals AI)73.3%74.9%GPT-5.1
MortgageTax (Vals AI)64.0%61.4%Claude Sonnet 4.5
MedQA (Vals AI)94.7%96.4%GPT-5.1
MedCode (Vals AI)44.1%52.7%GPT-5.1
MMLU Pro (Artificial Analysis run)Not measured87.0%Only GPT-5.1 measured
SimpleQA Verified30.7%48.0%GPT-5.1
LMArena Text: science14481459GPT-5.1
LMArena Text: medicine and healthcare14441456GPT-5.1
LMArena Text: legal and government14511459GPT-5.1
LMArena Text: business and finance14401431Claude Sonnet 4.5
FACTS Benchmark Suite40.6%45.0%GPT-5.1
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index53
Web design benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
Design Arena: websites11891187Claude Sonnet 4.5
Design Arena: UI components11701163Claude Sonnet 4.5
Design Arena: game dev11661178GPT-5.1
Design Arena: data viz11671204GPT-5.1
Design Arena: 3D11571060Claude Sonnet 4.5
Design Arena: all code categories11821170Claude Sonnet 4.5
Design Arena: SVG11151149GPT-5.1
Design Arena: ASCII art12051119Claude Sonnet 4.5
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index1111
General benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
SAGE (Vals AI)36.1%43.2%GPT-5.1
MedScribe (Vals AI)84.5%88.1%GPT-5.1
IFBenchNot measured72.9%Only GPT-5.1 measured
Long context reasoning (AA-LCR)Not measured80.0%Only GPT-5.1 measured
DTBench83.2%90.1%GPT-5.1
LMCA38.8%43.9%GPT-5.1
CL-benchNot measured23.7%Only GPT-5.1 measured
CL-bench LifeNot measured17.3%Only GPT-5.1 measured
LMArena Text14381443GPT-5.1
LMArena Text: instruction following14591443Claude Sonnet 4.5
LMArena Text: creative writing14421427Claude Sonnet 4.5
LMArena VisionNot measured1250Only GPT-5.1 measured
LMArena Text: English14501451GPT-5.1
LMArena Text: non-English14251431GPT-5.1
LMArena Text: Chinese14601495GPT-5.1
LMArena Text: German14271438GPT-5.1
LMArena Text: Japanese13901453GPT-5.1
LMArena Text: Korean14021401Claude Sonnet 4.5
LMArena Text: French14591450Claude Sonnet 4.5
LMArena Text: Spanish14581433Claude Sonnet 4.5
LMArena Text: Russian14371435Claude Sonnet 4.5
LMArena Text: Polish14231440GPT-5.1
LMArena Text: multi-turn14651450Claude Sonnet 4.5
LMArena Text: longer queries14751448Claude Sonnet 4.5
LMArena Text: writing and language14421428Claude Sonnet 4.5
LMArena Text: entertainment and media14281415Claude Sonnet 4.5
LMArena Vision: EnglishNot measured1252Only GPT-5.1 measured
LMArena Vision: ChineseNot measured1270Only GPT-5.1 measured
LMArena Vision: reading textNot measured1255Only GPT-5.1 measured
LMArena Vision: humorNot measured1263Only GPT-5.1 measured
LMArena Vision: captioningNot measured1252Only GPT-5.1 measured
LMArena Vision: recognizing thingsNot measured1232Only GPT-5.1 measured
LMArena Vision: creative writingNot measured1266Only GPT-5.1 measured
LMArena Document14501403Claude Sonnet 4.5
Neither model has a result on the other 12 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Sonnet 4.5 and GPT-5.1
BenchmarkClaude Sonnet 4.5GPT-5.1Leader
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 4.5$0.011Fits in one request
GPT-5.1$0.0063Fits in one request

GPT-5.1 costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request
GPT-5.1$0.092Fits in one request

GPT-5.1 costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request
GPT-5.1$0.350Fits in one request

GPT-5.1 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 4.5 and GPT-5.1
SpecificationAnthropic Claude Sonnet 4.5OpenAI GPT-5.1
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 29, 2025November 13, 2025
Context window1M400K
Input $/Mtok$3.00$1.25
Output $/Mtok$15.00$10.00
Coding index39.540.4
Independent measurements behind it33
Cost per solved task$1.16$1.02
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than GPT-5.1 for coding?

Claude Sonnet 4.5 and GPT-5.1 are level for coding, 39.5 against 40.4 on the Vibe Coding Index, so price and context decide. Pick Claude Sonnet 4.5 for a larger context window (1M against 400K tokens) and work measured by SWE-bench Verified or AA Coding Index, where it leads. Pick GPT-5.1 for output tokens 1.5x cheaper ($10.00 vs $15.00 per million) and a lower cost per solved task ($1.02 against $1.16).

Which is cheaper, Claude Sonnet 4.5 or GPT-5.1?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; GPT-5.1 costs $1.25 and $10.00. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and GPT-5.1 $1.02.

Which has the bigger context window, Claude Sonnet 4.5 or GPT-5.1?

Claude Sonnet 4.5, with 1M tokens against 400K.

How many benchmarks is the Claude Sonnet 4.5 vs GPT-5.1 comparison based on?

78 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 4.5's coding index rests on 3 independent benchmarks and GPT-5.1's on 3. Where only one model has a result, the page says so instead of naming a winner.

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