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Claude Sonnet 4.5 vs GPT-5.5

Updated October 21, 2026. 81 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Sonnet 4.5 Replace GPT-5.5
Claude Sonnet 4.5Anthropic
Coding
59.1
Overall
20.7
Output $/M
$15.00
0
GPT-5.5OpenAI
Coding
67.8
Overall
38.4
Output $/M
$30.00
81
vs boards won of 81 shared

Decision reading

Pick GPT-5.5 for coding: it scores 67.8 on the Vibe Coding Index against 59.1 for Claude Sonnet 4.5.

Pick Claude Sonnet 4.5 when output tokens cost 2.0x less, or when a solved task costs $1.16 against $1.65.

Model AClaude Sonnet 4.5Anthropic59.1/1002 independent benchmarks$1.16 per solved taskModel BGPT-5.5OpenAI67.8/1002 independent benchmarks$1.65 per solved task
Shared results
81
Claude Sonnet 4.5 only
11
GPT-5.5 only
51
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

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 59.1 from 2 benchmarks, GPT-5.5 67.8 from 2 benchmarks.
Widest category
Math, 30.2 points apart on average over 6 shared benchmarks.
Widest single gap
ARC-AGI-2: Claude Sonnet 4.5 13.6% against GPT-5.5 85.0%, 71.4 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 4.5 $15.00 against GPT-5.5 $30.00 per million output tokens, 2.0x apart.
Context window
Claude Sonnet 4.5 takes 1M tokens, GPT-5.5 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 4.5BarsGPT-5.5Ties
Coding012
Intelligence02
Agentic work07
Reasoning012
Math06
Knowledge012
Web design08
General022
All shared boards081
CodingLike-for-likeFour of these boards feed the Vibe Coding Index012
Coding benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
SWE-bench Verified74.8%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Multilingual67.0%Not measuredOnly Claude Sonnet 4.5 measured
LiveBench codingNot measured85.1%Only GPT-5.5 measured
LMArena WebDev13941513GPT-5.5
AA Coding Index52.174.9GPT-5.5
LiveCodeBench (Vals AI)73.0%85.3%GPT-5.5
SWE-bench Verified (Vals AI)70.0%82.6%GPT-5.5
Vibe Code Bench (Vals AI)22.6%69.8%GPT-5.5
Code migration (Vals AI)Not measured45.2%Only GPT-5.5 measured
ProgramBench (Vals AI)Not measured0.5%Only GPT-5.5 measured
Terminal-Bench 2.1 (Vals AI)Not measured76.4%Only GPT-5.5 measured
SkillsBench (Vals AI)Not measured62.5%Only GPT-5.5 measured
SciCodeNot measured56.1%Only GPT-5.5 measured
Terminal-Bench Hard (Artificial Analysis run)Not measured60.6%Only GPT-5.5 measured
Terminal-Bench46.5%84.7%GPT-5.5
FrontierCodeNot measured43.0%Only GPT-5.5 measured
GSO-Bench14.7%40.2%GPT-5.5
WeirdML47.7%84.9%GPT-5.5
MirrorCodeNot measured10.0%Only GPT-5.5 measured
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
ALE-BenchNot measured1943.0Only GPT-5.5 measured
LMArena Text: coding14881494GPT-5.5
LMArena Text: software and IT14731493GPT-5.5
LMArena WebDev: React13861506GPT-5.5
LMArena WebDev: HTML13991543GPT-5.5
LMArena WebDev: from an imageNot measured1532Only GPT-5.5 measured
Neither model has a result on the other 12 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
AA Intelligence Index20.738.4GPT-5.5
Epoch Capabilities Index146.7159.7GPT-5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index07
Agentic work benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
AA Agentic Index15.836.4GPT-5.5
Design Arena: agents building web apps10601117GPT-5.5
Design Arena: agents building full-stack apps10501089GPT-5.5
Design Arena: agents building mobile apps11371143GPT-5.5
Design Arena: agents building Android appsNot measured1169Only GPT-5.5 measured
Design Arena: agents building Godot gamesNot measured1173Only GPT-5.5 measured
Design Arena: agents building gamesNot measured1179Only GPT-5.5 measured
Design Arena: HTML slidesNot measured1067Only GPT-5.5 measured
Design Arena: PowerPoint slidesNot measured1108Only GPT-5.5 measured
LiveBench researchNot measured61.6%Only GPT-5.5 measured
LiveBench browserNot measured48.0%Only GPT-5.5 measured
LiveBench long agenticNot measured44.6%Only GPT-5.5 measured
SREBench (Vals AI)Not measured3.8%Only GPT-5.5 measured
Finance Agent (Vals AI)Not measured51.8%Only GPT-5.5 measured
Tax Agent Bench (Vals AI)Not measured21.8%Only GPT-5.5 measured
Legal Research Bench (Vals AI)Not measured40.4%Only GPT-5.5 measured
Excel Modeling Benchmark (Vals AI)Not measured64.5%Only GPT-5.5 measured
Time Horizon Index (Vals AI)Not measured8.3%Only GPT-5.5 measured
τ²-Bench TelecomNot measured93.9%Only GPT-5.5 measured
APEX-AgentsNot measured55.1%Only GPT-5.5 measured
METR time horizons67.4%Not measuredOnly Claude Sonnet 4.5 measured
Remote Labor Index2.1%6.3%GPT-5.5
GDPval42.5%Not measuredOnly Claude Sonnet 4.5 measured
OSWorld 2.0Not measured13.0%Only GPT-5.5 measured
DeepResearch Bench52.6%54.0%GPT-5.5
PostTrainBenchNot measured27.2%Only GPT-5.5 measured
OSWorld62.9%Not measuredOnly Claude Sonnet 4.5 measured
Vending-Bench 2$3,839$7,524GPT-5.5
