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Claude Sonnet 4.5 vs Gemini 3.5 Flash

Gemini 3.5 Flash leads Claude Sonnet 4.5 on coding, 39.8 to 39.5 on the Vibe Coding Index, and Gemini 3.5 Flash costs 1.7x less per output token ($9.00 vs $15.00 per million). Updated October 21, 2026; 75 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace Gemini 3.5 Flash
Claude Sonnet 4.5Anthropic
Coding
39.5
Overall
49.5
Output $/M
$15.00
2
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
73
vs boards won of 75 shared

Claude Sonnet 4.5 or Gemini 3.5 Flash: which to pick

Claude Sonnet 4.5 and Gemini 3.5 Flash are level for coding, 39.5 against 39.8 on the Vibe Coding Index, so price and context decide.

Pick Claude Sonnet 4.5 for a lower cost per solved task ($1.16 against $1.21) and work measured by LegalBench (Vals AI) or MedScribe (Vals AI), where it leads. Pick Gemini 3.5 Flash for output tokens 1.7x cheaper ($9.00 vs $15.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved taskModel BGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved task
Shared results
75
Claude Sonnet 4.5 only
20
Gemini 3.5 Flash only
37
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, Gemini 3.5 Flash 39.8 from 4 benchmarks.
Widest category
Math, 18.0 points apart on average over 6 shared benchmarks.
Widest single gap
ARC-AGI-2: Claude Sonnet 4.5 13.6% against Gemini 3.5 Flash 72.1%, 58.5 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 4.5 $15.00 against Gemini 3.5 Flash $9.00 per million output tokens, 1.7x apart.
Context window
Claude Sonnet 4.5 takes 1M tokens, Gemini 3.5 Flash 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 4.5BarsGemini 3.5 FlashTies
Coding09
Intelligence02
Agentic work04
Reasoning012
Math06
Knowledge111
Web design08
General121
All shared boards273
CodingLike-for-likeSix of these boards feed the Vibe Coding Index09
Coding benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
SWE-bench Verified74.8%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Multilingual67.0%Not measuredOnly Claude Sonnet 4.5 measured
LMArena WebDev13941499Gemini 3.5 Flash
AA Coding Index52.1Not measuredOnly Claude Sonnet 4.5 measured
LiveCodeBench (Vals AI)73.0%87.6%Gemini 3.5 Flash
SWE-bench Verified (Vals AI)70.0%78.8%Gemini 3.5 Flash
Terminal-Bench 4 (Vals AI)Not measured6.1%Only Gemini 3.5 Flash measured
Vibe Code Bench (Vals AI)22.6%48.7%Gemini 3.5 Flash
Code migration (Vals AI)Not measured26.8%Only Gemini 3.5 Flash measured
ProgramBench (Vals AI)Not measured0.0%Only Gemini 3.5 Flash measured
Terminal-Bench 2.1 (Vals AI)Not measured74.2%Only Gemini 3.5 Flash measured
SkillsBench (Vals AI)Not measured52.7%Only Gemini 3.5 Flash measured
SciCodeNot measured53.9%Only Gemini 3.5 Flash measured
Terminal-Bench Hard (Artificial Analysis run)Not measured46.2%Only Gemini 3.5 Flash measured
Terminal-Bench46.5%Not measuredOnly Claude Sonnet 4.5 measured
GSO-Bench14.7%Not measuredOnly Claude Sonnet 4.5 measured
WeirdML47.7%62.6%Gemini 3.5 Flash
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
ALE-BenchNot measured911.0Only Gemini 3.5 Flash measured
LMArena Text: coding14881493Gemini 3.5 Flash
LMArena Text: software and IT14731494Gemini 3.5 Flash
LMArena WebDev: React13861495Gemini 3.5 Flash
LMArena WebDev: HTML13991522Gemini 3.5 Flash
LMArena WebDev: from an imageNot measured1504Only Gemini 3.5 Flash measured
SciCodeNot measured12.3%Only Gemini 3.5 Flash measured
Neither model has a result on the other 14 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
AA Intelligence Index20.733.6Gemini 3.5 Flash
Epoch Capabilities Index146.7154.9Gemini 3.5 Flash
Agentic workLike-for-likePublic boards, shown as published, kept out of the index04
Agentic work benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
AA Agentic Index15.8Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building web apps10591202Gemini 3.5 Flash
Design Arena: agents building full-stack apps10501197Gemini 3.5 Flash
Design Arena: agents building mobile apps11371174Gemini 3.5 Flash
Design Arena: agents building Android appsNot measured1184Only Gemini 3.5 Flash measured
Design Arena: agents building Godot gamesNot measured1098Only Gemini 3.5 Flash measured
Design Arena: agents building gamesNot measured1180Only Gemini 3.5 Flash measured
Design Arena: HTML slidesNot measured1142Only Gemini 3.5 Flash measured
Design Arena: PowerPoint slidesNot measured1179Only Gemini 3.5 Flash measured
Finance Agent (Vals AI)Not measured57.9%Only Gemini 3.5 Flash measured
Tax Agent Bench (Vals AI)Not measured21.6%Only Gemini 3.5 Flash measured
Legal Research Bench (Vals AI)Not measured30.8%Only Gemini 3.5 Flash measured
Excel Modeling Benchmark (Vals AI)Not measured63.5%Only Gemini 3.5 Flash measured
Terminal-Bench-Science (Vals AI)Not measured5.7%Only Gemini 3.5 Flash measured
τ²-Bench TelecomNot measured95.6%Only Gemini 3.5 Flash measured
APEX-AgentsNot measured27.5%Only Gemini 3.5 Flash 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%Not measuredOnly Claude Sonnet 4.5 measured
OSWorld62.9%Not measuredOnly Claude Sonnet 4.5 measured
Vending-Bench 2$3,839$5,396Gemini 3.5 Flash
