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Gemini 3.5 Flash vs Gemini 3.8 Flash

Gemini 3.8 Flash leads Gemini 3.5 Flash on coding, 61.6 to 39.8 on the Vibe Coding Index, and Gemini 3.8 Flash costs 2.4x less per output token ($3.75 vs $9.00 per million). Updated October 21, 2026; 102 benchmarks have a result for both.

Replace Gemini 3.5 Flash Replace Gemini 3.8 Flash
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
10
Gemini 3.8 FlashGoogle
Coding
61.6
Overall
69.0
Output $/M
$3.75
91
vs boards won of 102 shared, 1 tied

Gemini 3.5 Flash or Gemini 3.8 Flash: which to pick

Pick Gemini 3.8 Flash for coding: it scores 61.6 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash.

Pick Gemini 3.5 Flash for a lower cost per solved task ($1.21 against $2.74) and work measured by Design Arena: agents building Android apps or Design Arena: PowerPoint slides, where it leads.

Model AGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved taskModel BGemini 3.8 FlashGoogle61.6/1006 independent benchmarks$2.74 per solved task
Shared results
102
Gemini 3.5 Flash only
10
Gemini 3.8 Flash only
26
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, Gemini 3.8 Flash 61.6 from 6 benchmarks.
Widest category
Agentic work, 9.7 points apart on average over 13 shared benchmarks.
Widest single gap
APEX-Agents: Gemini 3.5 Flash 27.5% against Gemini 3.8 Flash 64.3%, 36.8 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash $9.00 against Gemini 3.8 Flash $3.75 per million output tokens, 2.4x apart.
Context window
Both take 1.05M tokens.

