Gemini 3.8 Flash vs o4 Mini

Updated October 21, 2026. 69 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Gemini 3.8 Flash Replace o4 Mini

Gemini 3.8 FlashGoogle

Coding: 70.5
Overall: 40.9
Output $/M: $4.125

o4 MiniOpenAI

Coding: 68.6
Overall: 16.7
Output $/M: $4.40

vs boards won of 69 shared

Decision reading

Gemini 3.8 Flash and o4 Mini are level for coding, 70.5 against 68.6 on the Vibe Coding Index, so price and context decide.

Pick o4 Mini when what matters is TaxEval (Vals AI) or SAGE (Vals AI), where it leads. Pick Gemini 3.8 Flash when output tokens cost 1.1x less, or when the context window is larger, 1.05M against 200K tokens.

Model AGemini 3.8 FlashGoogle70.5/1002 independent benchmarks$2.74 per solved task Model Bo4 MiniOpenAI68.6/1002 independent benchmarksNo cost per solved task

695725

Shared results: 69
Gemini 3.8 Flash only: 57
o4 Mini only: 25
Like-for-like categories: 7 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.

Coding
Vibe Coding Index, four public coding benchmarks
No call
Level: 70.5 against 68.6, inside 2 points.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 40.9 against 16.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Gemini 3.8 Flash has a AA Agentic Index result, 40.2.
Directional only
Reasoning
GPQA Diamond
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 94.4% against 74.5%.
Same board, both measured
Math
AIME
No call
Only o4 Mini has a AIME result, 83.7%.
Directional only
Knowledge
MMLU Pro
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 90.2% against 80.6%.
Same board, both measured
Web design
Design Arena: websites
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 1301 against 985.
Same board, both measured
General
Vals Index
No call
Only Gemini 3.8 Flash has a Vals Index result, 56.0%.
Directional only
Long documents
Listed context window
Gemini 3.8 Flash
Gemini 3.8 Flash takes 1.05M tokens against 200K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3.8 Flash
Gemini 3.8 Flash $0.0029, o4 Mini $0.0033 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 3.8 Flash has the number, $2.74.
Directional only

At a glance

Coding index: Gemini 3.8 Flash 70.5 from 2 benchmarks, o4 Mini 68.6 from 2 benchmarks.
Widest category: Web design, 41.6 points apart on average over 6 shared benchmarks.
Widest single gap: ARC-AGI-2: Gemini 3.8 Flash 89.2% against o4 Mini 6.1%, 83.1 points apart on a 0 to 100 scale.
Output price: Gemini 3.8 Flash $4.125 against o4 Mini $4.40 per million output tokens, 1.1x apart.
Context window: Gemini 3.8 Flash takes 1.05M tokens, o4 Mini 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
Category	Gemini 3.8 Flash	o4 Mini
Coding	4	0
Intelligence	2	0
Reasoning	14	0
Math	5	0
Knowledge	9	1
Web design	6	0
General	27	1
All shared boards	67	2

CodingLike-for-likeFour of these boards feed the Vibe Coding Index40

Coding benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
Aider polyglot	Not measured	72.0%	Only o4 Mini measured
SWE-bench Verified	Not measured	64.6%	Only o4 Mini measured
SWE-bench Multimodal	Not measured	33.9%	Only o4 Mini measured
LiveBench coding	82.2%	Not measured	Only Gemini 3.8 Flash measured
LMArena WebDev	1585	Not measured	Only Gemini 3.8 Flash measured
AA Coding Index	76.3	Not measured	Only Gemini 3.8 Flash measured
LiveCodeBench (Vals AI)	89.5%	82.2%	Gemini 3.8 Flash
SWE-bench Verified (Vals AI)	80.0%	Not measured	Only Gemini 3.8 Flash measured
Terminal-Bench 4 (Vals AI)	19.7%	Not measured	Only Gemini 3.8 Flash measured
Vibe Code Bench (Vals AI)	78.7%	Not measured	Only Gemini 3.8 Flash measured
Code migration (Vals AI)	36.5%	Not measured	Only Gemini 3.8 Flash measured
ProgramBench (Vals AI)	1.0%	Not measured	Only Gemini 3.8 Flash measured
IOI (Vals AI)	56.9%	Not measured	Only Gemini 3.8 Flash measured
Terminal-Bench 2.1 (Vals AI)	81.3%	Not measured	Only Gemini 3.8 Flash measured
SWE-bench Multimodal (Vals AI)	40.8%	Not measured	Only Gemini 3.8 Flash measured
Vibe Code Bench 1-100 (Vals AI)	18.8%	Not measured	Only Gemini 3.8 Flash measured
SkillsBench (Vals AI)	58.0%	Not measured	Only Gemini 3.8 Flash measured
CyberBench (Vals AI)	43.8%	Not measured	Only Gemini 3.8 Flash measured
LiveCodeBench (Artificial Analysis run)	Not measured	85.9%	Only o4 Mini measured
SciCode	56.6%	Not measured	Only Gemini 3.8 Flash measured
Terminal-Bench Hard (Artificial Analysis run)	Not measured	15.2%	Only o4 Mini measured
FrontierCode	41.2%	Not measured	Only Gemini 3.8 Flash measured
FrontierSWE	19.6%	Not measured	Only Gemini 3.8 Flash measured
GSO-Bench	Not measured	3.6%	Only o4 Mini measured
WeirdML	84.8%	52.6%	Gemini 3.8 Flash
ALE-Bench	1269.7	Not measured	Only Gemini 3.8 Flash measured
LMArena Text: coding	1508	1368	Gemini 3.8 Flash
LMArena Text: software and IT	1507	1367	Gemini 3.8 Flash
LMArena WebDev: React	1577	Not measured	Only Gemini 3.8 Flash measured
LMArena WebDev: HTML	1616	Not measured	Only Gemini 3.8 Flash measured
LMArena WebDev: from an image	1593	Not measured	Only Gemini 3.8 Flash measured
Neither model has a result on the other 7 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20

