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Gemini 3.5 Flash vs GPT-5.1

GPT-5.1 leads Gemini 3.5 Flash on coding, 40.4 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; 83 benchmarks have a result for both.

Replace Gemini 3.5 Flash Replace GPT-5.1
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
79
GPT-5.1OpenAI
Coding
40.4
Overall
55.0
Output $/M
$10.00
4
vs boards won of 83 shared

Gemini 3.5 Flash or GPT-5.1: which to pick

Gemini 3.5 Flash and GPT-5.1 are level for coding, 39.8 against 40.4 on the Vibe Coding Index, so price and context decide.

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 400K tokens). Pick GPT-5.1 for a lower cost per solved task ($1.02 against $1.21) and work measured by LegalBench (Vals AI) or TaxEval (Vals AI), where it leads.

Model AGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved taskModel BGPT-5.1OpenAI40.4/1003 independent benchmarks$1.02 per solved task
Shared results
83
Gemini 3.5 Flash only
29
GPT-5.1 only
18
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
Gemini 3.5 Flash 39.8 from 4 benchmarks, GPT-5.1 40.4 from 3 benchmarks.
Widest category
Agentic work, 19.1 points apart on average over 2 shared benchmarks.
Widest single gap
ARC-AGI-2: Gemini 3.5 Flash 72.1% against GPT-5.1 17.6%, 54.4 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash $9.00 against GPT-5.1 $10.00 per million output tokens, 1.1x apart.
Context window
Gemini 3.5 Flash takes 1.05M 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
CategoryGemini 3.5 FlashBarsGPT-5.1Ties
Coding110
Intelligence20
Agentic work20
Reasoning150
Math30
Knowledge102
Web design80
General282
All shared boards794
CodingLike-for-likeSix of these boards feed the Vibe Coding Index110
Coding benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
SWE-bench VerifiedNot measured66.0%Only GPT-5.1 measured
LMArena WebDev14991396Gemini 3.5 Flash
AA Coding IndexNot measured49.4Only GPT-5.1 measured
LiveCodeBench (Vals AI)87.6%86.5%Gemini 3.5 Flash
SWE-bench Verified (Vals AI)78.8%69.8%Gemini 3.5 Flash
Terminal-Bench 4 (Vals AI)6.1%Not measuredOnly Gemini 3.5 Flash measured
Vibe Code Bench (Vals AI)48.7%24.6%Gemini 3.5 Flash
Code migration (Vals AI)26.8%Not measuredOnly Gemini 3.5 Flash measured
ProgramBench (Vals AI)0.0%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench 2.1 (Vals AI)74.2%Not measuredOnly Gemini 3.5 Flash measured
SkillsBench (Vals AI)52.7%Not measuredOnly Gemini 3.5 Flash measured
LiveCodeBench (Artificial Analysis run)Not measured86.8%Only GPT-5.1 measured
SciCode53.9%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench Hard (Artificial Analysis run)46.2%45.5%Gemini 3.5 Flash
Terminal-BenchNot measured47.6%Only GPT-5.1 measured
GSO-BenchNot measured13.7%Only GPT-5.1 measured
WeirdML62.6%60.8%Gemini 3.5 Flash
ALE-Bench911.0Not measuredOnly Gemini 3.5 Flash measured
LMArena Text: coding14931453Gemini 3.5 Flash
LMArena Text: software and IT14941454Gemini 3.5 Flash
LMArena WebDev: React14951307Gemini 3.5 Flash
LMArena WebDev: HTML15221405Gemini 3.5 Flash
LMArena WebDev: from an image15041421Gemini 3.5 Flash
SciCode12.3%Not measuredOnly Gemini 3.5 Flash measured
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
AA Intelligence Index33.624.7Gemini 3.5 Flash
Epoch Capabilities Index154.9149.8Gemini 3.5 Flash
Agentic workLike-for-likePublic boards, shown as published, kept out of the index20
Agentic work benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
Design Arena: agents building web apps1202Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building full-stack apps1197Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building mobile apps1174Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building Android apps1185Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building Godot games1098Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building games1180Not measuredOnly Gemini 3.5 Flash measured
Design Arena: HTML slides1093Not measuredOnly Gemini 3.5 Flash measured
Design Arena: PowerPoint slides1154Not measuredOnly Gemini 3.5 Flash measured
Finance Agent (Vals AI)57.9%Not measuredOnly Gemini 3.5 Flash measured
Tax Agent Bench (Vals AI)21.6%Not measuredOnly Gemini 3.5 Flash measured
Legal Research Bench (Vals AI)30.8%Not measuredOnly Gemini 3.5 Flash measured
Excel Modeling Benchmark (Vals AI)63.5%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench-Science (Vals AI)5.7%Not measuredOnly Gemini 3.5 Flash measured
τ²-Bench Telecom95.6%81.9%Gemini 3.5 Flash
APEX-Agents27.5%Not measuredOnly Gemini 3.5 Flash measured
DeepResearch BenchNot measured42.8%Only GPT-5.1 measured
Vending-Bench 2$5,396$1,473Gemini 3.5 Flash
Neither model has a result on the other 24 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index150
Reasoning benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
GPQA Diamond92.7%86.6%Gemini 3.5 Flash
MMMU Pro (Vals AI)88.3%83.2%Gemini 3.5 Flash
