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Gemini 2.5 Flash vs GPT-5.1

Updated October 21, 2026. 68 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-5.1
Gemini 2.5 FlashGoogle
Coding
28.7
Overall
15.5
Output $/M
$2.50
4
GPT-5.1OpenAI
Coding
53.3
Overall
24.7
Output $/M
$10.00
64
vs boards won of 68 shared

Decision reading

Pick GPT-5.1 for coding: it scores 53.3 on the Vibe Coding Index against 28.7 for Gemini 2.5 Flash.

Pick Gemini 2.5 Flash when output tokens cost 4.0x less, or when a solved task costs $0.466 against $1.02.

Model AGemini 2.5 FlashGoogle28.7/1001 independent benchmark$0.466 per solved taskModel BGPT-5.1OpenAI53.3/1002 independent benchmarks$1.02 per solved task
Shared results
68
Gemini 2.5 Flash only
1
GPT-5.1 only
32
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-5.1 53.3 from 2 benchmarks.
Widest category
Agentic work, 28.0 points apart on average over 2 shared benchmarks.
Widest single gap
τ²-Bench Telecom: Gemini 2.5 Flash 31.6% against GPT-5.1 81.9%, 50.3 points apart on a 0 to 100 scale.
Output price
Gemini 2.5 Flash $2.50 against GPT-5.1 $10.00 per million output tokens, 4.0x apart.
Context window
Gemini 2.5 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 2.5 FlashBarsGPT-5.1Ties
Coding06
Intelligence02
Agentic work02
Reasoning010
Math04
Knowledge06
Web design07
General427
All shared boards464
CodingLike-for-likeFour of these boards feed the Vibe Coding Index06
Coding benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
SWE-bench Verified28.7%66.0%GPT-5.1
LMArena WebDevNot measured1396Only GPT-5.1 measured
AA Coding IndexNot measured49.4Only GPT-5.1 measured
LiveCodeBench (Vals AI)Not measured86.5%Only GPT-5.1 measured
SWE-bench Verified (Vals AI)Not measured69.8%Only GPT-5.1 measured
Vibe Code Bench (Vals AI)Not measured24.6%Only GPT-5.1 measured
LiveCodeBench (Artificial Analysis run)69.5%86.8%GPT-5.1
Terminal-Bench Hard (Artificial Analysis run)13.6%45.5%GPT-5.1
Terminal-Bench17.1%47.6%GPT-5.1
GSO-BenchNot measured13.7%Only GPT-5.1 measured
WeirdMLNot measured60.8%Only GPT-5.1 measured
LMArena Text: coding14231453GPT-5.1
LMArena Text: software and IT14251454GPT-5.1
LMArena WebDev: ReactNot measured1307Only GPT-5.1 measured
LMArena WebDev: HTMLNot measured1405Only GPT-5.1 measured
LMArena WebDev: from an imageNot measured1421Only GPT-5.1 measured
Neither model has a result on the other 22 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
AA Intelligence Index15.524.7GPT-5.1
Epoch Capabilities Index142.9149.8GPT-5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index02
Agentic work benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
τ²-Bench Telecom31.6%81.9%GPT-5.1
BALROG33.5%Not measuredOnly Gemini 2.5 Flash measured
DeepResearch BenchNot measured42.8%Only GPT-5.1 measured
Vending-Bench 2$549$1,473GPT-5.1
Neither model has a result on the other 35 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index010
Reasoning benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
GPQA DiamondNot measured86.6%Only GPT-5.1 measured
MMMU Pro (Vals AI)Not measured83.2%Only GPT-5.1 measured
GPQA Diamond (Artificial Analysis run)79.0%87.3%GPT-5.1
Humanity's Last Exam (Artificial Analysis run)12.1%28.5%GPT-5.1
GPQA Diamond (Epoch AI run)Not measured87.6%Only GPT-5.1 measured
ARC-AGI33.3%72.8%GPT-5.1
ARC-AGI-22.5%17.6%GPT-5.1
SimpleBench41.2%53.2%GPT-5.1
Chess puzzlesNot measured42.0%Only GPT-5.1 measured
Mystery game puzzlesNot measured19.0%Only GPT-5.1 measured
VPCTNot measured58.7%Only GPT-5.1 measured
LMArena Text: hard prompts14221457GPT-5.1
LMArena Text: expert14261470GPT-5.1
LMArena Text: hard prompts in English14201462GPT-5.1
LMArena Vision: diagrams12451264GPT-5.1
LMArena Vision: homework12441272GPT-5.1
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index04
Math benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
AIMENot measured93.3%Only GPT-5.1 measured
MGSM (Vals AI)Not measured93.0%Only GPT-5.1 measured
AA Math Index73.394.0GPT-5.1
AIME 2025 (Artificial Analysis run)73.3%94.0%GPT-5.1
OTIS Mock AIMENot measured88.6%Only GPT-5.1 measured
LMArena Text: math14111446GPT-5.1
LMArena Text: mathematical work14221449GPT-5.1
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index06
Knowledge benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
MMLU ProNot measured86.4%Only GPT-5.1 measured