Intelligence benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
AA Intelligence Index	40.9	16.7	Gemini 3.8 Flash
Epoch Capabilities Index	157.4	145.5	Gemini 3.8 Flash

Agentic workDirectional onlyPublic boards, shown as published, kept out of the index27 boards, none shared

Agentic work benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
AA Agentic Index	40.2	Not measured	Only Gemini 3.8 Flash measured
Design Arena: agents building web apps	1238	Not measured	Only Gemini 3.8 Flash measured
Design Arena: agents building full-stack apps	1244	Not measured	Only Gemini 3.8 Flash measured
Design Arena: agents building mobile apps	1236	Not measured	Only Gemini 3.8 Flash measured
Design Arena: agents building Android apps	1078	Not measured	Only Gemini 3.8 Flash measured
Design Arena: agents building Godot games	1273	Not measured	Only Gemini 3.8 Flash measured
Design Arena: PowerPoint slides	1178	Not measured	Only Gemini 3.8 Flash measured
Design Arena: spreadsheets	1052	Not measured	Only Gemini 3.8 Flash measured
LiveBench research	79.1%	Not measured	Only Gemini 3.8 Flash measured
LiveBench browser	64.0%	Not measured	Only Gemini 3.8 Flash measured
LiveBench long agentic	30.1%	Not measured	Only Gemini 3.8 Flash measured
SREBench (Vals AI)	11.1%	Not measured	Only Gemini 3.8 Flash measured
Finance Agent (Vals AI)	61.4%	Not measured	Only Gemini 3.8 Flash measured
Tax Agent Bench (Vals AI)	32.1%	Not measured	Only Gemini 3.8 Flash measured
Legal Research Bench (Vals AI)	38.9%	Not measured	Only Gemini 3.8 Flash measured
Harvey's Legal Agent Benchmark (Vals AI)	12.1%	Not measured	Only Gemini 3.8 Flash measured
Excel Modeling Benchmark (Vals AI)	72.2%	Not measured	Only Gemini 3.8 Flash measured
BioMysteryBench (Vals AI)	62.2%	Not measured	Only Gemini 3.8 Flash measured
Terminal-Bench-Science (Vals AI)	8.6%	Not measured	Only Gemini 3.8 Flash measured
Vals Science Index	35.8%	Not measured	Only Gemini 3.8 Flash measured
Time Horizon Index (Vals AI)	18.8%	Not measured	Only Gemini 3.8 Flash measured
CUA-bench (Vals AI)	4.2%	Not measured	Only Gemini 3.8 Flash measured
τ²-Bench Telecom	Not measured	55.6%	Only o4 Mini measured
APEX-Agents	64.3%	Not measured	Only Gemini 3.8 Flash measured
METR time horizons	Not measured	63.9%	Only o4 Mini measured
Remote Labor Index	5.8%	Not measured	Only Gemini 3.8 Flash measured
Vending-Bench 2	$5,094	Not measured	Only Gemini 3.8 Flash measured
Neither model has a result on the other 12 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index140

