Enter opens the highlighted result. Esc closes.

Claude Sonnet 5.5 vs Gemini 3.5 Flash

Claude Sonnet 5.5 leads Gemini 3.5 Flash on coding, 87.3 to 39.8 on the Vibe Coding Index, at about the same output price ($10.00 vs $9.00 per million). Updated October 22, 2026; 75 benchmarks have a result for both.

Replace Claude Sonnet 5.5 Replace Gemini 3.5 Flash
Claude Sonnet 5.5Anthropic
Coding
87.3
Overall
82.8
Output $/M
$10.00
58
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
17
vs boards won of 75 shared

Claude Sonnet 5.5 or Gemini 3.5 Flash: which to pick

Pick Claude Sonnet 5.5 for coding: it scores 87.3 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash.

Pick Gemini 3.5 Flash for output tokens 1.1x cheaper ($9.00 vs $10.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Sonnet 5.5Anthropic87.3/1005 independent benchmarksNo cost per solved taskModel BGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved task
Shared results
75
Claude Sonnet 5.5 only
21
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 5.5 87.3 from 5 benchmarks, Gemini 3.5 Flash 39.8 from 4 benchmarks.
Widest category
Math, 26.2 points apart on average over 6 shared benchmarks.
Widest single gap
Terminal-Bench 4 (Vals AI): Claude Sonnet 5.5 64.1% against Gemini 3.5 Flash 6.1%, 77.4 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 5.5 $10.00 against Gemini 3.5 Flash $9.00 per million output tokens, 1.1x apart.
Context window
Claude Sonnet 5.5 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 5.5BarsGemini 3.5 FlashTies
Coding140
Intelligence20
Agentic work90
Reasoning90
Math51
Knowledge15
Web design60
General1211
All shared boards5817
CodingLike-for-likeSix of these boards feed the Vibe Coding Index140
Coding benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
LiveBench coding94.7%Not measuredOnly Claude Sonnet 5.5 measured
LMArena WebDev17681499Claude Sonnet 5.5
LiveCodeBench (Vals AI)Not measured87.6%Only Gemini 3.5 Flash measured
SWE-bench Verified (Vals AI)Not measured78.8%Only Gemini 3.5 Flash measured
Terminal-Bench 4 (Vals AI)64.1%6.1%Claude Sonnet 5.5
Vibe Code Bench (Vals AI)92.4%48.7%Claude Sonnet 5.5
Code migration (Vals AI)69.8%26.8%Claude Sonnet 5.5
ProgramBench (Vals AI)6.5%0.0%Claude Sonnet 5.5
IOI (Vals AI)83.1%Not measuredOnly Claude Sonnet 5.5 measured
Terminal-Bench 2.1 (Vals AI)83.2%74.2%Claude Sonnet 5.5
SWE-bench Multimodal (Vals AI)58.3%Not measuredOnly Claude Sonnet 5.5 measured
SkillsBench (Vals AI)Not measured52.7%Only Gemini 3.5 Flash measured
CyberBench (Vals AI)59.6%Not measuredOnly Claude Sonnet 5.5 measured
SciCode61.0%53.9%Claude Sonnet 5.5
Terminal-Bench Hard (Artificial Analysis run)Not measured46.2%Only Gemini 3.5 Flash measured
FrontierCode52.1%Not measuredOnly Claude Sonnet 5.5 measured
FrontierSWE61.9%Not measuredOnly Claude Sonnet 5.5 measured
WeirdMLNot measured62.6%Only Gemini 3.5 Flash measured
ALE-Bench1819.1911.0Claude Sonnet 5.5
LMArena Text: coding15131493Claude Sonnet 5.5
LMArena Text: software and IT15041494Claude Sonnet 5.5
LMArena WebDev: React18171495Claude Sonnet 5.5
LMArena WebDev: HTML17411522Claude Sonnet 5.5
LMArena WebDev: from an image17371504Claude Sonnet 5.5
SciCode13.8%12.3%Claude Sonnet 5.5
Neither model has a result on the other 14 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
AA Intelligence Index56.033.6Claude Sonnet 5.5
Epoch Capabilities Index166.2154.9Claude Sonnet 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index90
Agentic work benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
Design Arena: agents building web apps13051202Claude Sonnet 5.5
Design Arena: agents building full-stack appsNot measured1197Only Gemini 3.5 Flash measured
Design Arena: agents building mobile apps12601174Claude Sonnet 5.5
Design Arena: agents building Android appsNot measured1185Only 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 measured1093Only Gemini 3.5 Flash measured
Design Arena: PowerPoint slidesNot measured1154Only Gemini 3.5 Flash measured
Design Arena: spreadsheets1260Not measuredOnly Claude Sonnet 5.5 measured
LiveBench research83.6%Not measuredOnly Claude Sonnet 5.5 measured
LiveBench browser84.0%Not measuredOnly Claude Sonnet 5.5 measured
LiveBench long agentic78.8%Not measuredOnly Claude Sonnet 5.5 measured
SREBench (Vals AI)30.1%Not measuredOnly Claude Sonnet 5.5 measured
Finance Agent (Vals AI)58.1%57.9%Claude Sonnet 5.5
Tax Agent Bench (Vals AI)42.0%21.6%Claude Sonnet 5.5
Legal Research Bench (Vals AI)48.1%30.8%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%63.5%Claude Sonnet 5.5
BioMysteryBench (Vals AI)81.1%Not measuredOnly Claude Sonnet 5.5 measured
Terminal-Bench-Science (Vals AI)47.1%5.7%Claude Sonnet 5.5
Vals Science Index59.1%Not measuredOnly Claude Sonnet 5.5 measured
τ²-Bench TelecomNot measured95.6%Only Gemini 3.5 Flash measured
APEX-Agents75.5%27.5%Claude Sonnet 5.5
SpireClimb1.3%Not measuredOnly Claude Sonnet 5.5 measured
Vending-Bench 2$11,165$5,396Claude Sonnet 5.5
Neither model has a result on the other 16 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index90
Reasoning benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
GPQA DiamondNot measured92.7%Only Gemini 3.5 Flash measured
LiveBench reasoning91.6%Not measuredOnly Claude Sonnet 5.5 measured
MysteryMechanism (Vals AI)49.1%Not measuredOnly Claude Sonnet 5.5 measured
MMMU Pro (Vals AI)Not measured88.3%Only Gemini 3.5 Flash measured
GPQA Diamond (Artificial Analysis run)Not measured92.2%Only Gemini 3.5 Flash measured
