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Gemini 2.5 Flash vs GPT-5.5

Updated October 21, 2026. 62 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Gemini 2.5 Flash Replace GPT-5.5
Gemini 2.5 FlashGoogle
Coding
28.7
Overall
15.5
Output $/M
$2.50
1
GPT-5.5OpenAI
Coding
67.8
Overall
38.4
Output $/M
$30.00
61
vs boards won of 62 shared

Decision reading

Pick GPT-5.5 for coding: it scores 67.8 on the Vibe Coding Index against 28.7 for Gemini 2.5 Flash.

Pick Gemini 2.5 Flash when output tokens cost 12.0x less, or when a solved task costs $0.466 against $1.65.

Model AGemini 2.5 FlashGoogle28.7/1001 independent benchmark$0.466 per solved taskModel BGPT-5.5OpenAI67.8/1002 independent benchmarks$1.65 per solved task
Shared results
62
Gemini 2.5 Flash only
7
GPT-5.5 only
70
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
Gemini 2.5 Flash 28.7 from 1 benchmark, GPT-5.5 67.8 from 2 benchmarks.
Widest category
Agentic work, 52.9 points apart on average over 2 shared benchmarks.
Widest single gap
ARC-AGI-2: Gemini 2.5 Flash 2.5% against GPT-5.5 85.0%, 82.5 points apart on a 0 to 100 scale.
Output price
Gemini 2.5 Flash $2.50 against GPT-5.5 $30.00 per million output tokens, 12.0x apart.
Context window
Gemini 2.5 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 2.5 FlashBarsGPT-5.5Ties
Coding04
Intelligence02
Agentic work02
Reasoning010
Math02
Knowledge05
Web design07
General129
All shared boards161
CodingLike-for-likeFour of these boards feed the Vibe Coding Index04
Coding benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
SWE-bench Verified28.7%Not measuredOnly Gemini 2.5 Flash measured
LiveBench codingNot measured85.1%Only GPT-5.5 measured
LMArena WebDevNot measured1513Only GPT-5.5 measured
AA Coding IndexNot measured74.9Only GPT-5.5 measured
LiveCodeBench (Vals AI)Not measured85.3%Only GPT-5.5 measured
SWE-bench Verified (Vals AI)Not measured82.6%Only GPT-5.5 measured
Vibe Code Bench (Vals AI)Not measured69.8%Only GPT-5.5 measured
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
LiveCodeBench (Artificial Analysis run)69.5%Not measuredOnly Gemini 2.5 Flash measured
SciCodeNot measured56.1%Only GPT-5.5 measured
Terminal-Bench Hard (Artificial Analysis run)13.6%60.6%GPT-5.5
Terminal-Bench17.1%84.7%GPT-5.5
FrontierCodeNot measured43.0%Only GPT-5.5 measured
GSO-BenchNot measured40.2%Only GPT-5.5 measured
WeirdMLNot measured84.9%Only GPT-5.5 measured
MirrorCodeNot measured10.0%Only GPT-5.5 measured
ALE-BenchNot measured1943.0Only GPT-5.5 measured
LMArena Text: coding14231494GPT-5.5
LMArena Text: software and IT14251493GPT-5.5
LMArena WebDev: ReactNot measured1506Only GPT-5.5 measured
LMArena WebDev: HTMLNot measured1543Only GPT-5.5 measured
LMArena WebDev: from an imageNot measured1532Only GPT-5.5 measured
Neither model has a result on the other 13 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
AA Intelligence Index15.538.4GPT-5.5
Epoch Capabilities Index142.9159.7GPT-5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index02
Agentic work benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
AA Agentic IndexNot measured36.4Only GPT-5.5 measured
Design Arena: agents building web appsNot measured1117Only GPT-5.5 measured
Design Arena: agents building full-stack appsNot measured1089Only GPT-5.5 measured
Design Arena: agents building mobile appsNot measured1143Only GPT-5.5 measured
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 Telecom31.6%93.9%GPT-5.5
APEX-AgentsNot measured55.1%Only GPT-5.5 measured
Remote Labor IndexNot measured6.3%Only GPT-5.5 measured
OSWorld 2.0Not measured13.0%Only GPT-5.5 measured
BALROG33.5%Not measuredOnly Gemini 2.5 Flash measured
DeepResearch BenchNot measured54.0%Only GPT-5.5 measured
PostTrainBenchNot measured27.2%Only GPT-5.5 measured
Vending-Bench 2$549$7,524GPT-5.5
Neither model has a result on the other 13 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index010
Reasoning benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
GPQA DiamondNot measured93.2%Only GPT-5.5 measured
LiveBench reasoningNot measured89.7%Only GPT-5.5 measured
MMMU Pro (Vals AI)Not measured88.3%Only GPT-5.5 measured
GPQA Diamond (Artificial Analysis run)79.0%93.5%GPT-5.5
Humanity's Last Exam (Artificial Analysis run)12.1%45.8%GPT-5.5
