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Gemini 3.5 Flash vs GPT-5.5

GPT-5.5 leads Gemini 3.5 Flash on coding, 71.3 to 39.8 on the Vibe Coding Index, and Gemini 3.5 Flash costs 3.3x less per output token ($9.00 vs $30.00 per million). Updated October 22, 2026; 109 benchmarks have a result for both.

Replace Gemini 3.5 Flash Replace GPT-5.5
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
43
GPT-5.5OpenAI
Coding
71.3
Overall
69.2
Output $/M
$30.00
65
vs boards won of 109 shared, 1 tied

Gemini 3.5 Flash or GPT-5.5: which to pick

Pick GPT-5.5 for coding: it scores 71.3 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash.

Pick Gemini 3.5 Flash for output tokens 3.3x cheaper ($9.00 vs $30.00 per million) and a lower cost per solved task ($1.21 against $1.65).

Model AGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved taskModel BGPT-5.5OpenAI71.3/1005 independent benchmarks$1.65 per solved task
Shared results
109
Gemini 3.5 Flash only
3
GPT-5.5 only
25
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-5.5 71.3 from 5 benchmarks.
Widest category
Math, 16.9 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Gemini 3.5 Flash 26.8% against GPT-5.5 72.5%, 45.7 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash $9.00 against GPT-5.5 $30.00 per million output tokens, 3.3x apart.
Context window
Gemini 3.5 Flash takes 1.05M 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
CategoryGemini 3.5 FlashBarsGPT-5.5Ties
Coding215
Intelligence02
Agentic work96
Reasoning2131 tie
Math24
Knowledge57
Web design53
General1815
All shared boards43651 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index215
Coding benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
LiveBench codingNot measured85.1%Only GPT-5.5 measured
LMArena WebDev14991513GPT-5.5
AA Coding IndexNot measured74.9Only GPT-5.5 measured
LiveCodeBench (Vals AI)87.6%85.3%Gemini 3.5 Flash
SWE-bench Verified (Vals AI)78.8%82.6%GPT-5.5
Terminal-Bench 4 (Vals AI)6.1%Not measuredOnly Gemini 3.5 Flash measured
Vibe Code Bench (Vals AI)48.7%69.8%GPT-5.5
Code migration (Vals AI)26.8%45.2%GPT-5.5
ProgramBench (Vals AI)0.0%0.5%GPT-5.5
Terminal-Bench 2.1 (Vals AI)74.2%76.4%GPT-5.5
SkillsBench (Vals AI)52.7%62.5%GPT-5.5
SciCode53.9%56.1%GPT-5.5
Terminal-Bench Hard (Artificial Analysis run)46.2%60.6%GPT-5.5
Terminal-BenchNot measured84.7%Only GPT-5.5 measured
FrontierCodeNot measured43.0%Only GPT-5.5 measured
GSO-BenchNot measured40.2%Only GPT-5.5 measured
WeirdML62.6%84.9%GPT-5.5
MirrorCodeNot measured10.0%Only GPT-5.5 measured
ALE-Bench911.01943.0GPT-5.5
LMArena Text: coding14931494GPT-5.5
LMArena Text: software and IT14941493Gemini 3.5 Flash
LMArena WebDev: React14951506GPT-5.5
LMArena WebDev: HTML15221543GPT-5.5
LMArena WebDev: from an image15041532GPT-5.5
SciCode12.3%Not measuredOnly 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 Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
AA Intelligence Index33.638.4GPT-5.5
Epoch Capabilities Index154.9159.7GPT-5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index96
Agentic work benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
AA Agentic IndexNot measured36.4Only GPT-5.5 measured
Design Arena: agents building web apps12021117Gemini 3.5 Flash
Design Arena: agents building full-stack apps11971089Gemini 3.5 Flash
Design Arena: agents building mobile apps11741142Gemini 3.5 Flash
Design Arena: agents building Android apps11851164Gemini 3.5 Flash
Design Arena: agents building Godot games10981173GPT-5.5
Design Arena: agents building games11801179Gemini 3.5 Flash
Design Arena: HTML slides10931017Gemini 3.5 Flash
Design Arena: PowerPoint slides11541084Gemini 3.5 Flash
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)57.9%51.8%Gemini 3.5 Flash
Tax Agent Bench (Vals AI)21.6%21.8%GPT-5.5
Legal Research Bench (Vals AI)30.8%40.4%GPT-5.5
Excel Modeling Benchmark (Vals AI)63.5%64.5%GPT-5.5
Terminal-Bench-Science (Vals AI)5.7%Not measuredOnly Gemini 3.5 Flash measured
Time Horizon Index (Vals AI)Not measured8.3%Only GPT-5.5 measured
τ²-Bench Telecom95.6%93.9%Gemini 3.5 Flash
APEX-Agents27.5%55.1%GPT-5.5
Remote Labor IndexNot measured6.3%Only GPT-5.5 measured
OSWorld 2.0Not measured13.0%Only GPT-5.5 measured
DeepResearch BenchNot measured54.0%Only GPT-5.5 measured
PostTrainBenchNot measured27.2%Only GPT-5.5 measured
Vending-Bench 2$5,396$7,524GPT-5.5