Humanity's Last Exam (Artificial Analysis run)55.0%42.7%Claude Sonnet 5.5
GPQA Diamond (Epoch AI run)95.6%92.8%Claude Sonnet 5.5
ARC-AGINot measured92.5%Only Gemini 3.5 Flash measured
ARC-AGI-2Not measured72.1%Only Gemini 3.5 Flash measured
SimpleBenchNot measured76.7%Only Gemini 3.5 Flash measured
Chess puzzles59.0%45.0%Claude Sonnet 5.5
Mystery game puzzles65.0%32.0%Claude Sonnet 5.5
EBR-benchNot measured4.8%Only Gemini 3.5 Flash measured
LMArena Text: hard prompts14941488Claude Sonnet 5.5
LMArena Text: expert15311495Claude Sonnet 5.5
LMArena Text: hard prompts in English15021483Claude Sonnet 5.5
LMArena Vision: diagrams13291323Claude Sonnet 5.5
LMArena Vision: homework13311330Claude Sonnet 5.5
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index51
Math benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
OTIS Mock AIME100.0%95.6%Claude Sonnet 5.5
FrontierMath, tiers 1 to 388.8%62.8%Claude Sonnet 5.5
FrontierMath, tier 480.5%26.8%Claude Sonnet 5.5
ProofBench100.0%31.0%Claude Sonnet 5.5
LMArena Text: math14971504Gemini 3.5 Flash
LMArena Text: mathematical work15101495Claude 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 index15
Knowledge benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
MMLU ProNot measured89.5%Only Gemini 3.5 Flash measured
LegalBench (Vals AI)Not measured83.6%Only Gemini 3.5 Flash measured
CorpFin (Vals AI)Not measured64.7%Only Gemini 3.5 Flash measured
TaxEval (Vals AI)Not measured74.4%Only Gemini 3.5 Flash measured
MortgageTax (Vals AI)Not measured68.1%Only Gemini 3.5 Flash measured
MedCode (Vals AI)52.9%55.8%Gemini 3.5 Flash
SimpleQA Verified46.5%66.2%Gemini 3.5 Flash
LMArena Text: science14831495Gemini 3.5 Flash
LMArena Text: medicine and healthcare14641483Gemini 3.5 Flash
LMArena Text: legal and government14831488Gemini 3.5 Flash
LMArena Text: business and finance14681467Claude Sonnet 5.5
FACTS Benchmark SuiteNot measured63.1%Only Gemini 3.5 Flash measured
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index60
Web design benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
Design Arena: websites13261267Claude Sonnet 5.5
Design Arena: UI components13681269Claude Sonnet 5.5
Design Arena: game dev14711263Claude Sonnet 5.5
Design Arena: data viz13921236Claude Sonnet 5.5
Design Arena: 3D14451243Claude Sonnet 5.5
Design Arena: all code categories13641266Claude Sonnet 5.5
Design Arena: SVGNot measured1253Only Gemini 3.5 Flash measured
Design Arena: ASCII artNot measured1254Only Gemini 3.5 Flash measured
LiveBench design85.0%Not measuredOnly Claude Sonnet 5.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index1211
General benchmarks for Claude Sonnet 5.5 and Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 3.5 FlashLeader
Vals Index70.8%Not measuredOnly Claude Sonnet 5.5 measured
LiveBench data analysis59.5%Not measuredOnly Claude Sonnet 5.5 measured
Public Benefits Bench (Vals AI)67.2%59.5%Claude Sonnet 5.5
SAGE (Vals AI)51.8%49.9%Claude Sonnet 5.5
MedScribe (Vals AI)91.1%76.6%Claude Sonnet 5.5
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)82.7%74.3%Claude Sonnet 5.5
DTBench97.3%94.7%Claude Sonnet 5.5
LMCA68.3%47.1%Claude Sonnet 5.5
Surface Evolver BenchNot measured58.1%Only Gemini 3.5 Flash measured
Furniture assembly75.0%Not measuredOnly Claude Sonnet 5.5 measured
LMArena Text14731482Gemini 3.5 Flash
LMArena Text: instruction following14921467Claude Sonnet 5.5
LMArena Text: creative writing14671470Gemini 3.5 Flash
LMArena Vision12871308Gemini 3.5 Flash
LMArena Text: English14841481Claude Sonnet 5.5
LMArena Text: non-English14561475Gemini 3.5 Flash
LMArena Text: Chinese15351527Claude Sonnet 5.5
LMArena Text: GermanNot measured1494Only Gemini 3.5 Flash measured
LMArena Text: JapaneseNot measured1486Only Gemini 3.5 Flash measured
LMArena Text: KoreanNot measured1448Only Gemini 3.5 Flash measured
LMArena Text: French14991490Claude Sonnet 5.5
LMArena Text: Spanish14511480Gemini 3.5 Flash
LMArena Text: Russian14541493Gemini 3.5 Flash
LMArena Text: PolishNot measured1516Only Gemini 3.5 Flash measured
LMArena Text: multi-turn14651481Gemini 3.5 Flash
LMArena Text: longer queries14951483Claude Sonnet 5.5
LMArena Text: writing and language14741478Gemini 3.5 Flash
LMArena Text: entertainment and media14611459Claude Sonnet 5.5
LMArena Vision: English12891305Gemini 3.5 Flash
LMArena Vision: ChineseNot measured1377Only Gemini 3.5 Flash measured
LMArena Vision: reading text12971317Gemini 3.5 Flash
LMArena Vision: humorNot measured1321Only Gemini 3.5 Flash measured
LMArena Vision: creative writing12421301Gemini 3.5 Flash
LMArena DocumentNot measured1463Only Gemini 3.5 Flash 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 Gemini 3.5 Flash
BenchmarkClaude Sonnet 5.5Gemini 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 5.5$0.0070Fits 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 5.5$0.130Fits 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 5.5$0.500Fits 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 5.5 and Gemini 3.5 Flash
SpecificationAnthropic Claude Sonnet 5.5Google Gemini 3.5 Flash
MakerAnthropicGoogle
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 28, 2026May 19, 2026
Context window1M1.05M
Input $/Mtok$2.00$1.50
Output $/Mtok$10.00$9.00
Coding index87.339.8
Independent measurements behind it54
Cost per solved taskNot computable$1.21
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 5.5 better than Gemini 3.5 Flash for coding?

