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Gemini 3.8 Flash vs GPT-6 Astra

GPT-6 Astra leads Gemini 3.8 Flash on coding, 85.1 to 61.6 on the Vibe Coding Index, and Gemini 3.8 Flash costs 13.3x less per output token ($3.75 vs $50.00 per million). Updated October 22, 2026; 115 benchmarks have a result for both.

Replace Gemini 3.8 Flash Replace GPT-6 Astra
Gemini 3.8 FlashGoogle
Coding
61.6
Overall
69.0
Output $/M
$3.75
42
GPT-6 AstraOpenAI
Coding
85.1
Overall
83.0
Output $/M
$50.00
71
vs boards won of 115 shared, 2 tied

Gemini 3.8 Flash or GPT-6 Astra: which to pick

Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 61.6 for Gemini 3.8 Flash, though on 5 benchmarks against 6.

Pick Gemini 3.8 Flash for output tokens 13.3x cheaper ($3.75 vs $50.00 per million) and work measured by CyberBench (Vals AI) or SciCode, where it leads.

Model AGemini 3.8 FlashGoogle61.6/1006 independent benchmarks$2.74 per solved taskModel BGPT-6 AstraOpenAI85.1/1005 independent benchmarksNo cost per solved task
Shared results
115
Gemini 3.8 Flash only
13
GPT-6 Astra only
6
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 3.8 Flash 61.6 from 6 benchmarks, GPT-6 Astra 85.1 from 5 benchmarks.
Widest category
Math, 28.3 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Gemini 3.8 Flash 22.0% against GPT-6 Astra 97.6%, 75.6 points apart on a 0 to 100 scale.
Output price
Gemini 3.8 Flash $3.75 against GPT-6 Astra $50.00 per million output tokens, 13.3x apart.
Context window
Gemini 3.8 Flash takes 1.05M tokens, GPT-6 Astra 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 3.8 FlashBarsGPT-6 AstraTies
Coding4181 tie
Intelligence02
Agentic work420
Reasoning581 tie
Math24
Knowledge43
Web design09
General237
All shared boards42712 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index418
Coding benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
LiveBench coding82.2%93.7%GPT-6 Astra
LMArena WebDev15851774GPT-6 Astra
AA Coding Index76.376.9GPT-6 Astra
LiveCodeBench (Vals AI)89.5%Not measuredOnly Gemini 3.8 Flash measured
SWE-bench Verified (Vals AI)80.0%Not measuredOnly Gemini 3.8 Flash measured
Terminal-Bench 4 (Vals AI)19.7%59.6%GPT-6 Astra
Vibe Code Bench (Vals AI)78.7%89.6%GPT-6 Astra
Code migration (Vals AI)36.5%67.7%GPT-6 Astra
ProgramBench (Vals AI)1.0%5.5%GPT-6 Astra
IOI (Vals AI)56.9%100.0%GPT-6 Astra
Terminal-Bench 2.1 (Vals AI)81.3%87.3%GPT-6 Astra
SWE-bench Multimodal (Vals AI)40.8%43.3%GPT-6 Astra
Vibe Code Bench 1-100 (Vals AI)18.8%27.6%GPT-6 Astra
SkillsBench (Vals AI)58.0%Not measuredOnly Gemini 3.8 Flash measured
CyberBench (Vals AI)43.8%41.1%Gemini 3.8 Flash
SciCode56.6%56.5%Gemini 3.8 Flash
FrontierCode41.2%53.3%GPT-6 Astra
FrontierSWE19.6%65.5%GPT-6 Astra
GSO-BenchNot measured79.4%Only GPT-6 Astra measured
WeirdML84.8%93.3%GPT-6 Astra
MirrorCodeNot measured46.7%Only GPT-6 Astra measured
ALE-Bench1269.72951.3GPT-6 Astra
LMArena Text: coding15081489Gemini 3.8 Flash
LMArena Text: software and IT15071474Gemini 3.8 Flash
LMArena WebDev: React15771798GPT-6 Astra
LMArena WebDev: HTML16161775GPT-6 Astra
LMArena WebDev: from an image15931726GPT-6 Astra
SciCode12.3%12.3%Tie
Neither model has a result on the other 11 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
AA Intelligence Index40.952.7GPT-6 Astra
Epoch Capabilities Index157.4168.8GPT-6 Astra
Agentic workLike-for-likePublic boards, shown as published, kept out of the index420
Agentic work benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
AA Agentic Index40.251.0GPT-6 Astra
Design Arena: agents building web apps12381373GPT-6 Astra
Design Arena: agents building full-stack apps12441357GPT-6 Astra
Design Arena: agents building mobile apps12361312GPT-6 Astra
Design Arena: agents building Android apps1078Not measuredOnly Gemini 3.8 Flash measured
Design Arena: agents building Godot games12731348GPT-6 Astra
Design Arena: PowerPoint slides11531219GPT-6 Astra
Design Arena: spreadsheets10221365GPT-6 Astra
LiveBench research79.1%85.2%GPT-6 Astra
LiveBench browser64.0%84.0%GPT-6 Astra
LiveBench long agentic30.1%82.4%GPT-6 Astra
SREBench (Vals AI)11.1%56.9%GPT-6 Astra
Finance Agent (Vals AI)61.4%53.5%Gemini 3.8 Flash
Tax Agent Bench (Vals AI)32.1%20.7%Gemini 3.8 Flash
Legal Research Bench (Vals AI)38.9%39.4%GPT-6 Astra
Harvey's Legal Agent Benchmark (Vals AI)12.1%7.1%Gemini 3.8 Flash
Excel Modeling Benchmark (Vals AI)72.2%71.7%Gemini 3.8 Flash
BioMysteryBench (Vals AI)62.2%79.3%GPT-6 Astra
Terminal-Bench-Science (Vals AI)8.6%62.9%GPT-6 Astra
Vals Science Index35.8%65.1%GPT-6 Astra
Time Horizon Index (Vals AI)18.8%90.5%GPT-6 Astra
CUA-bench (Vals AI)4.2%19.2%GPT-6 Astra
Robo-bench (Vals AI)Not measured23.3%Only GPT-6 Astra measured
APEX-Agents64.3%64.7%GPT-6 Astra
Remote Labor Index5.8%20.8%GPT-6 Astra
BALROGNot measured68.3%Only GPT-6 Astra measured
