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DeepSeek V4.1 Flash vs GPT-5.6 Luna

DeepSeek V4.1 Flash leads GPT-5.6 Luna on coding, 62.5 to 58.0 on the Vibe Coding Index, and DeepSeek V4.1 Flash costs 1.4x less per output token ($0.84 vs $1.20 per million). Updated October 22, 2026; 100 benchmarks have a result for both.

Replace DeepSeek V4.1 Flash Replace GPT-5.6 Luna
DeepSeek V4.1 FlashDeepSeek
Coding
62.5
Overall
62.4
Output $/M
$0.84
76
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
22
vs boards won of 100 shared, 2 tied

DeepSeek V4.1 Flash or GPT-5.6 Luna: which to pick

Pick DeepSeek V4.1 Flash for coding: it scores 62.5 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna, though on 5 benchmarks against 6.

Pick GPT-5.6 Luna for a larger context window (1.05M against 1.05M tokens) and work measured by IOI (Vals AI) or Terminal-Bench 2.1 (Vals AI), where it leads.

Model ADeepSeek V4.1 FlashDeepSeek62.5/1005 independent benchmarksNo cost per solved taskModel BGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task
Shared results
100
DeepSeek V4.1 Flash only
1
GPT-5.6 Luna only
19
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
DeepSeek V4.1 Flash 62.5 from 5 benchmarks, GPT-5.6 Luna 58.0 from 6 benchmarks.
Widest category
Web design, 11.9 points apart on average over 9 shared benchmarks.
Widest single gap
LiveBench research: DeepSeek V4.1 Flash 86.8% against GPT-5.6 Luna 51.0%, 35.8 points apart on a 0 to 100 scale.
Output price
DeepSeek V4.1 Flash $0.84 against GPT-5.6 Luna $1.20 per million output tokens, 1.4x apart.
Context window
DeepSeek V4.1 Flash takes 1.05M tokens, GPT-5.6 Luna 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
CategoryDeepSeek V4.1 FlashBarsGPT-5.6 LunaTies
Coding145
Intelligence02
Agentic work741 tie
Reasoning112
Math231 tie
Knowledge43
Web design90
General293
All shared boards76222 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index145
Coding benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
LiveBench coding90.2%73.6%DeepSeek V4.1 Flash
LMArena WebDev16181518DeepSeek V4.1 Flash
AA Coding IndexNot measured71.4Only GPT-5.6 Luna measured
SWE-bench Verified (Vals AI)Not measured93.0%Only GPT-5.6 Luna measured
Terminal-Bench 4 (Vals AI)19.7%11.6%DeepSeek V4.1 Flash
Vibe Code Bench (Vals AI)84.7%77.1%DeepSeek V4.1 Flash
Code migration (Vals AI)45.6%44.5%DeepSeek V4.1 Flash
ProgramBench (Vals AI)0.5%0.0%DeepSeek V4.1 Flash
IOI (Vals AI)40.3%61.8%GPT-5.6 Luna
Terminal-Bench 2.1 (Vals AI)74.5%79.0%GPT-5.6 Luna
SWE-bench Multimodal (Vals AI)46.5%Not measuredOnly DeepSeek V4.1 Flash measured
Vibe Code Bench 1-100 (Vals AI)16.4%22.6%GPT-5.6 Luna
SkillsBench (Vals AI)69.8%60.5%DeepSeek V4.1 Flash
CyberBench (Vals AI)73.7%73.6%DeepSeek V4.1 Flash
SciCode51.9%53.6%GPT-5.6 Luna
FrontierCode43.9%39.8%DeepSeek V4.1 Flash
WeirdMLNot measured60.9%Only GPT-5.6 Luna measured
ALE-Bench1092.31667.4GPT-5.6 Luna
LMArena Text: coding15021466DeepSeek V4.1 Flash
LMArena Text: software and IT14961463DeepSeek V4.1 Flash
LMArena WebDev: React16281508DeepSeek V4.1 Flash
LMArena WebDev: HTML16121520DeepSeek V4.1 Flash
LMArena WebDev: from an image16061517DeepSeek V4.1 Flash
SciCodeNot measured6.2%Only GPT-5.6 Luna measured
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
AA Intelligence Index24.737.3GPT-5.6 Luna
Epoch Capabilities Index155.9156.5GPT-5.6 Luna
Agentic workLike-for-likePublic boards, shown as published, kept out of the index74
Agentic work benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
AA Agentic IndexNot measured42.1Only GPT-5.6 Luna measured
LiveBench research86.8%51.0%DeepSeek V4.1 Flash
LiveBench browser84.0%68.0%DeepSeek V4.1 Flash
LiveBench long agentic40.1%30.4%DeepSeek V4.1 Flash
SREBench (Vals AI)0.8%1.5%GPT-5.6 Luna
Finance Agent (Vals AI)53.5%55.0%GPT-5.6 Luna
Tax Agent Bench (Vals AI)26.6%24.8%DeepSeek V4.1 Flash
Legal Research Bench (Vals AI)41.4%36.5%DeepSeek V4.1 Flash
Excel Modeling Benchmark (Vals AI)57.2%67.1%GPT-5.6 Luna
BioMysteryBench (Vals AI)67.8%61.5%DeepSeek V4.1 Flash
Terminal-Bench-Science (Vals AI)0.0%0.0%Tie
Vals Science Index29.6%25.3%DeepSeek V4.1 Flash
APEX-Agents39.5%43.0%GPT-5.6 Luna
BALROGNot measured45.6%Only GPT-5.6 Luna measured
Vending-Bench 2Not measured$4,095Only GPT-5.6 Luna measured
Neither model has a result on the other 26 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index112
Reasoning benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
GPQA DiamondNot measured91.7%Only GPT-5.6 Luna measured
LiveBench reasoning86.7%85.6%DeepSeek V4.1 Flash
MysteryMechanism (Vals AI)21.2%14.4%DeepSeek V4.1 Flash