Pick Claude Sonnet 5.5 for coding: it scores 87.3 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash. Pick Gemini 3.5 Flash for output tokens 1.1x cheaper ($9.00 vs $10.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Sonnet 5.5 or Gemini 3.5 Flash?

Claude Sonnet 5.5 costs $2.00 per million input tokens and $10.00 per million output tokens; Gemini 3.5 Flash costs $1.50 and $9.00. Cost per solved task is known for Gemini 3.5 Flash only.

Which has the bigger context window, Claude Sonnet 5.5 or Gemini 3.5 Flash?

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

How many benchmarks is the Claude Sonnet 5.5 vs Gemini 3.5 Flash comparison based on?

75 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 Gemini 3.5 Flash's on 4. Where only one model has a result, the page says so instead of naming a winner.

Compare next

Embed this comparison on your site

Free under CC BY 4.0, while the source link stays visible. Preview the frame · Terms and other embeds

<iframe src="https://llmbenchmark.ai/embed/compare/claude-sonnet-5-5-vs-gemini-3-5-flash" title="Claude Sonnet 5.5 vs Gemini 3.5 Flash, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/claude-sonnet-5-5-vs-gemini-3-5-flash">LLMBenchmark.ai, Claude Sonnet 5.5 vs Gemini 3.5 Flash</a></p>