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DeepSeek V4 Flash 0423 vs GPT-5 Nano

Updated October 21, 2026. 38 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace DeepSeek V4 Flash 0423 Replace GPT-5 Nano
DeepSeek V4 Flash 0423DeepSeek
Coding
54.6
Overall
24.4
Output $/M
$0.182
38
GPT-5 NanoOpenAI
Coding
34.8
Overall
13.0
Output $/M
$0.40
0
vs boards won of 38 shared

Decision reading

Pick DeepSeek V4 Flash 0423 for coding: it scores 54.6 on the Vibe Coding Index against 34.8 for GPT-5 Nano.

GPT-5 Nano is neither cheaper nor larger in context, and leads no benchmark both models were measured on.

Model ADeepSeek V4 Flash 0423DeepSeek54.6/1001 independent benchmarkNo cost per solved taskModel BGPT-5 NanoOpenAI34.8/1001 independent benchmark$0.109 per solved task
Shared results
38
DeepSeek V4 Flash 0423 only
10
GPT-5 Nano only
47
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.

At a glance

Coding index
DeepSeek V4 Flash 0423 54.6 from 1 benchmark, GPT-5 Nano 34.8 from 1 benchmark.
Widest category
General, 20.7 points apart on average over 18 shared benchmarks.
Widest single gap
LMCA: DeepSeek V4 Flash 0423 35.9% against GPT-5 Nano 7.9%, 28.0 points apart on a 0 to 100 scale.
Output price
DeepSeek V4 Flash 0423 $0.182 against GPT-5 Nano $0.40 per million output tokens, 2.2x apart.
Context window
DeepSeek V4 Flash 0423 takes 1.05M tokens, GPT-5 Nano 400K.