SpireClimbNot measured25.7%Only GPT-6 Astra measured
Vending-Bench 2$5,094$15,515GPT-6 Astra
Neither model has a result on the other 13 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index58
Reasoning benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
GPQA Diamond94.4%Not measuredOnly Gemini 3.8 Flash measured
LiveBench reasoning89.3%92.7%GPT-6 Astra
MysteryMechanism (Vals AI)36.5%53.1%GPT-6 Astra
MMMU Pro (Vals AI)89.1%Not measuredOnly Gemini 3.8 Flash measured
GPQA Diamond (Artificial Analysis run)95.3%96.3%GPT-6 Astra
Humanity's Last Exam (Artificial Analysis run)47.8%54.7%GPT-6 Astra
GPQA Diamond (Epoch AI run)95.4%95.8%GPT-6 Astra
ARC-AGI98.5%98.5%Tie
ARC-AGI-289.2%95.0%GPT-6 Astra
Chess puzzles58.0%74.0%GPT-6 Astra
Mystery game puzzles47.0%84.0%GPT-6 Astra
EBR-benchNot measured76.2%Only GPT-6 Astra measured
LMArena Text: hard prompts15091463Gemini 3.8 Flash
LMArena Text: expert15261489Gemini 3.8 Flash
LMArena Text: hard prompts in English15041464Gemini 3.8 Flash
LMArena Vision: diagrams13451297Gemini 3.8 Flash
LMArena Vision: homework13511337Gemini 3.8 Flash
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index24
Math benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
OTIS Mock AIME98.9%100.0%GPT-6 Astra
FrontierMath, tiers 1 to 368.4%93.7%GPT-6 Astra
FrontierMath, tier 422.0%97.6%GPT-6 Astra
ProofBench48.0%99.0%GPT-6 Astra
LMArena Text: math15321465Gemini 3.8 Flash
LMArena Text: mathematical work15191484Gemini 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 index43
Knowledge benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
MMLU Pro90.2%Not measuredOnly Gemini 3.8 Flash measured
LegalBench (Vals AI)87.0%Not measuredOnly Gemini 3.8 Flash measured
TaxEval (Vals AI)74.5%Not measuredOnly Gemini 3.8 Flash measured
MortgageTax (Vals AI)65.3%Not measuredOnly Gemini 3.8 Flash measured
MedCode (Vals AI)48.1%48.5%GPT-6 Astra
SimpleQA Verified69.7%75.6%GPT-6 Astra
LMArena Text: science15231451Gemini 3.8 Flash
LMArena Text: medicine and healthcare15081425Gemini 3.8 Flash
LMArena Text: legal and government14971462Gemini 3.8 Flash
LMArena Text: business and finance14791439Gemini 3.8 Flash
FACTS Benchmark Suite69.4%75.7%GPT-6 Astra
Neither model has a result on the other 7 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index09
Web design benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
Design Arena: websites13001336GPT-6 Astra
Design Arena: UI components13161393GPT-6 Astra
Design Arena: game dev13041478GPT-6 Astra
Design Arena: data viz12701335GPT-6 Astra
Design Arena: 3D12941500GPT-6 Astra
Design Arena: all code categories13031379GPT-6 Astra
Design Arena: SVG12961431GPT-6 Astra
Design Arena: ASCII art12621353GPT-6 Astra
LiveBench design72.7%82.0%GPT-6 Astra
GeneralLike-for-likePublic boards, shown as published, kept out of the index237
General benchmarks for Gemini 3.8 Flash and GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
Vals Index56.0%65.0%GPT-6 Astra
LiveBench data analysis54.0%83.0%GPT-6 Astra
Public Benefits Bench (Vals AI)65.3%Not measuredOnly Gemini 3.8 Flash measured
SAGE (Vals AI)35.1%46.4%GPT-6 Astra
MedScribe (Vals AI)84.5%87.9%GPT-6 Astra
Long context reasoning (AA-LCR)84.0%80.7%Gemini 3.8 Flash
DTBench95.7%97.3%GPT-6 Astra
LMCA52.9%64.4%GPT-6 Astra
Surface Evolver Bench76.9%Not measuredOnly Gemini 3.8 Flash measured
Furniture assembly31.7%80.0%GPT-6 Astra
LMArena Text14991441Gemini 3.8 Flash
LMArena Text: instruction following14921455Gemini 3.8 Flash
LMArena Text: creative writing14881420Gemini 3.8 Flash
LMArena Vision13151280Gemini 3.8 Flash
LMArena Text: English14981447Gemini 3.8 Flash
LMArena Text: non-English14911432Gemini 3.8 Flash
LMArena Text: Chinese15531489Gemini 3.8 Flash
LMArena Text: German15011459Gemini 3.8 Flash
LMArena Text: Japanese15071405Gemini 3.8 Flash
LMArena Text: Korean14641428Gemini 3.8 Flash
LMArena Text: French14961432Gemini 3.8 Flash
LMArena Text: Spanish14871422Gemini 3.8 Flash
LMArena Text: Russian15141438Gemini 3.8 Flash
LMArena Text: Polish14971422Gemini 3.8 Flash
LMArena Text: multi-turn15031447Gemini 3.8 Flash
LMArena Text: longer queries15071460Gemini 3.8 Flash
LMArena Text: writing and language14941437Gemini 3.8 Flash
LMArena Text: entertainment and media14801427Gemini 3.8 Flash
LMArena Vision: English13181280Gemini 3.8 Flash
LMArena Vision: Chinese14161361Gemini 3.8 Flash
LMArena Vision: reading text13331292Gemini 3.8 Flash
LMArena Vision: humor1321Not measuredOnly Gemini 3.8 Flash measured
LMArena Vision: creative writing12991286Gemini 3.8 Flash
Neither model has a result on the other 13 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 GPT-6 Astra
BenchmarkGemini 3.8 FlashGPT-6 AstraLeader
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$0.0026Fits in one request
GPT-6 Astra$0.035Fits in one request