Neither model has a result on the other 15 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index213
Reasoning benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
GPQA Diamond92.7%93.2%GPT-5.5
LiveBench reasoningNot measured89.7%Only GPT-5.5 measured
MMMU Pro (Vals AI)88.3%88.3%Tie
GPQA Diamond (Artificial Analysis run)92.2%93.5%GPT-5.5
Humanity's Last Exam (Artificial Analysis run)42.7%45.8%GPT-5.5
GPQA Diamond (Epoch AI run)92.8%90.7%Gemini 3.5 Flash
ARC-AGI92.5%95.0%GPT-5.5
ARC-AGI-272.1%85.0%GPT-5.5
SimpleBench76.7%69.0%Gemini 3.5 Flash
Chess puzzles45.0%63.0%GPT-5.5
Mystery game puzzles32.0%56.0%GPT-5.5
EBR-bench4.8%34.3%GPT-5.5
LMArena Text: hard prompts14881489GPT-5.5
LMArena Text: expert14951507GPT-5.5
LMArena Text: hard prompts in English14831483GPT-5.5
LMArena Vision: diagrams13231325GPT-5.5
LMArena Vision: homework13301332GPT-5.5
Kagi LLM BenchmarkNot measured88.8%Only GPT-5.5 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index24
Math benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
OTIS Mock AIME95.6%84.4%Gemini 3.5 Flash
FrontierMath, tiers 1 to 362.8%85.3%GPT-5.5
FrontierMath, tier 426.8%72.5%GPT-5.5
ProofBench31.0%50.0%GPT-5.5
LMArena Text: math15041487Gemini 3.5 Flash
LMArena Text: mathematical work14951496GPT-5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index57
Knowledge benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
MMLU Pro89.5%88.1%Gemini 3.5 Flash
LegalBench (Vals AI)83.6%86.5%GPT-5.5
CaseLaw (Vals AI)Not measured66.2%Only GPT-5.5 measured
CorpFin (Vals AI)64.7%68.4%GPT-5.5
TaxEval (Vals AI)74.4%75.0%GPT-5.5
MortgageTax (Vals AI)68.1%68.8%GPT-5.5
MedCode (Vals AI)55.8%49.1%Gemini 3.5 Flash
SimpleQA Verified66.2%63.0%Gemini 3.5 Flash
LMArena Text: science14951485Gemini 3.5 Flash
LMArena Text: medicine and healthcare14831465Gemini 3.5 Flash
LMArena Text: legal and government14881491GPT-5.5
LMArena Text: business and finance14671478GPT-5.5
FACTS Benchmark Suite63.1%66.7%GPT-5.5
Neither model has a result on the other 5 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index53
Web design benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
Design Arena: websites12671256Gemini 3.5 Flash
Design Arena: UI components12691257Gemini 3.5 Flash
Design Arena: game dev12631293GPT-5.5
Design Arena: data viz12361264GPT-5.5
Design Arena: 3D12431197Gemini 3.5 Flash
Design Arena: all code categories12661260Gemini 3.5 Flash
Design Arena: SVG12531234Gemini 3.5 Flash
Design Arena: ASCII art12541255GPT-5.5
LiveBench designNot measured70.3%Only GPT-5.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index1815
General benchmarks for Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-5.5Leader
LiveBench data analysisNot measured81.6%Only GPT-5.5 measured
Public Benefits Bench (Vals AI)59.5%60.9%GPT-5.5
SAGE (Vals AI)49.9%51.5%GPT-5.5
MedScribe (Vals AI)76.6%86.9%GPT-5.5
Vals Multimodal Index62.9%68.1%GPT-5.5
IFBench76.3%75.9%Gemini 3.5 Flash
Long context reasoning (AA-LCR)74.3%84.3%GPT-5.5
DTBench94.7%96.0%GPT-5.5
LMCA47.1%54.3%GPT-5.5
Surface Evolver Bench58.1%88.1%GPT-5.5
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 Text14821471Gemini 3.5 Flash
LMArena Text: instruction following14671478GPT-5.5
LMArena Text: creative writing14701455Gemini 3.5 Flash
LMArena Vision13081297Gemini 3.5 Flash
LMArena Text: English14811470Gemini 3.5 Flash
LMArena Text: non-English14751467Gemini 3.5 Flash
LMArena Text: Chinese15271534GPT-5.5
LMArena Text: German14941480Gemini 3.5 Flash
LMArena Text: Japanese14861499GPT-5.5
LMArena Text: Korean14481460GPT-5.5
LMArena Text: French14901485Gemini 3.5 Flash
LMArena Text: Spanish14801468Gemini 3.5 Flash
LMArena Text: Russian14931473Gemini 3.5 Flash
LMArena Text: Polish15161465Gemini 3.5 Flash
LMArena Text: multi-turn14811476Gemini 3.5 Flash
LMArena Text: longer queries14831484GPT-5.5
LMArena Text: writing and language14781466Gemini 3.5 Flash
LMArena Text: entertainment and media14591449Gemini 3.5 Flash
LMArena Vision: English13051292Gemini 3.5 Flash
LMArena Vision: Chinese13771360Gemini 3.5 Flash
LMArena Vision: reading text13171306Gemini 3.5 Flash
LMArena Vision: humor13211293Gemini 3.5 Flash
LMArena Vision: recognizing thingsNot measured1231Only GPT-5.5 measured
LMArena Vision: creative writing13011301GPT-5.5
LMArena Document14631486GPT-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 Gemini 3.5 Flash and GPT-5.5
BenchmarkGemini 3.5 FlashGPT-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