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 Flash 0423BarsGPT-5 NanoTies
Coding30
Intelligence20
Reasoning30
Math20
Knowledge40
Web design60
General180
All shared boards380
CodingLike-for-likeFour of these boards feed the Vibe Coding Index30
Coding benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
SWE-bench VerifiedNot measured34.8%Only GPT-5 Nano measured
LMArena WebDev1582Not measuredOnly DeepSeek V4 Flash 0423 measured
AA Coding Index52.0Not measuredOnly DeepSeek V4 Flash 0423 measured
LiveCodeBench (Vals AI)Not measured70.2%Only GPT-5 Nano measured
LiveCodeBench (Artificial Analysis run)Not measured78.9%Only GPT-5 Nano measured
Terminal-Bench Hard (Artificial Analysis run)Not measured17.4%Only GPT-5 Nano measured
Terminal-BenchNot measured21.8%Only GPT-5 Nano measured
WeirdML45.6%38.1%DeepSeek V4 Flash 0423
ALE-Bench678.2Not measuredOnly DeepSeek V4 Flash 0423 measured
LMArena Text: coding14571351DeepSeek V4 Flash 0423
LMArena Text: software and IT14531345DeepSeek V4 Flash 0423
LMArena WebDev: React1585Not measuredOnly DeepSeek V4 Flash 0423 measured
LMArena WebDev: HTML1558Not measuredOnly DeepSeek V4 Flash 0423 measured
Neither model has a result on the other 25 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
AA Intelligence Index24.413.0DeepSeek V4 Flash 0423
Epoch Capabilities Index146.1139.2DeepSeek V4 Flash 0423
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
Agentic work benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
AA Agentic Index26.3Not measuredOnly DeepSeek V4 Flash 0423 measured
τ²-Bench TelecomNot measured36.5%Only GPT-5 Nano measured
Neither model has a result on the other 37 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index30
Reasoning benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
GPQA DiamondNot measured63.4%Only GPT-5 Nano measured
MMMU Pro (Vals AI)Not measured70.9%Only GPT-5 Nano measured
GPQA Diamond (Artificial Analysis run)Not measured67.6%Only GPT-5 Nano measured
Humanity's Last Exam (Artificial Analysis run)Not measured9.5%Only GPT-5 Nano measured
GPQA Diamond (Epoch AI run)Not measured69.4%Only GPT-5 Nano measured
ARC-AGINot measured20.7%Only GPT-5 Nano measured
ARC-AGI-2Not measured2.6%Only GPT-5 Nano measured
SimpleBench46.3%Not measuredOnly DeepSeek V4 Flash 0423 measured
Chess puzzlesNot measured22.0%Only GPT-5 Nano measured
Mystery game puzzlesNot measured9.0%Only GPT-5 Nano measured
VPCTNot measured37.2%Only GPT-5 Nano measured
LMArena Text: hard prompts14441328DeepSeek V4 Flash 0423
LMArena Text: expert14411321DeepSeek V4 Flash 0423
LMArena Text: hard prompts in English14491338DeepSeek V4 Flash 0423
LMArena Vision: diagramsNot measured1141Only GPT-5 Nano measured
LMArena Vision: homeworkNot measured1157Only GPT-5 Nano measured
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index20
Math benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
AIMENot measured81.2%Only GPT-5 Nano measured
MATH 500 (Vals AI)Not measured93.8%Only GPT-5 Nano measured
MGSM (Vals AI)Not measured89.3%Only GPT-5 Nano measured
AA Math IndexNot measured83.7Only GPT-5 Nano measured
AIME 2025 (Artificial Analysis run)Not measured83.7%Only GPT-5 Nano measured
OTIS Mock AIMENot measured81.1%Only GPT-5 Nano measured
FrontierMath, tiers 1 to 3Not measured20.0%Only GPT-5 Nano measured
FrontierMath, tier 4Not measured2.4%Only GPT-5 Nano measured
ProofBenchNot measured12.0%Only GPT-5 Nano measured
MATH level 5Not measured95.2%Only GPT-5 Nano measured
LMArena Text: math14261317DeepSeek V4 Flash 0423
LMArena Text: mathematical work14321326DeepSeek V4 Flash 0423
Neither model has a result on the other 1 board here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
Knowledge benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
MMLU ProNot measured76.1%Only GPT-5 Nano measured
LegalBench (Vals AI)Not measured50.1%Only GPT-5 Nano measured
CaseLaw (Vals AI)Not measured52.6%Only GPT-5 Nano measured
TaxEval (Vals AI)Not measured67.4%Only GPT-5 Nano measured
MortgageTax (Vals AI)Not measured53.6%Only GPT-5 Nano measured
MedQA (Vals AI)Not measured93.3%Only GPT-5 Nano measured
MedCode (Vals AI)Not measured30.4%Only GPT-5 Nano measured
MMLU Pro (Artificial Analysis run)Not measured78.0%Only GPT-5 Nano measured
SimpleQA VerifiedNot measured11.7%Only GPT-5 Nano measured
LMArena Text: science14461318DeepSeek V4 Flash 0423
LMArena Text: medicine and healthcare14481335DeepSeek V4 Flash 0423
LMArena Text: legal and government14391298DeepSeek V4 Flash 0423
LMArena Text: business and finance14251311DeepSeek V4 Flash 0423
Neither model has a result on the other 4 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index60
Web design benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
Design Arena: websites12081101DeepSeek V4 Flash 0423
Design Arena: UI components11641066DeepSeek V4 Flash 0423
Design Arena: game dev11971045DeepSeek V4 Flash 0423
Design Arena: data viz11271056DeepSeek V4 Flash 0423
Design Arena: 3D1189966DeepSeek V4 Flash 0423
Design Arena: all code categories12051084DeepSeek V4 Flash 0423
Design Arena: SVG1155Not measuredOnly DeepSeek V4 Flash 0423 measured
Design Arena: ASCII art1109Not measuredOnly DeepSeek V4 Flash 0423 measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index180
General benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
SAGE (Vals AI)Not measured30.4%Only GPT-5 Nano measured
MedScribe (Vals AI)Not measured72.9%Only GPT-5 Nano measured
IFBenchNot measured67.6%Only GPT-5 Nano measured
Long context reasoning (AA-LCR)Not measured45.0%Only GPT-5 Nano measured
DTBench86.4%62.7%DeepSeek V4 Flash 0423
LMCA35.9%7.9%DeepSeek V4 Flash 0423
Fiction.LiveBenchNot measured44.4%Only GPT-5 Nano measured
LMArena Text14321320DeepSeek V4 Flash 0423
LMArena Text: instruction following14211306DeepSeek V4 Flash 0423
LMArena Text: creative writing14031249DeepSeek V4 Flash 0423
LMArena VisionNot measured1159Only GPT-5 Nano measured
LMArena Text: English14411321DeepSeek V4 Flash 0423
LMArena Text: non-English14191313DeepSeek V4 Flash 0423
LMArena Text: Chinese14631356DeepSeek V4 Flash 0423
LMArena Text: German14191327DeepSeek V4 Flash 0423
LMArena Text: Japanese13891227DeepSeek V4 Flash 0423
LMArena Text: Korean13831269DeepSeek V4 Flash 0423
LMArena Text: French1439Not measuredOnly DeepSeek V4 Flash 0423 measured
LMArena Text: Spanish14361360DeepSeek V4 Flash 0423
LMArena Text: Russian14271296DeepSeek V4 Flash 0423
LMArena Text: Polish14361314DeepSeek V4 Flash 0423
LMArena Text: multi-turn14491311DeepSeek V4 Flash 0423
LMArena Text: longer queries14341312DeepSeek V4 Flash 0423
LMArena Text: writing and language14101283DeepSeek V4 Flash 0423
LMArena Text: entertainment and media14001268DeepSeek V4 Flash 0423
LMArena Vision: EnglishNot measured1170Only GPT-5 Nano measured
LMArena Vision: ChineseNot measured1176Only GPT-5 Nano measured
LMArena Vision: reading textNot measured1152Only GPT-5 Nano measured
LMArena Vision: humorNot measured1110Only GPT-5 Nano measured
Neither model has a result on the other 17 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for DeepSeek V4 Flash 0423 and GPT-5 Nano
BenchmarkDeepSeek V4 Flash 0423GPT-5 NanoLeader
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 Flash 0423$0.0002Fits in one request
GPT-5 Nano$0.0003Fits in one request