Berkeley Function Calling Leaderboard (BFCL)73.2%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 18 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index012
Reasoning benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
GPQA Diamond81.6%92.7%Gemini 3.5 Flash
MMMU Pro (Vals AI)79.3%88.3%Gemini 3.5 Flash
GPQA Diamond (Artificial Analysis run)Not measured92.2%Only Gemini 3.5 Flash measured
Humanity's Last Exam (Artificial Analysis run)Not measured42.7%Only Gemini 3.5 Flash measured
GPQA Diamond (Epoch AI run)82.3%92.8%Gemini 3.5 Flash
ARC-AGI63.7%92.5%Gemini 3.5 Flash
ARC-AGI-213.6%72.1%Gemini 3.5 Flash
SimpleBench54.3%76.7%Gemini 3.5 Flash
Chess puzzles10.0%45.0%Gemini 3.5 Flash
Mystery game puzzles17.0%32.0%Gemini 3.5 Flash
EBR-bench2.4%4.8%Gemini 3.5 Flash
VPCT39.8%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts14621488Gemini 3.5 Flash
LMArena Text: expert14831495Gemini 3.5 Flash
LMArena Text: hard prompts in English14711483Gemini 3.5 Flash
LMArena Vision: diagramsNot measured1323Only Gemini 3.5 Flash measured
LMArena Vision: homeworkNot measured1330Only Gemini 3.5 Flash 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 index06
Math benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
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%95.6%Gemini 3.5 Flash
FrontierMath, tiers 1 to 323.9%62.8%Gemini 3.5 Flash
FrontierMath, tier 42.4%26.8%Gemini 3.5 Flash
ProofBench19.0%31.0%Gemini 3.5 Flash
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491504Gemini 3.5 Flash
LMArena Text: mathematical work14621495Gemini 3.5 Flash
Neither model has a result on the other 4 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index111
Knowledge benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
MMLU Pro87.4%89.5%Gemini 3.5 Flash
LegalBench (Vals AI)84.1%83.6%Claude Sonnet 4.5
CaseLaw (Vals AI)62.2%Not measuredOnly Claude Sonnet 4.5 measured
CorpFin (Vals AI)62.0%64.7%Gemini 3.5 Flash
TaxEval (Vals AI)73.3%74.4%Gemini 3.5 Flash
MortgageTax (Vals AI)64.0%68.1%Gemini 3.5 Flash
MedQA (Vals AI)94.7%Not measuredOnly Claude Sonnet 4.5 measured
MedCode (Vals AI)44.1%55.8%Gemini 3.5 Flash
SimpleQA Verified30.7%66.2%Gemini 3.5 Flash
LMArena Text: science14481495Gemini 3.5 Flash
LMArena Text: medicine and healthcare14441483Gemini 3.5 Flash
LMArena Text: legal and government14511488Gemini 3.5 Flash
LMArena Text: business and finance14401467Gemini 3.5 Flash
FACTS Benchmark Suite40.6%63.1%Gemini 3.5 Flash
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 Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
Design Arena: websites11901268Gemini 3.5 Flash
Design Arena: UI components11731273Gemini 3.5 Flash
Design Arena: game dev11661263Gemini 3.5 Flash
Design Arena: data viz11671236Gemini 3.5 Flash
Design Arena: 3D11581244Gemini 3.5 Flash
Design Arena: all code categories11831266Gemini 3.5 Flash
Design Arena: SVG11151254Gemini 3.5 Flash
Design Arena: ASCII art12051254Gemini 3.5 Flash
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index121
General benchmarks for Claude Sonnet 4.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
Public Benefits Bench (Vals AI)Not measured59.5%Only Gemini 3.5 Flash measured
SAGE (Vals AI)36.1%49.9%Gemini 3.5 Flash
MedScribe (Vals AI)84.5%76.6%Claude Sonnet 4.5
Vals Multimodal IndexNot measured62.9%Only Gemini 3.5 Flash measured
IFBenchNot measured76.3%Only Gemini 3.5 Flash measured
Long context reasoning (AA-LCR)Not measured74.3%Only Gemini 3.5 Flash measured
DTBench83.2%94.7%Gemini 3.5 Flash
LMCA38.8%47.1%Gemini 3.5 Flash
Surface Evolver BenchNot measured58.1%Only Gemini 3.5 Flash measured
LMArena Text14381482Gemini 3.5 Flash
LMArena Text: instruction following14591467Gemini 3.5 Flash
LMArena Text: creative writing14421470Gemini 3.5 Flash
LMArena VisionNot measured1308Only Gemini 3.5 Flash measured
LMArena Text: English14501481Gemini 3.5 Flash
LMArena Text: non-English14251475Gemini 3.5 Flash
LMArena Text: Chinese14601527Gemini 3.5 Flash
LMArena Text: German14271494Gemini 3.5 Flash
LMArena Text: Japanese13901486Gemini 3.5 Flash
LMArena Text: Korean14021448Gemini 3.5 Flash
LMArena Text: French14591490Gemini 3.5 Flash
LMArena Text: Spanish14581480Gemini 3.5 Flash
LMArena Text: Russian14371493Gemini 3.5 Flash
LMArena Text: Polish14231516Gemini 3.5 Flash
LMArena Text: multi-turn14651481Gemini 3.5 Flash
LMArena Text: longer queries14751483Gemini 3.5 Flash
LMArena Text: writing and language14421478Gemini 3.5 Flash
LMArena Text: entertainment and media14281459Gemini 3.5 Flash
LMArena Vision: EnglishNot measured1305Only Gemini 3.5 Flash measured
LMArena Vision: ChineseNot measured1377Only Gemini 3.5 Flash measured
LMArena Vision: reading textNot measured1317Only Gemini 3.5 Flash measured
LMArena Vision: humorNot measured1321Only Gemini 3.5 Flash measured
LMArena Vision: creative writingNot measured1301Only Gemini 3.5 Flash measured
LMArena Document14501463Gemini 3.5 Flash
Neither model has a result on the other 13 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 Gemini 3.5 Flash
BenchmarkClaude Sonnet 4.5Gemini 3.5 FlashLeader
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
Gemini 3.5 Flash$0.0060Fits in one request

