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Gemini 3.5 Flash vs o3

Gemini 3.5 Flash leads o3 on the Artificial Analysis Intelligence Index, 33.6 to 20.2, at about the same output price ($9.00 vs $8.00 per million). Updated October 22, 2026; 75 benchmarks have a result for both.

Replace Gemini 3.5 Flash Replace o3
Gemini 3.5 FlashGoogle
Coding
39.8
Overall
63.8
Output $/M
$9.00
70
o3OpenAI
Coding
No data
Overall
51.1
Output $/M
$8.00
5
vs boards won of 75 shared

Gemini 3.5 Flash or o3: which to pick

Only Gemini 3.5 Flash has a coding score, 39.8 on the Vibe Coding Index; o3 has none, so the two cannot be ranked on coding.

Pick o3 for output tokens 1.1x cheaper ($8.00 vs $9.00 per million) and a lower cost per solved task ($0.571 against $1.21).

Model AGemini 3.5 FlashGoogle39.8/1004 independent benchmarks$1.21 per solved taskModel Bo3OpenAINot benchmarkedNo coding benchmark$0.571 per solved task
Shared results
75
Gemini 3.5 Flash only
37
o3 only
27
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, o3 not benchmarked.
Widest category
Web design, 24.9 points apart on average over 5 shared benchmarks.
Widest single gap
ARC-AGI-2: Gemini 3.5 Flash 72.1% against o3 6.5%, 65.5 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash $9.00 against o3 $8.00 per million output tokens, 1.1x apart.
Context window
Gemini 3.5 Flash takes 1.05M tokens, o3 200K.

