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Gemini 3.5 Flash vs Grok 4.5

Grok 4.5 leads Gemini 3.5 Flash on coding, 58.6 to 39.8 on the Vibe Coding Index, and Grok 4.5 costs 1.5x less per output token ($6.00 vs $9.00 per million). Updated October 21, 2026; 105 benchmarks have a result for both.

Replace Gemini 3.5 Flash Replace Grok 4.5
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
61
Grok 4.5xAI
Coding
58.6
Overall
62.1
Output $/M
$6.00
40
vs boards won of 105 shared, 4 tied

Gemini 3.5 Flash or Grok 4.5: which to pick

Pick Grok 4.5 for coding: it scores 58.6 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash.

Pick Gemini 3.5 Flash for a larger context window (1.05M against 500K tokens) and work measured by LiveCodeBench (Vals AI) or Terminal-Bench 2.1 (Vals AI), where it leads.

Model AGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved taskModel BGrok 4.5xAI58.6/1006 independent benchmarks$0.62 per solved task
Shared results
105
Gemini 3.5 Flash only
7
Grok 4.5 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, Grok 4.5 58.6 from 6 benchmarks.
Widest category
Agentic work, 9.2 points apart on average over 14 shared benchmarks.
Widest single gap
APEX-Agents: Gemini 3.5 Flash 27.5% against Grok 4.5 56.2%, 28.7 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash $9.00 against Grok 4.5 $6.00 per million output tokens, 1.5x apart.
Context window
Gemini 3.5 Flash takes 1.05M tokens, Grok 4.5 500K.