DeepSeek V4 Flash 0423 costs less

Repository review

50K input + 3K output tokens

DeepSeek V4 Flash 0423$0.0051Fits in one request
GPT-5 Nano$0.0037Fits in one request

GPT-5 Nano costs less

Agent loop

200K input + 10K output tokens

DeepSeek V4 Flash 0423$0.020Fits in one request
GPT-5 Nano$0.014Fits in one request

GPT-5 Nano 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 Flash 0423 and GPT-5 Nano
SpecificationDeepSeek V4 Flash 0423OpenAI GPT-5 Nano
MakerDeepSeekOpenAI
WeightsOpen weightsNo public weights listed
ReleasedApril 24, 2026August 7, 2025
Context window1.05M400K
Input $/Mtok$0.091$0.05
Output $/Mtok$0.182$0.40
Coding index54.634.8
Independent measurements behind it11
Cost per solved taskNot computable$0.109
SourceOpenRouter listingOpenRouter listing

Questions

Is DeepSeek V4 Flash 0423 better than GPT-5 Nano for coding?

Pick DeepSeek V4 Flash 0423 for coding: it scores 54.6 on the Vibe Coding Index against 34.8 for GPT-5 Nano. GPT-5 Nano is neither cheaper nor larger in context, and leads no benchmark both models were measured on.

Which is cheaper, DeepSeek V4 Flash 0423 or GPT-5 Nano?

DeepSeek V4 Flash 0423 costs $0.091 per million input tokens and $0.182 per million output tokens; GPT-5 Nano costs $0.05 and $0.40. Cost per solved task is known for GPT-5 Nano only.

Which has the bigger context window, DeepSeek V4 Flash 0423 or GPT-5 Nano?

DeepSeek V4 Flash 0423, with 1.05M tokens against 400K.

How many benchmarks is the DeepSeek V4 Flash 0423 vs GPT-5 Nano comparison based on?

38 benchmarks have a result for both models as of October 21, 2026. DeepSeek V4 Flash 0423's coding index rests on 1 independent benchmark and GPT-5 Nano's on 1. Where only one model has a result, the page says so instead of naming a winner.

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