Gemini 3.5 Flash$0.0060Fits in one request
GPT-5.5$0.020Fits 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-5.5$0.340Fits in one request

Gemini 3.5 Flash costs less

Agent loop

200K input + 10K output tokens

Gemini 3.5 Flash$0.390Fits in one request
GPT-5.5$1.30Fits 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 Gemini 3.5 Flash and GPT-5.5
SpecificationGoogle Gemini 3.5 FlashOpenAI GPT-5.5
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 19, 2026April 24, 2026
Context window1.05M1.05M
Input $/Mtok$1.50$5.00
Output $/Mtok$9.00$30.00
Coding index39.871.3
Independent measurements behind it45
Cost per solved task$1.21$1.65
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash better than GPT-5.5 for coding?

Pick GPT-5.5 for coding: it scores 71.3 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash. Pick Gemini 3.5 Flash for output tokens 3.3x cheaper ($9.00 vs $30.00 per million) and a lower cost per solved task ($1.21 against $1.65).

Which is cheaper, Gemini 3.5 Flash or GPT-5.5?

Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; GPT-5.5 costs $5.00 and $30.00. Per solved SWE-bench Verified task, Gemini 3.5 Flash costs $1.21 and GPT-5.5 $1.65.

Which has the bigger context window, Gemini 3.5 Flash or GPT-5.5?

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

How many benchmarks is the Gemini 3.5 Flash vs GPT-5.5 comparison based on?

109 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-5.5's on 5. Where only one model has a result, the page says so instead of naming a winner.

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