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 FlashBarsGrok 4.5Ties
Coding6111 tie
Intelligence11
Agentic work311
Reasoning1031 tie
Math411 tie
Knowledge102
Web design161 tie
General265
All shared boards61404 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index611
Coding benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
LiveBench codingNot measured94.3%Only Grok 4.5 measured
LMArena WebDev14991553Grok 4.5
AA Coding IndexNot measured72.4Only Grok 4.5 measured
LiveCodeBench (Vals AI)87.6%87.3%Gemini 3.5 Flash
SWE-bench Verified (Vals AI)78.8%86.6%Grok 4.5
Terminal-Bench 4 (Vals AI)6.1%8.6%Grok 4.5
Vibe Code Bench (Vals AI)48.7%69.0%Grok 4.5
Code migration (Vals AI)26.8%36.6%Grok 4.5
ProgramBench (Vals AI)0.0%0.0%Tie
IOI (Vals AI)Not measured40.6%Only Grok 4.5 measured
Terminal-Bench 2.1 (Vals AI)74.2%67.8%Gemini 3.5 Flash
SkillsBench (Vals AI)52.7%66.0%Grok 4.5
CyberBench (Vals AI)Not measured71.0%Only Grok 4.5 measured
SciCode53.9%55.0%Grok 4.5
Terminal-Bench Hard (Artificial Analysis run)46.2%Not measuredOnly Gemini 3.5 Flash measured
FrontierCodeNot measured42.4%Only Grok 4.5 measured
WeirdML62.6%46.4%Gemini 3.5 Flash
ALE-Bench911.01309.3Grok 4.5
LMArena Text: coding14931474Gemini 3.5 Flash
LMArena Text: software and IT14941471Gemini 3.5 Flash
LMArena WebDev: React14951556Grok 4.5
LMArena WebDev: HTML15221567Grok 4.5
LMArena WebDev: from an image15041562Grok 4.5
SciCode12.3%6.5%Gemini 3.5 Flash
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11
Intelligence benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
AA Intelligence Index33.638.8Grok 4.5
Epoch Capabilities Index154.9154.1Gemini 3.5 Flash
Agentic workLike-for-likePublic boards, shown as published, kept out of the index311
Agentic work benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
AA Agentic IndexNot measured41.2Only Grok 4.5 measured
Design Arena: agents building web apps12021218Grok 4.5
Design Arena: agents building full-stack apps11971249Grok 4.5
Design Arena: agents building mobile apps11741221Grok 4.5
Design Arena: agents building Android apps11841242Grok 4.5
Design Arena: agents building Godot games10981229Grok 4.5
Design Arena: agents building games11801236Grok 4.5
Design Arena: HTML slides11421204Grok 4.5
Design Arena: PowerPoint slides11791233Grok 4.5
LiveBench researchNot measured85.9%Only Grok 4.5 measured
LiveBench browserNot measured44.0%Only Grok 4.5 measured
LiveBench long agenticNot measured27.9%Only Grok 4.5 measured
SREBench (Vals AI)Not measured0.8%Only Grok 4.5 measured
Finance Agent (Vals AI)57.9%48.4%Gemini 3.5 Flash
Tax Agent Bench (Vals AI)21.6%24.9%Grok 4.5
Legal Research Bench (Vals AI)30.8%38.0%Grok 4.5
Excel Modeling Benchmark (Vals AI)63.5%52.9%Gemini 3.5 Flash
Terminal-Bench-Science (Vals AI)5.7%Not measuredOnly Gemini 3.5 Flash measured
Time Horizon Index (Vals AI)Not measured6.3%Only Grok 4.5 measured
τ²-Bench Telecom95.6%Not measuredOnly Gemini 3.5 Flash measured
APEX-Agents27.5%56.2%Grok 4.5
PostTrainBenchNot measured23.4%Only Grok 4.5 measured
Vending-Bench 2$5,396$3,887Gemini 3.5 Flash
LMArena SearchNot measured1216Only Grok 4.5 measured
Neither model has a result on the other 17 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index103
Reasoning benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
GPQA Diamond92.7%92.9%Grok 4.5
LiveBench reasoningNot measured87.2%Only Grok 4.5 measured
MMMU Pro (Vals AI)88.3%61.8%Gemini 3.5 Flash
GPQA Diamond (Artificial Analysis run)92.2%93.1%Grok 4.5
Humanity's Last Exam (Artificial Analysis run)42.7%42.7%Tie
GPQA Diamond (Epoch AI run)92.8%93.4%Grok 4.5
ARC-AGI92.5%87.2%Gemini 3.5 Flash
ARC-AGI-272.1%52.6%Gemini 3.5 Flash
SimpleBench76.7%70.0%Gemini 3.5 Flash
Chess puzzles45.0%35.0%Gemini 3.5 Flash
Mystery game puzzles32.0%Not measuredOnly Gemini 3.5 Flash measured
EBR-bench4.8%Not measuredOnly Gemini 3.5 Flash measured
LMArena Text: hard prompts14881462Gemini 3.5 Flash
LMArena Text: expert14951465Gemini 3.5 Flash
LMArena Text: hard prompts in English14831464Gemini 3.5 Flash
LMArena Vision: diagrams13231304Gemini 3.5 Flash
LMArena Vision: homework13301295Gemini 3.5 Flash
Kagi LLM BenchmarkNot measured83.5%Only Grok 4.5 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index41
Math benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
OTIS Mock AIME95.6%97.8%Grok 4.5
FrontierMath, tiers 1 to 362.8%57.2%Gemini 3.5 Flash
FrontierMath, tier 426.8%24.4%Gemini 3.5 Flash
ProofBench31.0%31.0%Tie
LMArena Text: math15041460Gemini 3.5 Flash
LMArena Text: mathematical work14951482Gemini 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 index102
Knowledge benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
MMLU Pro89.5%89.2%Gemini 3.5 Flash
LegalBench (Vals AI)83.6%86.0%Grok 4.5
CorpFin (Vals AI)64.7%67.4%Grok 4.5
TaxEval (Vals AI)74.4%71.7%Gemini 3.5 Flash
MortgageTax (Vals AI)68.1%61.8%Gemini 3.5 Flash
MedCode (Vals AI)55.8%43.3%Gemini 3.5 Flash
SimpleQA Verified66.2%48.3%Gemini 3.5 Flash
LMArena Text: science14951464Gemini 3.5 Flash
LMArena Text: medicine and healthcare14831440Gemini 3.5 Flash
LMArena Text: legal and government14881463Gemini 3.5 Flash
LMArena Text: business and finance14671441Gemini 3.5 Flash
FACTS Benchmark Suite63.1%50.2%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 index16
Web design benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
Design Arena: websites12681281Grok 4.5
Design Arena: UI components12731279Grok 4.5
Design Arena: game dev12631263Tie
Design Arena: data viz12361266Grok 4.5
Design Arena: 3D12441257Grok 4.5
Design Arena: all code categories12661275Grok 4.5
Design Arena: SVG12541215Gemini 3.5 Flash
Design Arena: ASCII art12541257Grok 4.5
LiveBench designNot measured78.1%Only Grok 4.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index265
General benchmarks for Gemini 3.5 Flash and Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
LiveBench data analysisNot measured73.0%Only Grok 4.5 measured
Public Benefits Bench (Vals AI)59.5%Not measuredOnly Gemini 3.5 Flash measured
SAGE (Vals AI)49.9%35.0%Gemini 3.5 Flash
MedScribe (Vals AI)76.6%86.9%Grok 4.5
Vals Multimodal Index62.9%63.4%Grok 4.5
IFBench76.3%Not measuredOnly Gemini 3.5 Flash measured
Long context reasoning (AA-LCR)74.3%79.3%Grok 4.5
DTBench94.7%96.5%Grok 4.5
LMCA47.1%45.2%Gemini 3.5 Flash
Surface Evolver Bench58.1%74.4%Grok 4.5
Furniture assemblyNot measured22.5%Only Grok 4.5 measured
LMArena Text14821448Gemini 3.5 Flash
LMArena Text: instruction following14671445Gemini 3.5 Flash
LMArena Text: creative writing14701442Gemini 3.5 Flash
LMArena Vision13081287Gemini 3.5 Flash
LMArena Text: English14811453Gemini 3.5 Flash
LMArena Text: non-English14751440Gemini 3.5 Flash
LMArena Text: Chinese15271495Gemini 3.5 Flash
LMArena Text: German14941448Gemini 3.5 Flash
LMArena Text: Japanese14861430Gemini 3.5 Flash
LMArena Text: Korean14481406Gemini 3.5 Flash
LMArena Text: French14901457Gemini 3.5 Flash
LMArena Text: Spanish14801451Gemini 3.5 Flash
LMArena Text: Russian14931449Gemini 3.5 Flash
LMArena Text: Polish15161432Gemini 3.5 Flash
LMArena Text: multi-turn14811456Gemini 3.5 Flash
LMArena Text: longer queries14831462Gemini 3.5 Flash
LMArena Text: writing and language14781445Gemini 3.5 Flash
LMArena Text: entertainment and media14591434Gemini 3.5 Flash
LMArena Vision: English13051285Gemini 3.5 Flash
LMArena Vision: Chinese13771345Gemini 3.5 Flash
LMArena Vision: reading text13171293Gemini 3.5 Flash
LMArena Vision: humor13211276Gemini 3.5 Flash
LMArena Vision: creative writing13011293Gemini 3.5 Flash
LMArena Document14631452Gemini 3.5 Flash
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 Grok 4.5
BenchmarkGemini 3.5 FlashGrok 4.5Leader
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
Grok 4.5$0.0050Fits in one request