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 FlashBarsGemini 3.8 FlashTies
Coding0171 tie
Intelligence02
Agentic work310
Reasoning014
Math15
Knowledge29
Web design08
General426
All shared boards10911 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index017
Coding benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
LiveBench codingNot measured82.2%Only Gemini 3.8 Flash measured
LMArena WebDev14991585Gemini 3.8 Flash
AA Coding IndexNot measured76.3Only Gemini 3.8 Flash measured
LiveCodeBench (Vals AI)87.6%89.5%Gemini 3.8 Flash
SWE-bench Verified (Vals AI)78.8%80.0%Gemini 3.8 Flash
Terminal-Bench 4 (Vals AI)6.1%19.7%Gemini 3.8 Flash
Vibe Code Bench (Vals AI)48.7%78.7%Gemini 3.8 Flash
Code migration (Vals AI)26.8%36.5%Gemini 3.8 Flash
ProgramBench (Vals AI)0.0%1.0%Gemini 3.8 Flash
IOI (Vals AI)Not measured56.9%Only Gemini 3.8 Flash measured
Terminal-Bench 2.1 (Vals AI)74.2%81.3%Gemini 3.8 Flash
SWE-bench Multimodal (Vals AI)Not measured40.8%Only Gemini 3.8 Flash measured
Vibe Code Bench 1-100 (Vals AI)Not measured18.8%Only Gemini 3.8 Flash measured
SkillsBench (Vals AI)52.7%58.0%Gemini 3.8 Flash
CyberBench (Vals AI)Not measured43.8%Only Gemini 3.8 Flash measured
SciCode53.9%56.6%Gemini 3.8 Flash
Terminal-Bench Hard (Artificial Analysis run)46.2%Not measuredOnly Gemini 3.5 Flash measured
FrontierCodeNot measured41.2%Only Gemini 3.8 Flash measured
FrontierSWENot measured19.6%Only Gemini 3.8 Flash measured
WeirdML62.6%84.8%Gemini 3.8 Flash
ALE-Bench911.01269.7Gemini 3.8 Flash
LMArena Text: coding14931508Gemini 3.8 Flash
LMArena Text: software and IT14941507Gemini 3.8 Flash
LMArena WebDev: React14951577Gemini 3.8 Flash
LMArena WebDev: HTML15221616Gemini 3.8 Flash
LMArena WebDev: from an image15041593Gemini 3.8 Flash
SciCode12.3%12.3%Tie
Neither model has a result on the other 12 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
AA Intelligence Index33.640.9Gemini 3.8 Flash
Epoch Capabilities Index154.9157.4Gemini 3.8 Flash
Agentic workLike-for-likePublic boards, shown as published, kept out of the index310
Agentic work benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
AA Agentic IndexNot measured40.2Only Gemini 3.8 Flash measured
Design Arena: agents building web apps12021238Gemini 3.8 Flash
Design Arena: agents building full-stack apps11971244Gemini 3.8 Flash
Design Arena: agents building mobile apps11741236Gemini 3.8 Flash
Design Arena: agents building Android apps11841074Gemini 3.5 Flash
Design Arena: agents building Godot games10981273Gemini 3.8 Flash
Design Arena: agents building games1180Not measuredOnly Gemini 3.5 Flash measured
Design Arena: HTML slides1142Not measuredOnly Gemini 3.5 Flash measured
Design Arena: PowerPoint slides11791177Gemini 3.5 Flash
Design Arena: spreadsheetsNot measured1056Only Gemini 3.8 Flash measured
LiveBench researchNot measured79.1%Only Gemini 3.8 Flash measured
LiveBench browserNot measured64.0%Only Gemini 3.8 Flash measured
LiveBench long agenticNot measured30.1%Only Gemini 3.8 Flash measured
SREBench (Vals AI)Not measured11.1%Only Gemini 3.8 Flash measured
Finance Agent (Vals AI)57.9%61.4%Gemini 3.8 Flash
Tax Agent Bench (Vals AI)21.6%32.1%Gemini 3.8 Flash
Legal Research Bench (Vals AI)30.8%38.9%Gemini 3.8 Flash
Harvey's Legal Agent Benchmark (Vals AI)Not measured12.1%Only Gemini 3.8 Flash measured
Excel Modeling Benchmark (Vals AI)63.5%72.2%Gemini 3.8 Flash
BioMysteryBench (Vals AI)Not measured62.2%Only Gemini 3.8 Flash measured
Terminal-Bench-Science (Vals AI)5.7%8.6%Gemini 3.8 Flash
Vals Science IndexNot measured35.8%Only Gemini 3.8 Flash measured
Time Horizon Index (Vals AI)Not measured18.8%Only Gemini 3.8 Flash measured
CUA-bench (Vals AI)Not measured4.2%Only Gemini 3.8 Flash measured
τ²-Bench Telecom95.6%Not measuredOnly Gemini 3.5 Flash measured
APEX-Agents27.5%64.3%Gemini 3.8 Flash
Remote Labor IndexNot measured5.8%Only Gemini 3.8 Flash measured
Vending-Bench 2$5,396$5,094Gemini 3.5 Flash
Neither model has a result on the other 13 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index014
Reasoning benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
GPQA Diamond92.7%94.4%Gemini 3.8 Flash
LiveBench reasoningNot measured89.3%Only Gemini 3.8 Flash measured
MysteryMechanism (Vals AI)Not measured36.5%Only Gemini 3.8 Flash measured
MMMU Pro (Vals AI)88.3%89.1%Gemini 3.8 Flash
GPQA Diamond (Artificial Analysis run)92.2%95.3%Gemini 3.8 Flash
Humanity's Last Exam (Artificial Analysis run)42.7%47.8%Gemini 3.8 Flash
GPQA Diamond (Epoch AI run)92.8%95.4%Gemini 3.8 Flash
ARC-AGI92.5%98.5%Gemini 3.8 Flash
ARC-AGI-272.1%89.2%Gemini 3.8 Flash
SimpleBench76.7%Not measuredOnly Gemini 3.5 Flash measured
Chess puzzles45.0%58.0%Gemini 3.8 Flash
Mystery game puzzles32.0%47.0%Gemini 3.8 Flash
EBR-bench4.8%Not measuredOnly Gemini 3.5 Flash measured
LMArena Text: hard prompts14881509Gemini 3.8 Flash
LMArena Text: expert14951526Gemini 3.8 Flash
LMArena Text: hard prompts in English14831504Gemini 3.8 Flash
LMArena Vision: diagrams13231345Gemini 3.8 Flash
LMArena Vision: homework13301351Gemini 3.8 Flash
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index15
Math benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
OTIS Mock AIME95.6%98.9%Gemini 3.8 Flash
FrontierMath, tiers 1 to 362.8%68.4%Gemini 3.8 Flash
FrontierMath, tier 426.8%22.0%Gemini 3.5 Flash
ProofBench31.0%48.0%Gemini 3.8 Flash
LMArena Text: math15041532Gemini 3.8 Flash
LMArena Text: mathematical work14951519Gemini 3.8 Flash
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index29
Knowledge benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
MMLU Pro89.5%90.2%Gemini 3.8 Flash
LegalBench (Vals AI)83.6%87.0%Gemini 3.8 Flash
CorpFin (Vals AI)64.7%Not measuredOnly Gemini 3.5 Flash measured
TaxEval (Vals AI)74.4%74.5%Gemini 3.8 Flash
MortgageTax (Vals AI)68.1%65.3%Gemini 3.5 Flash
MedCode (Vals AI)55.8%48.1%Gemini 3.5 Flash
SimpleQA Verified66.2%69.7%Gemini 3.8 Flash
LMArena Text: science14951523Gemini 3.8 Flash
LMArena Text: medicine and healthcare14831508Gemini 3.8 Flash
LMArena Text: legal and government14881497Gemini 3.8 Flash
LMArena Text: business and finance14671479Gemini 3.8 Flash
FACTS Benchmark Suite63.1%69.4%Gemini 3.8 Flash
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index08
Web design benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
Design Arena: websites12681300Gemini 3.8 Flash
Design Arena: UI components12731319Gemini 3.8 Flash
Design Arena: game dev12631305Gemini 3.8 Flash
Design Arena: data viz12361269Gemini 3.8 Flash
Design Arena: 3D12441295Gemini 3.8 Flash
Design Arena: all code categories12661304Gemini 3.8 Flash
Design Arena: SVG12541295Gemini 3.8 Flash
Design Arena: ASCII art12541265Gemini 3.8 Flash
LiveBench designNot measured72.7%Only Gemini 3.8 Flash measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index426
General benchmarks for Gemini 3.5 Flash and Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
Vals IndexNot measured56.0%Only Gemini 3.8 Flash measured
LiveBench data analysisNot measured54.0%Only Gemini 3.8 Flash measured
Public Benefits Bench (Vals AI)59.5%65.3%Gemini 3.8 Flash
SAGE (Vals AI)49.9%35.1%Gemini 3.5 Flash
MedScribe (Vals AI)76.6%84.5%Gemini 3.8 Flash
Vals Multimodal Index62.9%Not measuredOnly Gemini 3.5 Flash measured
IFBench76.3%Not measuredOnly Gemini 3.5 Flash measured
Long context reasoning (AA-LCR)74.3%84.0%Gemini 3.8 Flash
DTBench94.7%95.7%Gemini 3.8 Flash
LMCA47.1%52.9%Gemini 3.8 Flash
Surface Evolver Bench58.1%76.9%Gemini 3.8 Flash
Furniture assemblyNot measured31.7%Only Gemini 3.8 Flash measured
LMArena Text14821499Gemini 3.8 Flash
LMArena Text: instruction following14671492Gemini 3.8 Flash
LMArena Text: creative writing14701488Gemini 3.8 Flash
LMArena Vision13081315Gemini 3.8 Flash
LMArena Text: English14811498Gemini 3.8 Flash
LMArena Text: non-English14751491Gemini 3.8 Flash
LMArena Text: Chinese15271553Gemini 3.8 Flash
LMArena Text: German14941501Gemini 3.8 Flash
LMArena Text: Japanese14861507Gemini 3.8 Flash
LMArena Text: Korean14481464Gemini 3.8 Flash
LMArena Text: French14901496Gemini 3.8 Flash
LMArena Text: Spanish14801487Gemini 3.8 Flash
LMArena Text: Russian14931514Gemini 3.8 Flash
LMArena Text: Polish15161497Gemini 3.5 Flash
LMArena Text: multi-turn14811503Gemini 3.8 Flash
LMArena Text: longer queries14831507Gemini 3.8 Flash
LMArena Text: writing and language14781494Gemini 3.8 Flash
LMArena Text: entertainment and media14591480Gemini 3.8 Flash
LMArena Vision: English13051318Gemini 3.8 Flash
LMArena Vision: Chinese13771416Gemini 3.8 Flash
LMArena Vision: reading text13171333Gemini 3.8 Flash
LMArena Vision: humor13211321Gemini 3.5 Flash
LMArena Vision: creative writing13011299Gemini 3.5 Flash
LMArena Document1463Not measuredOnly Gemini 3.5 Flash measured
Neither model has a result on the other 10 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 Gemini 3.8 Flash
BenchmarkGemini 3.5 FlashGemini 3.8 FlashLeader
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
Gemini 3.8 Flash$0.0026Fits in one request