Gemini 3.8 Flash costs less

Repository review

50K input + 3K output tokens

Gemini 3.8 Flash$0.049Fits in one request
GPT-6 Astra$0.650Fits in one request

Gemini 3.8 Flash costs less

Agent loop

200K input + 10K output tokens

Gemini 3.8 Flash$0.188Fits in one request
GPT-6 Astra$2.50Fits 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 3.8 Flash and GPT-6 Astra
SpecificationGoogle Gemini 3.8 FlashOpenAI GPT-6 Astra
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 2, 2026September 4, 2026
Context window1.05M1.05M
Input $/Mtok$0.75$10.00
Output $/Mtok$3.75$50.00
Coding index61.685.1
Independent measurements behind it65
Cost per solved task$2.74Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.8 Flash better than GPT-6 Astra for coding?

Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 61.6 for Gemini 3.8 Flash, though on 5 benchmarks against 6. Pick Gemini 3.8 Flash for output tokens 13.3x cheaper ($3.75 vs $50.00 per million) and work measured by CyberBench (Vals AI) or SciCode, where it leads.

Which is cheaper, Gemini 3.8 Flash or GPT-6 Astra?

Gemini 3.8 Flash costs $0.75 per million input tokens and $3.75 per million output tokens; GPT-6 Astra costs $10.00 and $50.00. Cost per solved task is known for Gemini 3.8 Flash only.

Which has the bigger context window, Gemini 3.8 Flash or GPT-6 Astra?

GPT-6 Astra, with 1.05M tokens against 1.05M.

How many benchmarks is the Gemini 3.8 Flash vs GPT-6 Astra comparison based on?

115 benchmarks have a result for both models as of October 22, 2026. Gemini 3.8 Flash's coding index rests on 6 independent benchmarks and GPT-6 Astra's on 5. Where only one model has a result, the page says so instead of naming a winner.

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