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 FlashBarso3Ties
Coding61
Intelligence20
Agentic work10
Reasoning150
Math40
Knowledge102
Web design50
General272
All shared boards705
CodingLike-for-likeSix of these boards feed the Vibe Coding Index61
Coding benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
Aider polyglotNot measured81.3%Only o3 measured
SWE-bench VerifiedNot measured58.4%Only o3 measured
SWE-bench MultimodalNot measured36.0%Only o3 measured
LMArena WebDev1499Not measuredOnly Gemini 3.5 Flash measured
LiveCodeBench (Vals AI)87.6%83.9%Gemini 3.5 Flash
SWE-bench Verified (Vals AI)78.8%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench 4 (Vals AI)6.1%Not measuredOnly Gemini 3.5 Flash measured
Vibe Code Bench (Vals AI)48.7%Not measuredOnly Gemini 3.5 Flash measured
Code migration (Vals AI)26.8%Not measuredOnly Gemini 3.5 Flash measured
ProgramBench (Vals AI)0.0%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench 2.1 (Vals AI)74.2%Not measuredOnly Gemini 3.5 Flash measured
SkillsBench (Vals AI)52.7%Not measuredOnly Gemini 3.5 Flash measured
LiveCodeBench (Artificial Analysis run)Not measured80.8%Only o3 measured
SciCode53.9%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench Hard (Artificial Analysis run)46.2%37.1%Gemini 3.5 Flash
GSO-BenchNot measured8.8%Only o3 measured
WeirdML62.6%52.4%Gemini 3.5 Flash
ALE-Bench911.0933.5o3
LMArena Text: coding14931407Gemini 3.5 Flash
LMArena Text: software and IT14941415Gemini 3.5 Flash
LMArena WebDev: React1495Not measuredOnly Gemini 3.5 Flash measured
LMArena WebDev: HTML1522Not measuredOnly Gemini 3.5 Flash measured
LMArena WebDev: from an image1504Not measuredOnly Gemini 3.5 Flash measured
SciCode12.3%9.2%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 index20
Intelligence benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
AA Intelligence Index33.620.2Gemini 3.5 Flash
Epoch Capabilities Index154.9146.7Gemini 3.5 Flash
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
Agentic work benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
Design Arena: agents building web apps1202Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building full-stack apps1197Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building mobile apps1174Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building Android apps1185Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building Godot games1098Not measuredOnly Gemini 3.5 Flash measured
Design Arena: agents building games1180Not measuredOnly Gemini 3.5 Flash measured
Design Arena: HTML slides1093Not measuredOnly Gemini 3.5 Flash measured
Design Arena: PowerPoint slides1154Not measuredOnly Gemini 3.5 Flash measured
Finance Agent (Vals AI)57.9%Not measuredOnly Gemini 3.5 Flash measured
Tax Agent Bench (Vals AI)21.6%Not measuredOnly Gemini 3.5 Flash measured
Legal Research Bench (Vals AI)30.8%Not measuredOnly Gemini 3.5 Flash measured
Excel Modeling Benchmark (Vals AI)63.5%Not measuredOnly Gemini 3.5 Flash measured
Terminal-Bench-Science (Vals AI)5.7%Not measuredOnly Gemini 3.5 Flash measured
τ²-Bench Telecom95.6%80.7%Gemini 3.5 Flash
APEX-Agents27.5%Not measuredOnly Gemini 3.5 Flash measured
METR time horizonsNot measured65.4%Only o3 measured
GDPvalNot measured30.8%Only o3 measured
DeepResearch BenchNot measured45.2%Only o3 measured
OSWorldNot measured23.0%Only o3 measured
Vending-Bench 2$5,396Not measuredOnly Gemini 3.5 Flash measured
Berkeley Function Calling Leaderboard (BFCL)Not measured63.0%Only o3 measured
BrowseComp-PlusNot measured65.9%Only o3 measured
Neither model has a result on the other 19 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index150
Reasoning benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
GPQA Diamond92.7%84.1%Gemini 3.5 Flash
MMMU Pro (Vals AI)88.3%80.4%Gemini 3.5 Flash
GPQA Diamond (Artificial Analysis run)92.2%82.7%Gemini 3.5 Flash
Humanity's Last Exam (Artificial Analysis run)42.7%20.1%Gemini 3.5 Flash
GPQA Diamond (Epoch AI run)92.8%81.8%Gemini 3.5 Flash
ARC-AGI92.5%60.8%Gemini 3.5 Flash
ARC-AGI-272.1%6.5%Gemini 3.5 Flash
SimpleBench76.7%53.1%Gemini 3.5 Flash
Chess puzzles45.0%37.0%Gemini 3.5 Flash
Mystery game puzzles32.0%29.0%Gemini 3.5 Flash
EBR-bench4.8%Not measuredOnly Gemini 3.5 Flash measured
VPCTNot measured52.0%Only o3 measured
LMArena Text: hard prompts14881402Gemini 3.5 Flash
LMArena Text: expert14951402Gemini 3.5 Flash
LMArena Text: hard prompts in English14831411Gemini 3.5 Flash
LMArena Vision: diagrams13231220Gemini 3.5 Flash
LMArena Vision: homework13301234Gemini 3.5 Flash
Kagi LLM BenchmarkNot measured67.6%Only o3 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index40
Math benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
AIMENot measured85.3%Only o3 measured
MATH 500 (Vals AI)Not measured94.6%Only o3 measured
MGSM (Vals AI)Not measured91.8%Only o3 measured
AA Math IndexNot measured88.3Only o3 measured
AIME 2025 (Artificial Analysis run)Not measured88.3%Only o3 measured
OTIS Mock AIME95.6%84.4%Gemini 3.5 Flash
FrontierMath, tiers 1 to 362.8%33.3%Gemini 3.5 Flash
FrontierMath, tier 426.8%Not measuredOnly Gemini 3.5 Flash measured
ProofBench31.0%Not measuredOnly Gemini 3.5 Flash measured
MATH level 5Not measured97.8%Only o3 measured
LMArena Text: math15041426Gemini 3.5 Flash
LMArena Text: mathematical work14951423Gemini 3.5 Flash
Neither model has a result on the other 1 board here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index102
Knowledge benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
MMLU Pro89.5%85.6%Gemini 3.5 Flash
LegalBench (Vals AI)83.6%83.8%o3
CorpFin (Vals AI)64.7%59.7%Gemini 3.5 Flash
TaxEval (Vals AI)74.4%74.6%o3
MortgageTax (Vals AI)68.1%65.7%Gemini 3.5 Flash
MedQA (Vals AI)Not measured96.1%Only o3 measured
MedCode (Vals AI)55.8%47.3%Gemini 3.5 Flash
MMLU Pro (Artificial Analysis run)Not measured85.3%Only o3 measured
SimpleQA Verified66.2%49.4%Gemini 3.5 Flash
GeoBenchNot measured74.0%Only o3 measured
LMArena Text: science14951429Gemini 3.5 Flash
LMArena Text: medicine and healthcare14831448Gemini 3.5 Flash
LMArena Text: legal and government14881428Gemini 3.5 Flash
LMArena Text: business and finance14671393Gemini 3.5 Flash
FACTS Benchmark Suite63.1%44.4%Gemini 3.5 Flash
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index50
Web design benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
Design Arena: websites12671036Gemini 3.5 Flash
Design Arena: UI components12691017Gemini 3.5 Flash
Design Arena: game dev12631034Gemini 3.5 Flash
Design Arena: data viz12361200Gemini 3.5 Flash
Design Arena: 3D1243Not measuredOnly Gemini 3.5 Flash measured
Design Arena: all code categories12661020Gemini 3.5 Flash
Design Arena: SVG1253Not measuredOnly Gemini 3.5 Flash measured
Design Arena: ASCII art1254Not measuredOnly Gemini 3.5 Flash measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index272
General benchmarks for Gemini 3.5 Flash and o3
BenchmarkGemini 3.5 Flasho3Leader
Public Benefits Bench (Vals AI)59.5%Not measuredOnly Gemini 3.5 Flash measured
SAGE (Vals AI)49.9%41.8%Gemini 3.5 Flash
MedScribe (Vals AI)76.6%76.7%o3
Vals Multimodal Index62.9%Not measuredOnly Gemini 3.5 Flash measured
IFBench76.3%71.4%Gemini 3.5 Flash
Long context reasoning (AA-LCR)74.3%74.7%o3
DTBench94.7%84.8%Gemini 3.5 Flash
LMCA47.1%39.7%Gemini 3.5 Flash
Fiction.LiveBenchNot measured88.9%Only o3 measured
Creative writing (Lech Mazur)Not measured83.9%Only o3 measured
CL-benchNot measured17.8%Only o3 measured
Surface Evolver Bench58.1%Not measuredOnly Gemini 3.5 Flash measured
LMArena Text14821410Gemini 3.5 Flash
LMArena Text: instruction following14671368Gemini 3.5 Flash
LMArena Text: creative writing14701359Gemini 3.5 Flash
LMArena Vision13081214Gemini 3.5 Flash
LMArena Text: English14811417Gemini 3.5 Flash
LMArena Text: non-English14751401Gemini 3.5 Flash
LMArena Text: Chinese15271437Gemini 3.5 Flash
LMArena Text: German14941420Gemini 3.5 Flash
LMArena Text: Japanese14861403Gemini 3.5 Flash
LMArena Text: Korean14481370Gemini 3.5 Flash
LMArena Text: French14901430Gemini 3.5 Flash
LMArena Text: Spanish14801395Gemini 3.5 Flash
LMArena Text: Russian14931406Gemini 3.5 Flash
LMArena Text: Polish15161438Gemini 3.5 Flash
LMArena Text: multi-turn14811405Gemini 3.5 Flash
LMArena Text: longer queries14831372Gemini 3.5 Flash
LMArena Text: writing and language14781372Gemini 3.5 Flash
LMArena Text: entertainment and media14591373Gemini 3.5 Flash
LMArena Vision: English13051221Gemini 3.5 Flash
LMArena Vision: Chinese13771237Gemini 3.5 Flash
LMArena Vision: reading text13171218Gemini 3.5 Flash
LMArena Vision: humor13211222Gemini 3.5 Flash
LMArena Vision: captioningNot measured1210Only o3 measured
LMArena Vision: recognizing thingsNot measured1234Only o3 measured
LMArena Vision: creative writing13011201Gemini 3.5 Flash
LMArena Document1463Not measuredOnly Gemini 3.5 Flash measured
Neither model has a result on the other 8 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 o3
BenchmarkGemini 3.5 Flasho3Leader
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
o3$0.0060Fits in one request