Reasoning benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
GPQA Diamond	94.4%	74.5%	Gemini 3.8 Flash
LiveBench reasoning	89.3%	Not measured	Only Gemini 3.8 Flash measured
MysteryMechanism (Vals AI)	36.5%	Not measured	Only Gemini 3.8 Flash measured
MMMU Pro (Vals AI)	89.1%	79.7%	Gemini 3.8 Flash
GPQA Diamond (Artificial Analysis run)	95.3%	78.4%	Gemini 3.8 Flash
Humanity's Last Exam (Artificial Analysis run)	47.8%	16.5%	Gemini 3.8 Flash
GPQA Diamond (Epoch AI run)	95.4%	79.6%	Gemini 3.8 Flash
ARC-AGI	98.5%	58.7%	Gemini 3.8 Flash
ARC-AGI-2	89.2%	6.1%	Gemini 3.8 Flash
SimpleBench	Not measured	38.7%	Only o4 Mini measured
Chess puzzles	58.0%	22.0%	Gemini 3.8 Flash
Mystery game puzzles	47.0%	5.0%	Gemini 3.8 Flash
VPCT	Not measured	57.5%	Only o4 Mini measured
LMArena Text: hard prompts	1509	1351	Gemini 3.8 Flash
LMArena Text: expert	1526	1343	Gemini 3.8 Flash
LMArena Text: hard prompts in English	1504	1366	Gemini 3.8 Flash
LMArena Vision: diagrams	1345	1197	Gemini 3.8 Flash
LMArena Vision: homework	1351	1234	Gemini 3.8 Flash
Neither model has a result on the other 3 boards here

MathLike-for-likePublic boards, shown as published, kept out of the index50

Math benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
AIME	Not measured	83.7%	Only o4 Mini measured
MATH 500 (Vals AI)	Not measured	94.2%	Only o4 Mini measured
MGSM (Vals AI)	Not measured	93.4%	Only o4 Mini measured
AA Math Index	Not measured	90.7	Only o4 Mini measured
AIME 2025 (Artificial Analysis run)	Not measured	90.7%	Only o4 Mini measured
OTIS Mock AIME	98.9%	81.7%	Gemini 3.8 Flash
FrontierMath, tiers 1 to 3	68.4%	36.1%	Gemini 3.8 Flash
FrontierMath, tier 4	22.0%	4.9%	Gemini 3.8 Flash
ProofBench	48.0%	Not measured	Only Gemini 3.8 Flash measured
MATH level 5	Not measured	97.8%	Only o4 Mini measured
LMArena Text: math	1532	1389	Gemini 3.8 Flash
LMArena Text: mathematical work	1519	1379	Gemini 3.8 Flash
Neither model has a result on the other 1 board here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index91

Knowledge benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
MMLU Pro	90.2%	80.6%	Gemini 3.8 Flash
LegalBench (Vals AI)	87.0%	79.2%	Gemini 3.8 Flash
CorpFin (Vals AI)	Not measured	59.0%	Only o4 Mini measured
TaxEval (Vals AI)	74.5%	74.8%	o4 Mini
MortgageTax (Vals AI)	65.3%	64.8%	Gemini 3.8 Flash
MedQA (Vals AI)	Not measured	96.0%	Only o4 Mini measured
MedCode (Vals AI)	48.1%	33.8%	Gemini 3.8 Flash
MMLU Pro (Artificial Analysis run)	Not measured	83.2%	Only o4 Mini measured
SimpleQA Verified	69.7%	19.6%	Gemini 3.8 Flash
GeoBench	Not measured	64.0%	Only o4 Mini measured
LMArena Text: science	1523	1354	Gemini 3.8 Flash
LMArena Text: medicine and healthcare	1508	1361	Gemini 3.8 Flash
LMArena Text: legal and government	1497	1350	Gemini 3.8 Flash
LMArena Text: business and finance	1479	1325	Gemini 3.8 Flash
Neither model has a result on the other 3 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index60

Web design benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
Design Arena: websites	1301	985	Gemini 3.8 Flash
Design Arena: UI components	1318	983	Gemini 3.8 Flash
Design Arena: game dev	1305	1004	Gemini 3.8 Flash
Design Arena: data viz	1269	990	Gemini 3.8 Flash
Design Arena: 3D	1295	854	Gemini 3.8 Flash
Design Arena: all code categories	1304	977	Gemini 3.8 Flash
Design Arena: SVG	1295	Not measured	Only Gemini 3.8 Flash measured
Design Arena: ASCII art	1264	Not measured	Only Gemini 3.8 Flash measured
LiveBench design	72.7%	Not measured	Only Gemini 3.8 Flash measured

