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Gemini 3.5 Flash vs GPT-5.6 Terra

GPT-5.6 Terra leads Gemini 3.5 Flash on coding, 63.9 to 39.8 on the Vibe Coding Index, and Gemini 3.5 Flash costs 1.3x less per output token ($9.00 vs $12.00 per million). Updated October 22, 2026; 110 benchmarks have a result for both.

Replace Gemini 3.5 Flash Replace GPT-5.6 Terra
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
63
GPT-5.6 TerraOpenAI
Coding
63.9
Overall
68.1
Output $/M
$12.00
47
vs boards won of 110 shared

Gemini 3.5 Flash or GPT-5.6 Terra: which to pick

Pick GPT-5.6 Terra for coding: it scores 63.9 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash.

Pick Gemini 3.5 Flash for output tokens 1.3x cheaper ($9.00 vs $12.00 per million) and work measured by LiveCodeBench (Vals AI) or LMArena Text: coding, where it leads.

Model AGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved taskModel BGPT-5.6 TerraOpenAI63.9/1006 independent benchmarks$0.42 per solved task
Shared results
110
Gemini 3.5 Flash only
2
GPT-5.6 Terra only
17
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-5.6 Terra 63.9 from 6 benchmarks.
Widest category
Math, 20.6 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Gemini 3.5 Flash 26.8% against GPT-5.6 Terra 70.7%, 43.9 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash $9.00 against GPT-5.6 Terra $12.00 per million output tokens, 1.3x apart.
Context window
Gemini 3.5 Flash takes 1.05M tokens, GPT-5.6 Terra 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-5.6 TerraTies
Coding415
Intelligence02
Agentic work96
Reasoning78
Math24
Knowledge93
Web design62
General267
All shared boards6347
CodingLike-for-likeSix of these boards feed the Vibe Coding Index415
Coding benchmarks for Gemini 3.5 Flash and GPT-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
LiveBench codingNot measured86.2%Only GPT-5.6 Terra measured
LMArena WebDev14991522GPT-5.6 Terra
AA Coding IndexNot measured76.7Only GPT-5.6 Terra measured
LiveCodeBench (Vals AI)87.6%85.9%Gemini 3.5 Flash
SWE-bench Verified (Vals AI)78.8%95.4%GPT-5.6 Terra
Terminal-Bench 4 (Vals AI)6.1%22.7%GPT-5.6 Terra
Vibe Code Bench (Vals AI)48.7%74.6%GPT-5.6 Terra
Code migration (Vals AI)26.8%47.8%GPT-5.6 Terra
ProgramBench (Vals AI)0.0%0.5%GPT-5.6 Terra
IOI (Vals AI)Not measured87.6%Only GPT-5.6 Terra measured
Terminal-Bench 2.1 (Vals AI)74.2%77.5%GPT-5.6 Terra
Vibe Code Bench 1-100 (Vals AI)Not measured14.8%Only GPT-5.6 Terra measured
SkillsBench (Vals AI)52.7%58.9%GPT-5.6 Terra
CyberBench (Vals AI)Not measured72.1%Only GPT-5.6 Terra measured
SciCode53.9%55.0%GPT-5.6 Terra
Terminal-Bench Hard (Artificial Analysis run)46.2%62.9%GPT-5.6 Terra
FrontierCodeNot measured41.3%Only GPT-5.6 Terra measured
WeirdML62.6%78.3%GPT-5.6 Terra
ALE-Bench911.01951.4GPT-5.6 Terra
LMArena Text: coding14931485Gemini 3.5 Flash
LMArena Text: software and IT14941482Gemini 3.5 Flash
LMArena WebDev: React14951513GPT-5.6 Terra
LMArena WebDev: HTML15221526GPT-5.6 Terra
LMArena WebDev: from an image15041541GPT-5.6 Terra
SciCode12.3%10.8%Gemini 3.5 Flash
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-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
AA Intelligence Index33.642.1GPT-5.6 Terra
Epoch Capabilities Index154.9160.1GPT-5.6 Terra
Agentic workLike-for-likePublic boards, shown as published, kept out of the index96
Agentic work benchmarks for Gemini 3.5 Flash and GPT-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
AA Agentic IndexNot measured43.2Only GPT-5.6 Terra measured
Design Arena: agents building web apps12021120Gemini 3.5 Flash
Design Arena: agents building full-stack apps11971061Gemini 3.5 Flash
Design Arena: agents building mobile apps11741111Gemini 3.5 Flash
