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GPT-5.3-Codex vs Grok 4.3

GPT-5.3-Codex leads Grok 4.3 on coding, 60.0 to 37.4 on the Vibe Coding Index, and Grok 4.3 costs 5.6x less per output token ($2.50 vs $14.00 per million). Updated October 22, 2026; 30 benchmarks have a result for both.

Replace GPT-5.3-Codex Replace Grok 4.3
GPT-5.3-CodexOpenAI
Coding
60.0
Overall
No data
Output $/M
$14.00
19
Grok 4.3xAI
Coding
37.4
Overall
53.1
Output $/M
$2.50
11
vs boards won of 30 shared

GPT-5.3-Codex or Grok 4.3: which to pick

Pick GPT-5.3-Codex for coding: it scores 60.0 on the Vibe Coding Index against 37.4 for Grok 4.3.

Pick Grok 4.3 for output tokens 5.6x cheaper ($2.50 vs $14.00 per million) and a lower cost per solved task ($0.31 against $0.59).

Model AGPT-5.3-CodexOpenAI60.0/1003 independent benchmarks$0.59 per solved taskModel BGrok 4.3xAI37.4/1003 independent benchmarks$0.31 per solved task
Shared results
30
GPT-5.3-Codex only
4
Grok 4.3 only
75
Like-for-like categories
6 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
GPT-5.3-Codex 60.0 from 3 benchmarks, Grok 4.3 37.4 from 3 benchmarks.
Widest category
Coding, 15.5 points apart on average over 10 shared benchmarks.
Widest single gap
Vibe Code Bench (Vals AI): GPT-5.3-Codex 61.8% against Grok 4.3 19.4%, 42.4 points apart on a 0 to 100 scale.
Output price
GPT-5.3-Codex $14.00 against Grok 4.3 $2.50 per million output tokens, 5.6x apart.
Context window
GPT-5.3-Codex takes 400K tokens, Grok 4.3 1M.