GPQA Diamond (Artificial Analysis run)92.2%87.3%Gemini 3.5 Flash
Humanity's Last Exam (Artificial Analysis run)42.7%28.5%Gemini 3.5 Flash
GPQA Diamond (Epoch AI run)92.8%87.6%Gemini 3.5 Flash
ARC-AGI92.5%72.8%Gemini 3.5 Flash
ARC-AGI-272.1%17.6%Gemini 3.5 Flash
SimpleBench76.7%53.2%Gemini 3.5 Flash
Chess puzzles45.0%42.0%Gemini 3.5 Flash
Mystery game puzzles32.0%19.0%Gemini 3.5 Flash
EBR-bench4.8%Not measuredOnly Gemini 3.5 Flash measured
VPCTNot measured58.7%Only GPT-5.1 measured
LMArena Text: hard prompts14881457Gemini 3.5 Flash
LMArena Text: expert14951470Gemini 3.5 Flash
LMArena Text: hard prompts in English14831462Gemini 3.5 Flash
LMArena Vision: diagrams13231264Gemini 3.5 Flash
LMArena Vision: homework13301272Gemini 3.5 Flash
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index30
Math benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
AIMENot measured93.3%Only GPT-5.1 measured
MGSM (Vals AI)Not measured93.0%Only GPT-5.1 measured
AA Math IndexNot measured94.0Only GPT-5.1 measured
AIME 2025 (Artificial Analysis run)Not measured94.0%Only GPT-5.1 measured
OTIS Mock AIME95.6%88.6%Gemini 3.5 Flash
FrontierMath, tiers 1 to 362.8%Not measuredOnly Gemini 3.5 Flash measured
FrontierMath, tier 426.8%Not measuredOnly Gemini 3.5 Flash measured
ProofBench31.0%Not measuredOnly Gemini 3.5 Flash measured
LMArena Text: math15041446Gemini 3.5 Flash
LMArena Text: mathematical work14951449Gemini 3.5 Flash
Neither model has a result on the other 3 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index102
Knowledge benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
MMLU Pro89.5%86.4%Gemini 3.5 Flash
LegalBench (Vals AI)83.6%85.7%GPT-5.1
CaseLaw (Vals AI)Not measured73.4%Only GPT-5.1 measured
CorpFin (Vals AI)64.7%63.8%Gemini 3.5 Flash
TaxEval (Vals AI)74.4%74.9%GPT-5.1
MortgageTax (Vals AI)68.1%61.4%Gemini 3.5 Flash
MedQA (Vals AI)Not measured96.4%Only GPT-5.1 measured
MedCode (Vals AI)55.8%52.7%Gemini 3.5 Flash
MMLU Pro (Artificial Analysis run)Not measured87.0%Only GPT-5.1 measured
SimpleQA Verified66.2%48.0%Gemini 3.5 Flash
LMArena Text: science14951459Gemini 3.5 Flash
LMArena Text: medicine and healthcare14831456Gemini 3.5 Flash
LMArena Text: legal and government14881459Gemini 3.5 Flash
LMArena Text: business and finance14671431Gemini 3.5 Flash
FACTS Benchmark Suite63.1%45.0%Gemini 3.5 Flash
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
Design Arena: websites12671187Gemini 3.5 Flash
Design Arena: UI components12691163Gemini 3.5 Flash
Design Arena: game dev12631178Gemini 3.5 Flash
Design Arena: data viz12361204Gemini 3.5 Flash
Design Arena: 3D12431060Gemini 3.5 Flash
Design Arena: all code categories12661170Gemini 3.5 Flash
Design Arena: SVG12531149Gemini 3.5 Flash
Design Arena: ASCII art12541119Gemini 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 index282
General benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-5.1Leader
Public Benefits Bench (Vals AI)59.5%Not measuredOnly Gemini 3.5 Flash measured
SAGE (Vals AI)49.9%43.2%Gemini 3.5 Flash
MedScribe (Vals AI)76.6%88.1%GPT-5.1
Vals Multimodal Index62.9%Not measuredOnly Gemini 3.5 Flash measured
IFBench76.3%72.9%Gemini 3.5 Flash
Long context reasoning (AA-LCR)74.3%80.0%GPT-5.1
DTBench94.7%90.1%Gemini 3.5 Flash
LMCA47.1%43.9%Gemini 3.5 Flash
CL-benchNot measured23.7%Only GPT-5.1 measured
Surface Evolver Bench58.1%Not measuredOnly Gemini 3.5 Flash measured
CL-bench LifeNot measured17.3%Only GPT-5.1 measured
LMArena Text14821443Gemini 3.5 Flash
LMArena Text: instruction following14671443Gemini 3.5 Flash
LMArena Text: creative writing14701427Gemini 3.5 Flash
LMArena Vision13081250Gemini 3.5 Flash
LMArena Text: English14811451Gemini 3.5 Flash
LMArena Text: non-English14751431Gemini 3.5 Flash
LMArena Text: Chinese15271495Gemini 3.5 Flash
LMArena Text: German14941438Gemini 3.5 Flash
LMArena Text: Japanese14861453Gemini 3.5 Flash
LMArena Text: Korean14481401Gemini 3.5 Flash
LMArena Text: French14901450Gemini 3.5 Flash
LMArena Text: Spanish14801433Gemini 3.5 Flash
LMArena Text: Russian14931435Gemini 3.5 Flash
LMArena Text: Polish15161440Gemini 3.5 Flash
LMArena Text: multi-turn14811450Gemini 3.5 Flash
LMArena Text: longer queries14831448Gemini 3.5 Flash
LMArena Text: writing and language14781428Gemini 3.5 Flash
LMArena Text: entertainment and media14591415Gemini 3.5 Flash
LMArena Vision: English13051252Gemini 3.5 Flash
LMArena Vision: Chinese13771270Gemini 3.5 Flash
LMArena Vision: reading text13171255Gemini 3.5 Flash
LMArena Vision: humor13211263Gemini 3.5 Flash
LMArena Vision: captioningNot measured1252Only GPT-5.1 measured
LMArena Vision: recognizing thingsNot measured1232Only GPT-5.1 measured
LMArena Vision: creative writing13011266Gemini 3.5 Flash
LMArena Document14631403Gemini 3.5 Flash
Neither model has a result on the other 9 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Gemini 3.5 Flash and GPT-5.1
BenchmarkGemini 3.5 FlashGPT-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