Design Arena: agents building Android apps11851062Gemini 3.5 Flash
Design Arena: agents building Godot games1098Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building games11801083Gemini 3.5 Flash
Design Arena: HTML slides10931058Gemini 3.5 Flash
Design Arena: PowerPoint slides11541105Gemini 3.5 Flash
LiveBench researchNot measured60.4%Only GPT-5.6 Terra measured
LiveBench browserNot measured84.0%Only GPT-5.6 Terra measured
LiveBench long agenticNot measured48.4%Only GPT-5.6 Terra measured
SREBench (Vals AI)Not measured9.5%Only GPT-5.6 Terra measured
Finance Agent (Vals AI)57.9%54.4%Gemini 3.5 Flash
Tax Agent Bench (Vals AI)21.6%30.0%GPT-5.6 Terra
Legal Research Bench (Vals AI)30.8%41.4%GPT-5.6 Terra
Excel Modeling Benchmark (Vals AI)63.5%66.2%GPT-5.6 Terra
Terminal-Bench-Science (Vals AI)5.7%10.0%GPT-5.6 Terra
τ²-Bench Telecom95.6%86.3%Gemini 3.5 Flash
APEX-Agents27.5%58.2%GPT-5.6 Terra
BALROGNot measured53.2%Only GPT-5.6 Terra measured
Vending-Bench 2$5,396$7,343GPT-5.6 Terra
Neither model has a result on the other 19 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index78
Reasoning benchmarks for Gemini 3.5 Flash and GPT-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
GPQA Diamond92.7%90.9%Gemini 3.5 Flash
LiveBench reasoningNot measured90.6%Only GPT-5.6 Terra measured
MMMU Pro (Vals AI)88.3%86.5%Gemini 3.5 Flash
GPQA Diamond (Artificial Analysis run)92.2%92.5%GPT-5.6 Terra
Humanity's Last Exam (Artificial Analysis run)42.7%42.9%GPT-5.6 Terra
GPQA Diamond (Epoch AI run)92.8%93.3%GPT-5.6 Terra
ARC-AGI92.5%96.5%GPT-5.6 Terra
ARC-AGI-272.1%83.9%GPT-5.6 Terra
SimpleBench76.7%48.9%Gemini 3.5 Flash
Chess puzzles45.0%47.0%GPT-5.6 Terra
Mystery game puzzles32.0%35.0%GPT-5.6 Terra
EBR-bench4.8%Not measuredOnly Gemini 3.5 Flash measured
LMArena Text: hard prompts14881469Gemini 3.5 Flash
LMArena Text: expert14951496GPT-5.6 Terra
LMArena Text: hard prompts in English14831465Gemini 3.5 Flash
LMArena Vision: diagrams13231295Gemini 3.5 Flash
LMArena Vision: homework13301312Gemini 3.5 Flash
Kagi LLM BenchmarkNot measured51.3%Only GPT-5.6 Terra 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-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
OTIS Mock AIME95.6%99.7%GPT-5.6 Terra
FrontierMath, tiers 1 to 362.8%86.0%GPT-5.6 Terra
FrontierMath, tier 426.8%70.7%GPT-5.6 Terra
ProofBench31.0%74.0%GPT-5.6 Terra
LMArena Text: math15041465Gemini 3.5 Flash
LMArena Text: mathematical work14951478Gemini 3.5 Flash
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index93
Knowledge benchmarks for Gemini 3.5 Flash and GPT-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
MMLU Pro89.5%86.7%Gemini 3.5 Flash
LegalBench (Vals AI)83.6%85.1%GPT-5.6 Terra
CorpFin (Vals AI)64.7%65.3%GPT-5.6 Terra
TaxEval (Vals AI)74.4%76.2%GPT-5.6 Terra
MortgageTax (Vals AI)68.1%67.3%Gemini 3.5 Flash
MedCode (Vals AI)55.8%43.4%Gemini 3.5 Flash
SimpleQA Verified66.2%43.2%Gemini 3.5 Flash
LMArena Text: science14951452Gemini 3.5 Flash
LMArena Text: medicine and healthcare14831430Gemini 3.5 Flash
LMArena Text: legal and government14881461Gemini 3.5 Flash
LMArena Text: business and finance14671448Gemini 3.5 Flash
FACTS Benchmark Suite63.1%52.0%Gemini 3.5 Flash
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index62
Web design benchmarks for Gemini 3.5 Flash and GPT-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
Design Arena: websites12671268GPT-5.6 Terra
Design Arena: UI components12691256Gemini 3.5 Flash
Design Arena: game dev12631229Gemini 3.5 Flash
Design Arena: data viz12361240GPT-5.6 Terra
Design Arena: 3D12431134Gemini 3.5 Flash
Design Arena: all code categories12661241Gemini 3.5 Flash
Design Arena: SVG12531219Gemini 3.5 Flash