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
CategoryGPT-5.3-CodexBarsGrok 4.3Ties
Coding100
Intelligence10
Agentic work34
Reasoning20
Web design26
General11
All shared boards1911
CodingLike-for-likeSix of these boards feed the Vibe Coding Index100
Coding benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
LMArena WebDev14071358GPT-5.3-Codex
AA Coding IndexNot measured42.2Only Grok 4.3 measured
LiveCodeBench (Vals AI)87.3%84.5%GPT-5.3-Codex
SWE-bench Verified (Vals AI)78.0%71.4%GPT-5.3-Codex
Vibe Code Bench (Vals AI)61.8%19.4%GPT-5.3-Codex
Code migration (Vals AI)Not measured6.8%Only Grok 4.3 measured
ProgramBench (Vals AI)Not measured0.0%Only Grok 4.3 measured
IOI (Vals AI)53.8%Not measuredOnly GPT-5.3-Codex measured
Terminal-Bench 2.1 (Vals AI)Not measured42.0%Only Grok 4.3 measured
SkillsBench (Vals AI)Not measured40.6%Only Grok 4.3 measured
SciCodeNot measured48.3%Only Grok 4.3 measured
Terminal-Bench Hard (Artificial Analysis run)53.0%37.9%GPT-5.3-Codex
Terminal-Bench78.4%Not measuredOnly GPT-5.3-Codex measured
WeirdML79.3%49.9%GPT-5.3-Codex
ALE-Bench1655.2944.2GPT-5.3-Codex
LMArena Text: codingNot measured1415Only Grok 4.3 measured
LMArena Text: software and ITNot measured1416Only Grok 4.3 measured
LMArena WebDev: React13951353GPT-5.3-Codex
LMArena WebDev: HTML14221367GPT-5.3-Codex
LMArena WebDev: from an image14431375GPT-5.3-Codex
Neither model has a result on the other 19 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
AA Intelligence Index32.524.9GPT-5.3-Codex
Epoch Capabilities Index157.1Not measuredOnly GPT-5.3-Codex measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index34
Agentic work benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
AA Agentic IndexNot measured15.5Only Grok 4.3 measured
Design Arena: agents building web apps10321126Grok 4.3
Design Arena: agents building full-stack apps9831006Grok 4.3
Design Arena: agents building mobile apps10531058Grok 4.3
Design Arena: agents building Android apps1084962GPT-5.3-Codex
Design Arena: agents building Godot games1124914GPT-5.3-Codex
Design Arena: agents building gamesNot measured1007Only Grok 4.3 measured
Design Arena: HTML slidesNot measured959Only Grok 4.3 measured
Design Arena: PowerPoint slidesNot measured988Only Grok 4.3 measured
Design Arena: spreadsheetsNot measured879Only Grok 4.3 measured
Finance Agent (Vals AI)Not measured37.7%Only Grok 4.3 measured
Tax Agent Bench (Vals AI)Not measured6.2%Only Grok 4.3 measured
Legal Research Bench (Vals AI)Not measured15.4%Only Grok 4.3 measured
Excel Modeling Benchmark (Vals AI)Not measured18.4%Only Grok 4.3 measured
τ²-Bench Telecom86.0%97.7%Grok 4.3
METR time horizons74.5%Not measuredOnly GPT-5.3-Codex measured
Vending-Bench 2$5,940$35GPT-5.3-Codex
LMArena SearchNot measured1166Only Grok 4.3 measured
Neither model has a result on the other 23 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index20
Reasoning benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
GPQA DiamondNot measured91.4%Only Grok 4.3 measured
MMMU Pro (Vals AI)Not measured83.1%Only Grok 4.3 measured
GPQA Diamond (Artificial Analysis run)91.5%90.1%GPT-5.3-Codex
Humanity's Last Exam (Artificial Analysis run)42.5%37.2%GPT-5.3-Codex
GPQA Diamond (Epoch AI run)Not measured88.8%Only Grok 4.3 measured
Chess puzzlesNot measured18.0%Only Grok 4.3 measured
LMArena Text: hard promptsNot measured1396Only Grok 4.3 measured
LMArena Text: expertNot measured1384Only Grok 4.3 measured
LMArena Text: hard prompts in EnglishNot measured1402Only Grok 4.3 measured
LMArena Vision: diagramsNot measured1241Only Grok 4.3 measured
LMArena Vision: homeworkNot measured1241Only Grok 4.3 measured
Neither model has a result on the other 11 boards here
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
Math benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
OTIS Mock AIMENot measured93.3%Only Grok 4.3 measured
FrontierMath, tiers 1 to 3Not measured42.8%Only Grok 4.3 measured
FrontierMath, tier 4Not measured14.6%Only Grok 4.3 measured
ProofBenchNot measured11.0%Only Grok 4.3 measured
LMArena Text: mathNot measured1387Only Grok 4.3 measured
LMArena Text: mathematical workNot measured1396Only Grok 4.3 measured
Neither model has a result on the other 7 boards here
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
Knowledge benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
MMLU ProNot measured85.8%Only Grok 4.3 measured
LegalBench (Vals AI)Not measured84.5%Only Grok 4.3 measured
CaseLaw (Vals AI)Not measured79.3%Only Grok 4.3 measured
CorpFin (Vals AI)Not measured68.5%Only Grok 4.3 measured
TaxEval (Vals AI)Not measured70.8%Only Grok 4.3 measured
MortgageTax (Vals AI)Not measured48.3%Only Grok 4.3 measured
MedCode (Vals AI)Not measured38.1%Only Grok 4.3 measured
SimpleQA VerifiedNot measured33.2%Only Grok 4.3 measured
LMArena Text: scienceNot measured1399Only Grok 4.3 measured
LMArena Text: medicine and healthcareNot measured1384Only Grok 4.3 measured
LMArena Text: legal and governmentNot measured1386Only Grok 4.3 measured
LMArena Text: business and financeNot measured1381Only Grok 4.3 measured
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index26
Web design benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
Design Arena: websites11621196Grok 4.3
Design Arena: UI components11341190Grok 4.3
Design Arena: game dev11611173Grok 4.3
Design Arena: data viz11641179Grok 4.3
Design Arena: 3D10071124Grok 4.3
Design Arena: all code categories11441186Grok 4.3
Design Arena: SVG11291080GPT-5.3-Codex
Design Arena: ASCII art11521125GPT-5.3-Codex
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index11
General benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
Public Benefits Bench (Vals AI)Not measured51.7%Only Grok 4.3 measured
SAGE (Vals AI)Not measured19.7%Only Grok 4.3 measured
MedScribe (Vals AI)Not measured74.4%Only Grok 4.3 measured
Vals Multimodal IndexNot measured43.3%Only Grok 4.3 measured
IFBench75.4%83.3%Grok 4.3
Long context reasoning (AA-LCR)83.3%75.0%GPT-5.3-Codex
DTBenchNot measured90.7%Only Grok 4.3 measured
LMCANot measured38.3%Only Grok 4.3 measured
LMArena TextNot measured1397Only Grok 4.3 measured
LMArena Text: instruction followingNot measured1366Only Grok 4.3 measured
LMArena Text: creative writingNot measured1380Only Grok 4.3 measured
LMArena VisionNot measured1229Only Grok 4.3 measured
LMArena Text: EnglishNot measured1404Only Grok 4.3 measured
LMArena Text: non-EnglishNot measured1385Only Grok 4.3 measured
LMArena Text: ChineseNot measured1422Only Grok 4.3 measured
LMArena Text: GermanNot measured1395Only Grok 4.3 measured
LMArena Text: JapaneseNot measured1379Only Grok 4.3 measured
LMArena Text: KoreanNot measured1354Only Grok 4.3 measured
LMArena Text: FrenchNot measured1411Only Grok 4.3 measured
LMArena Text: SpanishNot measured1399Only Grok 4.3 measured
LMArena Text: RussianNot measured1399Only Grok 4.3 measured
LMArena Text: PolishNot measured1398Only Grok 4.3 measured
LMArena Text: multi-turnNot measured1406Only Grok 4.3 measured
LMArena Text: longer queriesNot measured1393Only Grok 4.3 measured
LMArena Text: writing and languageNot measured1385Only Grok 4.3 measured
LMArena Text: entertainment and mediaNot measured1370Only Grok 4.3 measured
LMArena Vision: EnglishNot measured1235Only Grok 4.3 measured
LMArena Vision: ChineseNot measured1257Only Grok 4.3 measured
LMArena Vision: reading textNot measured1235Only Grok 4.3 measured
LMArena Vision: humorNot measured1222Only Grok 4.3 measured
LMArena Vision: recognizing thingsNot measured1217Only Grok 4.3 measured
LMArena Vision: creative writingNot measured1237Only Grok 4.3 measured
Neither model has a result on the other 14 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5.3-Codex and Grok 4.3
BenchmarkGPT-5.3-CodexGrok 4.3Leader
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