MMMU Pro (Vals AI)Not measured85.0%Only GPT-5.6 Luna measured
GPQA Diamond (Artificial Analysis run)Not measured91.1%Only GPT-5.6 Luna measured
Humanity's Last Exam (Artificial Analysis run)39.2%39.5%GPT-5.6 Luna
GPQA Diamond (Epoch AI run)89.8%91.6%GPT-5.6 Luna
ARC-AGI94.5%88.0%DeepSeek V4.1 Flash
ARC-AGI-272.9%59.5%DeepSeek V4.1 Flash
SimpleBenchNot measured46.8%Only GPT-5.6 Luna measured
Chess puzzles48.0%43.0%DeepSeek V4.1 Flash
Mystery game puzzles43.0%21.0%DeepSeek V4.1 Flash
LMArena Text: hard prompts14831451DeepSeek V4.1 Flash
LMArena Text: expert15011478DeepSeek V4.1 Flash
LMArena Text: hard prompts in English14881460DeepSeek V4.1 Flash
LMArena Vision: diagrams12971273DeepSeek V4.1 Flash
LMArena Vision: homework13071282DeepSeek V4.1 Flash
Kagi LLM BenchmarkNot measured49.1%Only GPT-5.6 Luna measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index23
Math benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
OTIS Mock AIME98.3%98.3%Tie
FrontierMath, tiers 1 to 367.4%82.1%GPT-5.6 Luna
FrontierMath, tier 426.8%61.0%GPT-5.6 Luna
ProofBench54.0%60.0%GPT-5.6 Luna
LMArena Text: math14781459DeepSeek V4.1 Flash
LMArena Text: mathematical work14851470DeepSeek V4.1 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 DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
MMLU ProNot measured86.0%Only GPT-5.6 Luna measured
LegalBench (Vals AI)83.3%84.0%GPT-5.6 Luna
CorpFin (Vals AI)Not measured64.2%Only GPT-5.6 Luna measured
TaxEval (Vals AI)Not measured76.2%Only GPT-5.6 Luna measured
MortgageTax (Vals AI)Not measured67.3%Only GPT-5.6 Luna measured
MedCode (Vals AI)41.2%42.4%GPT-5.6 Luna
SimpleQA Verified42.9%41.0%DeepSeek V4.1 Flash
LMArena Text: science14691433DeepSeek V4.1 Flash
LMArena Text: medicine and healthcare14841399DeepSeek V4.1 Flash
LMArena Text: legal and government14431446GPT-5.6 Luna
LMArena Text: business and finance14611439DeepSeek V4.1 Flash
FACTS Benchmark SuiteNot measured35.0%Only GPT-5.6 Luna measured
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index90
Web design benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
Design Arena: websites13081255DeepSeek V4.1 Flash
Design Arena: UI components13121248DeepSeek V4.1 Flash
Design Arena: game dev13301194DeepSeek V4.1 Flash
Design Arena: data viz12911211DeepSeek V4.1 Flash
Design Arena: 3D13551121DeepSeek V4.1 Flash
Design Arena: all code categories13201231DeepSeek V4.1 Flash
Design Arena: SVG12451194DeepSeek V4.1 Flash
Design Arena: ASCII art12651142DeepSeek V4.1 Flash
LiveBench design79.2%76.0%DeepSeek V4.1 Flash
GeneralLike-for-likePublic boards, shown as published, kept out of the index293
General benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
LiveBench data analysis79.3%78.0%DeepSeek V4.1 Flash
Public Benefits Bench (Vals AI)64.3%61.2%DeepSeek V4.1 Flash
SAGE (Vals AI)47.9%44.2%DeepSeek V4.1 Flash
MedScribe (Vals AI)85.5%84.4%DeepSeek V4.1 Flash
Vals Multimodal IndexNot measured69.1%Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)84.0%83.7%DeepSeek V4.1 Flash
DTBench89.9%89.1%DeepSeek V4.1 Flash
LMCA47.0%48.5%GPT-5.6 Luna
Surface Evolver Bench46.3%61.9%GPT-5.6 Luna
Furniture assembly34.2%42.5%GPT-5.6 Luna
LMArena Text14641431DeepSeek V4.1 Flash
LMArena Text: instruction following14731437DeepSeek V4.1 Flash
LMArena Text: creative writing14371396DeepSeek V4.1 Flash
LMArena Vision12781257DeepSeek V4.1 Flash
LMArena Text: English14731441DeepSeek V4.1 Flash
LMArena Text: non-English14491417DeepSeek V4.1 Flash
LMArena Text: Chinese15011470DeepSeek V4.1 Flash
LMArena Text: German14701455DeepSeek V4.1 Flash
LMArena Text: Japanese14321415DeepSeek V4.1 Flash
LMArena Text: Korean14361415DeepSeek V4.1 Flash
LMArena Text: French14651458DeepSeek V4.1 Flash
LMArena Text: Spanish14591446DeepSeek V4.1 Flash
LMArena Text: Russian14671427DeepSeek V4.1 Flash
LMArena Text: Polish14571405DeepSeek V4.1 Flash
LMArena Text: multi-turn14611434DeepSeek V4.1 Flash
LMArena Text: longer queries14731436DeepSeek V4.1 Flash
LMArena Text: writing and language14501419DeepSeek V4.1 Flash
LMArena Text: entertainment and media14451402DeepSeek V4.1 Flash
LMArena Vision: English12881263DeepSeek V4.1 Flash
LMArena Vision: Chinese13271294DeepSeek V4.1 Flash
LMArena Vision: reading text12821264DeepSeek V4.1 Flash
LMArena Vision: humor12601190DeepSeek V4.1 Flash
LMArena Vision: creative writing12751257DeepSeek V4.1 Flash
LMArena DocumentNot measured1457Only GPT-5.6 Luna measured
Neither model has a result on the other 12 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for DeepSeek V4.1 Flash and GPT-5.6 Luna
BenchmarkDeepSeek V4.1 FlashGPT-5.6 LunaLeader
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