Neither model has a result on the other 11 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index012
Reasoning benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
GPQA Diamond81.6%93.2%GPT-5.5
LiveBench reasoningNot measured89.7%Only GPT-5.5 measured
MMMU Pro (Vals AI)79.3%88.3%GPT-5.5
GPQA Diamond (Artificial Analysis run)Not measured93.5%Only GPT-5.5 measured
Humanity's Last Exam (Artificial Analysis run)Not measured45.8%Only GPT-5.5 measured
GPQA Diamond (Epoch AI run)82.3%90.7%GPT-5.5
ARC-AGI63.7%95.0%GPT-5.5
ARC-AGI-213.6%85.0%GPT-5.5
SimpleBench54.3%69.0%GPT-5.5
Chess puzzles10.0%63.0%GPT-5.5
Mystery game puzzles17.0%56.0%GPT-5.5
EBR-bench2.4%34.3%GPT-5.5
VPCT39.8%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts14621489GPT-5.5
LMArena Text: expert14831507GPT-5.5
LMArena Text: hard prompts in English14711483GPT-5.5
LMArena Vision: diagramsNot measured1325Only GPT-5.5 measured
LMArena Vision: homeworkNot measured1332Only GPT-5.5 measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index06
Math benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
AIME88.2%Not measuredOnly Claude Sonnet 4.5 measured
MGSM (Vals AI)94.3%Not measuredOnly Claude Sonnet 4.5 measured
OTIS Mock AIME77.8%84.4%GPT-5.5
FrontierMath, tiers 1 to 323.9%85.3%GPT-5.5
FrontierMath, tier 42.4%72.5%GPT-5.5
ProofBench19.0%50.0%GPT-5.5
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491487GPT-5.5
LMArena Text: mathematical work14621496GPT-5.5
Neither model has a result on the other 4 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index012
Knowledge benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
MMLU Pro87.4%88.1%GPT-5.5
LegalBench (Vals AI)84.1%86.5%GPT-5.5
CaseLaw (Vals AI)62.2%66.2%GPT-5.5
CorpFin (Vals AI)62.0%68.4%GPT-5.5
TaxEval (Vals AI)73.3%75.0%GPT-5.5
MortgageTax (Vals AI)64.0%68.8%GPT-5.5
MedQA (Vals AI)94.7%Not measuredOnly Claude Sonnet 4.5 measured
MedCode (Vals AI)44.1%49.1%GPT-5.5
SimpleQA Verified30.7%63.0%GPT-5.5
LMArena Text: science14481485GPT-5.5
LMArena Text: medicine and healthcare14441465GPT-5.5
LMArena Text: legal and government14511491GPT-5.5
LMArena Text: business and finance14401478GPT-5.5
Neither model has a result on the other 4 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index08
Web design benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
Design Arena: websites11901256GPT-5.5
Design Arena: UI components11731260GPT-5.5
Design Arena: game dev11661294GPT-5.5
Design Arena: data viz11671265GPT-5.5
Design Arena: 3D11581198GPT-5.5
Design Arena: all code categories11831260GPT-5.5
Design Arena: SVG11141234GPT-5.5
Design Arena: ASCII art12041254GPT-5.5
LiveBench designNot measured70.3%Only GPT-5.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index022
General benchmarks for Claude Sonnet 4.5 and GPT-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
LiveBench data analysisNot measured81.6%Only GPT-5.5 measured
Public Benefits Bench (Vals AI)Not measured60.9%Only GPT-5.5 measured
SAGE (Vals AI)36.1%51.5%GPT-5.5
MedScribe (Vals AI)84.5%86.9%GPT-5.5
Vals Multimodal IndexNot measured68.1%Only GPT-5.5 measured
IFBenchNot measured75.9%Only GPT-5.5 measured
Long context reasoning (AA-LCR)Not measured84.3%Only GPT-5.5 measured
DTBench83.2%96.0%GPT-5.5
LMCA38.8%54.3%GPT-5.5
Surface Evolver BenchNot measured88.1%Only GPT-5.5 measured
Furniture assemblyNot measured44.2%Only GPT-5.5 measured
ExploitBenchNot measured47.4%Only GPT-5.5 measured
CL-bench LifeNot measured22.2%Only GPT-5.5 measured
LMArena Text14381471GPT-5.5
LMArena Text: instruction following14591478GPT-5.5
LMArena Text: creative writing14421455GPT-5.5
LMArena VisionNot measured1297Only GPT-5.5 measured
LMArena Text: English14501470GPT-5.5
LMArena Text: non-English14251467GPT-5.5
LMArena Text: Chinese14601534GPT-5.5
LMArena Text: German14271480GPT-5.5
LMArena Text: Japanese13901499GPT-5.5
LMArena Text: Korean14021460GPT-5.5
LMArena Text: French14591485GPT-5.5
LMArena Text: Spanish14581468GPT-5.5
LMArena Text: Russian14371473GPT-5.5
LMArena Text: Polish14231465GPT-5.5
LMArena Text: multi-turn14651476GPT-5.5
LMArena Text: longer queries14751484GPT-5.5
LMArena Text: writing and language14421466GPT-5.5
LMArena Text: entertainment and media14281449GPT-5.5
LMArena Vision: EnglishNot measured1292Only GPT-5.5 measured
LMArena Vision: ChineseNot measured1360Only GPT-5.5 measured
LMArena Vision: reading textNot measured1306Only GPT-5.5 measured
LMArena Vision: humorNot measured1293Only GPT-5.5 measured
LMArena Vision: recognizing thingsNot measured1231Only GPT-5.5 measured
LMArena Vision: creative writingNot measured1301Only GPT-5.5 measured
LMArena Document14501486GPT-5.5
Neither model has a result on the other 8 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-5.5
BenchmarkClaude Sonnet 4.5GPT-5.5Leader
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-5.5$0.020Fits in one request