GPQA Diamond (Epoch AI run)Not measured90.7%Only GPT-5.5 measured
ARC-AGI33.3%95.0%GPT-5.5
ARC-AGI-22.5%85.0%GPT-5.5
SimpleBench41.2%69.0%GPT-5.5
Chess puzzlesNot measured63.0%Only GPT-5.5 measured
Mystery game puzzlesNot measured56.0%Only GPT-5.5 measured
EBR-benchNot measured34.3%Only GPT-5.5 measured
LMArena Text: hard prompts14221489GPT-5.5
LMArena Text: expert14261507GPT-5.5
LMArena Text: hard prompts in English14201483GPT-5.5
LMArena Vision: diagrams12451325GPT-5.5
LMArena Vision: homework12441332GPT-5.5
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index02
Math benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
AA Math Index73.3Not measuredOnly Gemini 2.5 Flash measured
AIME 2025 (Artificial Analysis run)73.3%Not measuredOnly Gemini 2.5 Flash measured
OTIS Mock AIMENot measured84.4%Only GPT-5.5 measured
FrontierMath, tiers 1 to 3Not measured85.3%Only GPT-5.5 measured
FrontierMath, tier 4Not measured72.5%Only GPT-5.5 measured
ProofBenchNot measured50.0%Only GPT-5.5 measured
LMArena Text: math14111487GPT-5.5
LMArena Text: mathematical work14221496GPT-5.5
Neither model has a result on the other 5 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index05
Knowledge benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
MMLU ProNot measured88.1%Only GPT-5.5 measured
LegalBench (Vals AI)Not measured86.5%Only GPT-5.5 measured
CaseLaw (Vals AI)Not measured66.2%Only GPT-5.5 measured
CorpFin (Vals AI)Not measured68.4%Only GPT-5.5 measured
TaxEval (Vals AI)Not measured75.0%Only GPT-5.5 measured
MortgageTax (Vals AI)Not measured68.8%Only GPT-5.5 measured
MedCode (Vals AI)40.4%49.1%GPT-5.5
MMLU Pro (Artificial Analysis run)83.2%Not measuredOnly Gemini 2.5 Flash measured
SimpleQA VerifiedNot measured63.0%Only GPT-5.5 measured
LMArena Text: science14331485GPT-5.5
LMArena Text: medicine and healthcare14281465GPT-5.5
LMArena Text: legal and government14301491GPT-5.5
LMArena Text: business and finance14041478GPT-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 index07
Web design benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-5.5Leader
Design Arena: websites10741256GPT-5.5
Design Arena: UI components10051260GPT-5.5
Design Arena: game dev10051294GPT-5.5
Design Arena: data viz10601265GPT-5.5
Design Arena: 3D10211198GPT-5.5
Design Arena: all code categories10591260GPT-5.5
Design Arena: SVG10181234GPT-5.5
Design Arena: ASCII artNot measured1254Only GPT-5.5 measured
LiveBench designNot measured70.3%Only GPT-5.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index129
General benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 FlashGPT-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)44.8%51.5%GPT-5.5
MedScribe (Vals AI)83.0%86.9%GPT-5.5
Vals Multimodal IndexNot measured68.1%Only GPT-5.5 measured
IFBench50.3%75.9%GPT-5.5
Long context reasoning (AA-LCR)65.3%84.3%GPT-5.5
DTBench76.5%96.0%GPT-5.5
LMCA27.5%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 Text14171471GPT-5.5
LMArena Text: instruction following14051478GPT-5.5
LMArena Text: creative writing14001455GPT-5.5
LMArena Vision12351297GPT-5.5
LMArena Text: English14181470GPT-5.5
LMArena Text: non-English14091467GPT-5.5
LMArena Text: Chinese14491534GPT-5.5
LMArena Text: German14171480GPT-5.5
LMArena Text: Japanese13961499GPT-5.5
LMArena Text: Korean13851460GPT-5.5
LMArena Text: French14321485GPT-5.5
LMArena Text: Spanish14221468GPT-5.5
LMArena Text: Russian14151473GPT-5.5
LMArena Text: Polish14131465GPT-5.5
LMArena Text: multi-turn14081476GPT-5.5
LMArena Text: longer queries14191484GPT-5.5
LMArena Text: writing and language14051466GPT-5.5
LMArena Text: entertainment and media13931449GPT-5.5
LMArena Vision: English12391292GPT-5.5
LMArena Vision: Chinese12841360GPT-5.5
LMArena Vision: reading text12371306GPT-5.5
LMArena Vision: humor12251293GPT-5.5
LMArena Vision: captioning1277Not measuredOnly Gemini 2.5 Flash measured
LMArena Vision: recognizing things12521231Gemini 2.5 Flash
LMArena Vision: creative writing12411301GPT-5.5
LMArena DocumentNot measured1486Only GPT-5.5 measured
Neither model has a result on the other 7 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Gemini 2.5 Flash and GPT-5.5
BenchmarkGemini 2.5 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 2.5 Flash$0.0015Fits in one request
GPT-5.5$0.020Fits in one request