Gemini 3.5 Flash costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request
Gemini 3.5 Flash$0.102Fits in one request

Gemini 3.5 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request
Gemini 3.5 Flash$0.390Fits in one request

Gemini 3.5 Flash 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 Gemini 3.5 Flash
SpecificationAnthropic Claude Sonnet 4.5Google Gemini 3.5 Flash
MakerAnthropicGoogle
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 29, 2025May 19, 2026
Context window1M1.05M
Input $/Mtok$3.00$1.50
Output $/Mtok$15.00$9.00
Coding index39.539.8
Independent measurements behind it34
Cost per solved task$1.16$1.21
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than Gemini 3.5 Flash for coding?

Claude Sonnet 4.5 and Gemini 3.5 Flash are level for coding, 39.5 against 39.8 on the Vibe Coding Index, so price and context decide. Pick Claude Sonnet 4.5 for a lower cost per solved task ($1.16 against $1.21) and work measured by LegalBench (Vals AI) or MedScribe (Vals AI), where it leads. Pick Gemini 3.5 Flash for output tokens 1.7x cheaper ($9.00 vs $15.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Sonnet 4.5 or Gemini 3.5 Flash?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; Gemini 3.5 Flash costs $1.50 and $9.00. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and Gemini 3.5 Flash $1.21.

Which has the bigger context window, Claude Sonnet 4.5 or Gemini 3.5 Flash?

Gemini 3.5 Flash, with 1.05M tokens against 1M.

How many benchmarks is the Claude Sonnet 4.5 vs Gemini 3.5 Flash comparison based on?

75 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 4.5's coding index rests on 3 independent benchmarks and Gemini 3.5 Flash's on 4. Where only one model has a result, the page says so instead of naming a winner.

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