GeneralLike-for-likePublic boards, shown as published, kept out of the index271

General benchmarks for Gemini 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
Vals Index	56.0%	Not measured	Only Gemini 3.8 Flash measured
LiveBench data analysis	54.0%	Not measured	Only Gemini 3.8 Flash measured
Public Benefits Bench (Vals AI)	65.3%	Not measured	Only Gemini 3.8 Flash measured
SAGE (Vals AI)	35.1%	41.1%	o4 Mini
MedScribe (Vals AI)	84.5%	69.1%	Gemini 3.8 Flash
IFBench	Not measured	68.7%	Only o4 Mini measured
Long context reasoning (AA-LCR)	84.0%	61.0%	Gemini 3.8 Flash
DTBench	95.7%	77.6%	Gemini 3.8 Flash
LMCA	52.9%	26.5%	Gemini 3.8 Flash
Fiction.LiveBench	Not measured	77.8%	Only o4 Mini measured
Creative writing (Lech Mazur)	Not measured	75.0%	Only o4 Mini measured
Surface Evolver Bench	76.9%	Not measured	Only Gemini 3.8 Flash measured
Furniture assembly	31.7%	Not measured	Only Gemini 3.8 Flash measured
LMArena Text	1499	1353	Gemini 3.8 Flash
LMArena Text: instruction following	1492	1320	Gemini 3.8 Flash
LMArena Text: creative writing	1488	1294	Gemini 3.8 Flash
LMArena Vision	1315	1194	Gemini 3.8 Flash
LMArena Text: English	1498	1367	Gemini 3.8 Flash
LMArena Text: non-English	1491	1337	Gemini 3.8 Flash
LMArena Text: Chinese	1553	1354	Gemini 3.8 Flash
LMArena Text: German	1501	1336	Gemini 3.8 Flash
LMArena Text: Japanese	1507	1308	Gemini 3.8 Flash
LMArena Text: Korean	1464	1312	Gemini 3.8 Flash
LMArena Text: French	1496	1364	Gemini 3.8 Flash
LMArena Text: Spanish	1487	1346	Gemini 3.8 Flash
LMArena Text: Russian	1514	1334	Gemini 3.8 Flash
LMArena Text: Polish	1497	1358	Gemini 3.8 Flash
LMArena Text: multi-turn	1503	1350	Gemini 3.8 Flash
LMArena Text: longer queries	1507	1315	Gemini 3.8 Flash
LMArena Text: writing and language	1494	1316	Gemini 3.8 Flash
LMArena Text: entertainment and media	1480	1308	Gemini 3.8 Flash
LMArena Vision: English	1318	1200	Gemini 3.8 Flash
LMArena Vision: Chinese	1416	1218	Gemini 3.8 Flash
LMArena Vision: reading text	1333	1197	Gemini 3.8 Flash
LMArena Vision: humor	1321	1199	Gemini 3.8 Flash
LMArena Vision: captioning	Not measured	1204	Only o4 Mini measured
LMArena Vision: recognizing things	Not measured	1218	Only o4 Mini measured
LMArena Vision: creative writing	1299	1166	Gemini 3.8 Flash
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 3.8 Flash and o4 Mini
Benchmark	Gemini 3.8 Flash	o4 Mini	Leader
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 3.8 Flash$0.0029Fits in one request

o4 Mini$0.0033Fits in one request

Gemini 3.8 Flash costs less

Repository review

50K input + 3K output tokens

Gemini 3.8 Flash$0.054Fits in one request

o4 Mini$0.068Fits in one request

Gemini 3.8 Flash costs less

Agent loop

200K input + 10K output tokens

Gemini 3.8 Flash$0.206Fits in one request

o4 Mini$0.264Exceeds the context window

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 3.8 Flash and o4 Mini
Specification	Google Gemini 3.8 Flash	OpenAI o4 Mini
Maker	Google	OpenAI
Weights	No public weights listed	No public weights listed
Released	September 2, 2026	April 16, 2025
Context window	1.05M	200K
Input $/Mtok	$0.825	$1.10
Output $/Mtok	$4.125	$4.40
Coding index	70.5	68.6
Independent measurements behind it	2	2
Cost per solved task	$2.74	Not computable
Source	OpenRouter listing	OpenRouter listing

Questions

Is Gemini 3.8 Flash better than o4 Mini for coding?

Gemini 3.8 Flash and o4 Mini are level for coding, 70.5 against 68.6 on the Vibe Coding Index, so price and context decide. Pick o4 Mini when what matters is TaxEval (Vals AI) or SAGE (Vals AI), where it leads. Pick Gemini 3.8 Flash when output tokens cost 1.1x less, or when the context window is larger, 1.05M against 200K tokens.

Which is cheaper, Gemini 3.8 Flash or o4 Mini?

Gemini 3.8 Flash costs $0.825 per million input tokens and $4.125 per million output tokens; o4 Mini costs $1.10 and $4.40. Cost per solved task is known for Gemini 3.8 Flash only.

Which has the bigger context window, Gemini 3.8 Flash or o4 Mini?

Gemini 3.8 Flash, with 1.05M tokens against 200K.

How many benchmarks is the Gemini 3.8 Flash vs o4 Mini comparison based on?

69 benchmarks have a result for both models as of October 21, 2026. Gemini 3.8 Flash's coding index rests on 2 independent benchmarks and o4 Mini's on 2. Where only one model has a result, the page says so instead of naming a winner.

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Decision reading

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Math

Knowledge

Web design

General

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

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