LegalBench (Vals AI)Not measured85.7%Only GPT-5.1 measured
CaseLaw (Vals AI)Not measured73.4%Only GPT-5.1 measured
CorpFin (Vals AI)Not measured63.8%Only GPT-5.1 measured
TaxEval (Vals AI)Not measured74.9%Only GPT-5.1 measured
MortgageTax (Vals AI)Not measured61.4%Only GPT-5.1 measured
MedQA (Vals AI)Not measured96.4%Only GPT-5.1 measured
MedCode (Vals AI)40.4%52.7%GPT-5.1
MMLU Pro (Artificial Analysis run)83.2%87.0%GPT-5.1
SimpleQA VerifiedNot measured48.0%Only GPT-5.1 measured
LMArena Text: science14331459GPT-5.1
LMArena Text: medicine and healthcare14281456GPT-5.1
LMArena Text: legal and government14301459GPT-5.1
LMArena Text: business and finance14041431GPT-5.1
Neither model has a result on the other 3 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-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
Design Arena: websites10741187GPT-5.1
Design Arena: UI components10051166GPT-5.1
Design Arena: game dev10051179GPT-5.1
Design Arena: data viz10601204GPT-5.1
Design Arena: 3D10211061GPT-5.1
Design Arena: all code categories10591171GPT-5.1
Design Arena: SVG10181149GPT-5.1
Design Arena: ASCII artNot measured1118Only GPT-5.1 measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index427
General benchmarks for Gemini 2.5 Flash and GPT-5.1
BenchmarkGemini 2.5 FlashGPT-5.1Leader
SAGE (Vals AI)44.8%43.2%Gemini 2.5 Flash
MedScribe (Vals AI)83.0%88.1%GPT-5.1
IFBench50.3%72.9%GPT-5.1
Long context reasoning (AA-LCR)65.3%80.0%GPT-5.1
DTBench76.5%90.1%GPT-5.1
LMCA27.5%43.9%GPT-5.1
CL-benchNot measured23.7%Only GPT-5.1 measured
CL-bench LifeNot measured17.3%Only GPT-5.1 measured
LMArena Text14171443GPT-5.1
LMArena Text: instruction following14051443GPT-5.1
LMArena Text: creative writing14001427GPT-5.1
LMArena Vision12351250GPT-5.1
LMArena Text: English14181451GPT-5.1
LMArena Text: non-English14091431GPT-5.1
LMArena Text: Chinese14491495GPT-5.1
LMArena Text: German14171438GPT-5.1
LMArena Text: Japanese13961453GPT-5.1
LMArena Text: Korean13851401GPT-5.1
LMArena Text: French14321450GPT-5.1
LMArena Text: Spanish14221433GPT-5.1
LMArena Text: Russian14151435GPT-5.1
LMArena Text: Polish14131440GPT-5.1
LMArena Text: multi-turn14081450GPT-5.1
LMArena Text: longer queries14191448GPT-5.1
LMArena Text: writing and language14051428GPT-5.1
LMArena Text: entertainment and media13931415GPT-5.1
LMArena Vision: English12391252GPT-5.1
LMArena Vision: Chinese12841270Gemini 2.5 Flash
LMArena Vision: reading text12371255GPT-5.1
LMArena Vision: humor12251263GPT-5.1
LMArena Vision: captioning12771252Gemini 2.5 Flash
LMArena Vision: recognizing things12521232Gemini 2.5 Flash
LMArena Vision: creative writing12411266GPT-5.1
LMArena DocumentNot measured1403Only GPT-5.1 measured
Neither model has a result on the other 12 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-5.1
BenchmarkGemini 2.5 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 2.5 Flash$0.0015Fits in one request
GPT-5.1$0.0063Fits 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-5.1$0.092Fits 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-5.1$0.350Fits 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-5.1
SpecificationGoogle Gemini 2.5 FlashOpenAI GPT-5.1
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedJune 17, 2025November 13, 2025
Context window1.05M400K
Input $/Mtok$0.30$1.25
Output $/Mtok$2.50$10.00
Coding index28.753.3
Independent measurements behind it12
Cost per solved task$0.466$1.02
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 2.5 Flash better than GPT-5.1 for coding?

Pick GPT-5.1 for coding: it scores 53.3 on the Vibe Coding Index against 28.7 for Gemini 2.5 Flash. Pick Gemini 2.5 Flash when output tokens cost 4.0x less, or when a solved task costs $0.466 against $1.02.

Which is cheaper, Gemini 2.5 Flash or GPT-5.1?

Gemini 2.5 Flash costs $0.30 per million input tokens and $2.50 per million output tokens; GPT-5.1 costs $1.25 and $10.00. Per solved SWE-bench Verified task, Gemini 2.5 Flash costs $0.466 and GPT-5.1 $1.02.

Which has the bigger context window, Gemini 2.5 Flash or GPT-5.1?

Gemini 2.5 Flash, with 1.05M tokens against 400K.

How many benchmarks is the Gemini 2.5 Flash vs GPT-5.1 comparison based on?

68 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-5.1's on 2. Where only one model has a result, the page says so instead of naming a winner.

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