DeepSeek V4.1 Flash$0.0006Fits in one request
GPT-5.6 Luna$0.0008Fits in one request

DeepSeek V4.1 Flash costs less

Repository review

50K input + 3K output tokens

DeepSeek V4.1 Flash$0.014Fits in one request
GPT-5.6 Luna$0.014Fits in one request

GPT-5.6 Luna costs less

Agent loop

200K input + 10K output tokens

DeepSeek V4.1 Flash$0.053Fits in one request
GPT-5.6 Luna$0.052Fits in one request

GPT-5.6 Luna 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 DeepSeek V4.1 Flash and GPT-5.6 Luna
SpecificationDeepSeek V4.1 FlashOpenAI GPT-5.6 Luna
MakerDeepSeekOpenAI
WeightsOpen weightsNo public weights listed
ReleasedSeptember 10, 2026July 9, 2026
Context window1.05M1.05M
Input $/Mtok$0.2225$0.20
Output $/Mtok$0.84$1.20
Coding index62.558.0
Independent measurements behind it56
Cost per solved taskNot computable$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is DeepSeek V4.1 Flash better than GPT-5.6 Luna for coding?

Pick DeepSeek V4.1 Flash for coding: it scores 62.5 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna, though on 5 benchmarks against 6. Pick GPT-5.6 Luna for a larger context window (1.05M against 1.05M tokens) and work measured by IOI (Vals AI) or Terminal-Bench 2.1 (Vals AI), where it leads.

Which is cheaper, DeepSeek V4.1 Flash or GPT-5.6 Luna?

DeepSeek V4.1 Flash costs $0.2225 per million input tokens and $0.84 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Cost per solved task is known for GPT-5.6 Luna only.

Which has the bigger context window, DeepSeek V4.1 Flash or GPT-5.6 Luna?

GPT-5.6 Luna, with 1.05M tokens against 1.05M.

How many benchmarks is the DeepSeek V4.1 Flash vs GPT-5.6 Luna comparison based on?

100 benchmarks have a result for both models as of October 22, 2026. DeepSeek V4.1 Flash's coding index rests on 5 independent benchmarks and GPT-5.6 Luna'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/deepseek-v4-1-flash-vs-gpt-5-6-luna">LLMBenchmark.ai, DeepSeek V4.1 Flash vs GPT-5.6 Luna</a></p>