Design Arena: ASCII art12541177Gemini 3.5 Flash
LiveBench designNot measured76.0%Only GPT-5.6 Terra measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index267
General benchmarks for Gemini 3.5 Flash and GPT-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
LiveBench data analysisNot measured79.3%Only GPT-5.6 Terra measured
Public Benefits Bench (Vals AI)59.5%62.4%GPT-5.6 Terra
SAGE (Vals AI)49.9%47.0%Gemini 3.5 Flash
MedScribe (Vals AI)76.6%82.9%GPT-5.6 Terra
Vals Multimodal Index62.9%65.1%GPT-5.6 Terra
IFBench76.3%71.2%Gemini 3.5 Flash
Long context reasoning (AA-LCR)74.3%83.0%GPT-5.6 Terra
DTBench94.7%93.3%Gemini 3.5 Flash
LMCA47.1%54.9%GPT-5.6 Terra
Surface Evolver Bench58.1%83.8%GPT-5.6 Terra
Furniture assemblyNot measured54.2%Only GPT-5.6 Terra measured
LMArena Text14821448Gemini 3.5 Flash
LMArena Text: instruction following14671456Gemini 3.5 Flash
LMArena Text: creative writing14701413Gemini 3.5 Flash
LMArena Vision13081271Gemini 3.5 Flash
LMArena Text: English14811449Gemini 3.5 Flash
LMArena Text: non-English14751441Gemini 3.5 Flash
LMArena Text: Chinese15271514Gemini 3.5 Flash
LMArena Text: German14941460Gemini 3.5 Flash
LMArena Text: Japanese14861454Gemini 3.5 Flash
LMArena Text: Korean14481427Gemini 3.5 Flash
LMArena Text: French14901466Gemini 3.5 Flash
LMArena Text: Spanish14801451Gemini 3.5 Flash
LMArena Text: Russian14931452Gemini 3.5 Flash
LMArena Text: Polish15161446Gemini 3.5 Flash
LMArena Text: multi-turn14811453Gemini 3.5 Flash
LMArena Text: longer queries14831454Gemini 3.5 Flash
LMArena Text: writing and language14781431Gemini 3.5 Flash
LMArena Text: entertainment and media14591418Gemini 3.5 Flash
LMArena Vision: English13051272Gemini 3.5 Flash
LMArena Vision: Chinese13771337Gemini 3.5 Flash
LMArena Vision: reading text13171278Gemini 3.5 Flash
LMArena Vision: humor13211236Gemini 3.5 Flash
LMArena Vision: creative writing13011248Gemini 3.5 Flash
LMArena Document14631472GPT-5.6 Terra
Neither model has a result on the other 11 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-5.6 Terra
BenchmarkGemini 3.5 FlashGPT-5.6 TerraLeader
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-5.6 Terra$0.0080Fits 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-5.6 Terra$0.136Fits 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-5.6 Terra$0.520Fits 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-5.6 Terra
SpecificationGoogle Gemini 3.5 FlashOpenAI GPT-5.6 Terra
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 19, 2026July 9, 2026
Context window1.05M1.05M
Input $/Mtok$1.50$2.00
Output $/Mtok$9.00$12.00
Coding index39.863.9
Independent measurements behind it46
Cost per solved task$1.21$0.42
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash better than GPT-5.6 Terra for coding?

Pick GPT-5.6 Terra for coding: it scores 63.9 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash. Pick Gemini 3.5 Flash for output tokens 1.3x cheaper ($9.00 vs $12.00 per million) and work measured by LiveCodeBench (Vals AI) or LMArena Text: coding, where it leads.

Which is cheaper, Gemini 3.5 Flash or GPT-5.6 Terra?

Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; GPT-5.6 Terra costs $2.00 and $12.00. Per solved SWE-bench Verified task, Gemini 3.5 Flash costs $1.21 and GPT-5.6 Terra $0.42.

Which has the bigger context window, Gemini 3.5 Flash or GPT-5.6 Terra?

GPT-5.6 Terra, with 1.05M tokens against 1.05M.

How many benchmarks is the Gemini 3.5 Flash vs GPT-5.6 Terra comparison based on?

110 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-5.6 Terra's on 6. Where only one model has a result, the page says so instead of naming a winner.

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