Gemini 2.5 Flash costs less

Repository review

50K input + 3K output tokens

Gemini 2.5 Flash$0.022Fits in one request
GPT-5.5$0.340Fits in one request

Gemini 2.5 Flash costs less

Agent loop

200K input + 10K output tokens

Gemini 2.5 Flash$0.085Fits in one request
GPT-5.5$1.30Fits in one request

Gemini 2.5 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 2.5 Flash and GPT-5.5
SpecificationGoogle Gemini 2.5 FlashOpenAI GPT-5.5
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedJune 17, 2025April 24, 2026
Context window1.05M1.05M
Input $/Mtok$0.30$5.00
Output $/Mtok$2.50$30.00
Coding index28.767.8
Independent measurements behind it12
Cost per solved task$0.466$1.65
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 2.5 Flash better than GPT-5.5 for coding?

Pick GPT-5.5 for coding: it scores 67.8 on the Vibe Coding Index against 28.7 for Gemini 2.5 Flash. Pick Gemini 2.5 Flash when output tokens cost 12.0x less, or when a solved task costs $0.466 against $1.65.

Which is cheaper, Gemini 2.5 Flash or GPT-5.5?

Gemini 2.5 Flash costs $0.30 per million input tokens and $2.50 per million output tokens; GPT-5.5 costs $5.00 and $30.00. Per solved SWE-bench Verified task, Gemini 2.5 Flash costs $0.466 and GPT-5.5 $1.65.

Which has the bigger context window, Gemini 2.5 Flash or GPT-5.5?

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

How many benchmarks is the Gemini 2.5 Flash vs GPT-5.5 comparison based on?

62 benchmarks have a result for both models as of October 21, 2026. Gemini 2.5 Flash's coding index rests on 1 independent benchmark 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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