Same cost

Repository review

50K input + 3K output tokens

Gemini 3.5 Flash$0.102Fits in one request
o3$0.124Fits 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
o3$0.480Exceeds the context window

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 o3
SpecificationGoogle Gemini 3.5 FlashOpenAI o3
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 19, 2026April 16, 2025
Context window1.05M200K
Input $/Mtok$1.50$2.00
Output $/Mtok$9.00$8.00
Coding index39.8Not benchmarked
Independent measurements behind it40
Cost per solved task$1.21$0.571
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash better than o3 for coding?

Only Gemini 3.5 Flash has a coding score, 39.8 on the Vibe Coding Index; o3 has none, so the two cannot be ranked on coding. Pick o3 for output tokens 1.1x cheaper ($8.00 vs $9.00 per million) and a lower cost per solved task ($0.571 against $1.21).

Which is cheaper, Gemini 3.5 Flash or o3?

Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; o3 costs $2.00 and $8.00. Per solved SWE-bench Verified task, Gemini 3.5 Flash costs $1.21 and o3 $0.571.

Which has the bigger context window, Gemini 3.5 Flash or o3?

Gemini 3.5 Flash, with 1.05M tokens against 200K.

How many benchmarks is the Gemini 3.5 Flash vs o3 comparison based on?

75 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 o3's on 0. Where only one model has a result, the page says so instead of naming a winner.

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