GPT-5.3-Codex$0.0088Fits in one request
Grok 4.3$0.0025Fits in one request

Grok 4.3 costs less

Repository review

50K input + 3K output tokens

GPT-5.3-Codex$0.130Fits in one request
Grok 4.3$0.070Fits in one request

Grok 4.3 costs less

Agent loop

200K input + 10K output tokens

GPT-5.3-Codex$0.490Fits in one request
Grok 4.3$0.275Fits in one request

Grok 4.3 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 GPT-5.3-Codex and Grok 4.3
SpecificationOpenAI GPT-5.3-CodexSpaceXAI Grok 4.3
MakerOpenAIxAI
WeightsNo public weights listedNo public weights listed
ReleasedFebruary 24, 2026April 30, 2026
Context window400K1M
Input $/Mtok$1.75$1.25
Output $/Mtok$14.00$2.50
Coding index60.037.4
Independent measurements behind it33
Cost per solved task$0.59$0.31
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.3-Codex better than Grok 4.3 for coding?

Pick GPT-5.3-Codex for coding: it scores 60.0 on the Vibe Coding Index against 37.4 for Grok 4.3. Pick Grok 4.3 for output tokens 5.6x cheaper ($2.50 vs $14.00 per million) and a lower cost per solved task ($0.31 against $0.59).

Which is cheaper, GPT-5.3-Codex or Grok 4.3?

GPT-5.3-Codex costs $1.75 per million input tokens and $14.00 per million output tokens; Grok 4.3 costs $1.25 and $2.50. Per solved SWE-bench Verified task, GPT-5.3-Codex costs $0.59 and Grok 4.3 $0.31.

Which has the bigger context window, GPT-5.3-Codex or Grok 4.3?

Grok 4.3, with 1M tokens against 400K.

How many benchmarks is the GPT-5.3-Codex vs Grok 4.3 comparison based on?

30 benchmarks have a result for both models as of October 22, 2026. GPT-5.3-Codex's coding index rests on 3 independent benchmarks and Grok 4.3's on 3. Where only one model has a result, the page says so instead of naming a winner.

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