Claude Sonnet 4.5 costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request
GPT-5.5$0.340Fits in one request

Claude Sonnet 4.5 costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request
GPT-5.5$1.30Fits in one request

Claude Sonnet 4.5 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 4.5 and GPT-5.5
SpecificationAnthropic Claude Sonnet 4.5OpenAI GPT-5.5
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 29, 2025April 24, 2026
Context window1M1.05M
Input $/Mtok$3.00$5.00
Output $/Mtok$15.00$30.00
Coding index59.167.8
Independent measurements behind it22
Cost per solved task$1.16$1.65
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than GPT-5.5 for coding?

Pick GPT-5.5 for coding: it scores 67.8 on the Vibe Coding Index against 59.1 for Claude Sonnet 4.5. Pick Claude Sonnet 4.5 when output tokens cost 2.0x less, or when a solved task costs $1.16 against $1.65.

Which is cheaper, Claude Sonnet 4.5 or GPT-5.5?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; GPT-5.5 costs $5.00 and $30.00. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and GPT-5.5 $1.65.

Which has the bigger context window, Claude Sonnet 4.5 or GPT-5.5?

GPT-5.5, with 1.05M tokens against 1M.

How many benchmarks is the Claude Sonnet 4.5 vs GPT-5.5 comparison based on?

81 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 4.5's coding index rests on 2 independent benchmarks and GPT-5.5's on 2. Where only one model has a result, the page says so instead of naming a winner.

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