Gemini 3.5 Flash$0.0060Fits in one request
GPT-5.1$0.0063Fits in one request

Gemini 3.5 Flash costs less

Repository review

50K input + 3K output tokens

Gemini 3.5 Flash$0.102Fits in one request
GPT-5.1$0.092Fits in one request

GPT-5.1 costs less

Agent loop

200K input + 10K output tokens

Gemini 3.5 Flash$0.390Fits 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 Gemini 3.5 Flash and GPT-5.1
SpecificationGoogle Gemini 3.5 FlashOpenAI GPT-5.1
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 19, 2026November 13, 2025
Context window1.05M400K
Input $/Mtok$1.50$1.25
Output $/Mtok$9.00$10.00
Coding index39.840.4
Independent measurements behind it43
Cost per solved task$1.21$1.02
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash better than GPT-5.1 for coding?

Gemini 3.5 Flash and GPT-5.1 are level for coding, 39.8 against 40.4 on the Vibe Coding Index, so price and context decide. 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 400K tokens). Pick GPT-5.1 for a lower cost per solved task ($1.02 against $1.21) and work measured by LegalBench (Vals AI) or TaxEval (Vals AI), where it leads.

Which is cheaper, Gemini 3.5 Flash or GPT-5.1?

Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; GPT-5.1 costs $1.25 and $10.00. Per solved SWE-bench Verified task, Gemini 3.5 Flash costs $1.21 and GPT-5.1 $1.02.

Which has the bigger context window, Gemini 3.5 Flash or GPT-5.1?

Gemini 3.5 Flash, with 1.05M tokens against 400K.

How many benchmarks is the Gemini 3.5 Flash vs GPT-5.1 comparison based on?

83 benchmarks have a result for both models as of October 22, 2026. Gemini 3.5 Flash's coding index rests on 4 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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