Grok 4.5 costs less

Repository review

50K input + 3K output tokens

Gemini 3.5 Flash$0.102Fits in one request
Grok 4.5$0.118Fits 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
Grok 4.5$0.460Fits 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 Grok 4.5
SpecificationGoogle Gemini 3.5 FlashSpaceXAI Grok 4.5
MakerGooglexAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 19, 2026July 8, 2026
Context window1.05M500K
Input $/Mtok$1.50$2.00
Output $/Mtok$9.00$6.00
Coding index39.858.6
Independent measurements behind it46
Cost per solved task$1.21$0.62
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash better than Grok 4.5 for coding?

Pick Grok 4.5 for coding: it scores 58.6 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash. Pick Gemini 3.5 Flash for a larger context window (1.05M against 500K tokens) and work measured by LiveCodeBench (Vals AI) or Terminal-Bench 2.1 (Vals AI), where it leads.

Which is cheaper, Gemini 3.5 Flash or Grok 4.5?

Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; Grok 4.5 costs $2.00 and $6.00. Per solved SWE-bench Verified task, Gemini 3.5 Flash costs $1.21 and Grok 4.5 $0.62.

Which has the bigger context window, Gemini 3.5 Flash or Grok 4.5?

Gemini 3.5 Flash, with 1.05M tokens against 500K.

How many benchmarks is the Gemini 3.5 Flash vs Grok 4.5 comparison based on?

105 benchmarks have a result for both models as of October 21, 2026. Gemini 3.5 Flash's coding index rests on 4 independent benchmarks and Grok 4.5's on 6. Where only one model has a result, the page says so instead of naming a winner.

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