Gemini 3.8 Flash costs less

Repository review

50K input + 3K output tokens

Gemini 3.5 Flash$0.102Fits in one request
Gemini 3.8 Flash$0.049Fits in one request

Gemini 3.8 Flash costs less

Agent loop

200K input + 10K output tokens

Gemini 3.5 Flash$0.390Fits in one request
Gemini 3.8 Flash$0.188Fits in one request

Gemini 3.8 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 Gemini 3.8 Flash
SpecificationGoogle Gemini 3.5 FlashGoogle Gemini 3.8 Flash
MakerGoogleGoogle
WeightsNo public weights listedNo public weights listed
ReleasedMay 19, 2026September 2, 2026
Context window1.05M1.05M
Input $/Mtok$1.50$0.75
Output $/Mtok$9.00$3.75
Coding index39.861.6
Independent measurements behind it46
Cost per solved task$1.21$2.74
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash better than Gemini 3.8 Flash for coding?

Pick Gemini 3.8 Flash for coding: it scores 61.6 on the Vibe Coding Index against 39.8 for Gemini 3.5 Flash. Pick Gemini 3.5 Flash for a lower cost per solved task ($1.21 against $2.74) and work measured by Design Arena: agents building Android apps or Design Arena: PowerPoint slides, where it leads.

Which is cheaper, Gemini 3.5 Flash or Gemini 3.8 Flash?

Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; Gemini 3.8 Flash costs $0.75 and $3.75. Per solved SWE-bench Verified task, Gemini 3.5 Flash costs $1.21 and Gemini 3.8 Flash $2.74.

Which has the bigger context window, Gemini 3.5 Flash or Gemini 3.8 Flash?

Neither: both take 1.05M tokens.

How many benchmarks is the Gemini 3.5 Flash vs Gemini 3.8 Flash comparison based on?

102 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 Gemini 3.8 Flash's on 6. Where only one model has a result, the page says so instead of naming a winner.

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<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/gemini-3-5-flash-vs-gemini-3-8-flash">LLMBenchmark.ai, Gemini 3.5 Flash vs Gemini 3.8 Flash</a></p>