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GPT-5 vs Grok 4.20

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 GPT-5 Replace Grok 4.20
GPT-5OpenAI
Coding
38.8
Overall
23.0
Output $/M
$10.00
16
Grok 4.20xAI
Coding
33.3
Overall
25.7
Output $/M
$2.50
21
vs boards won of 38 shared, 1 tied

Decision reading

Pick GPT-5 for coding: it scores 38.8 on the Vibe Coding Index against 33.3 for Grok 4.20.

Pick Grok 4.20 when output tokens cost 4.0x less, or when the context window is larger, 2M against 400K tokens.

Model AGPT-5OpenAI38.8/1003 independent benchmarks$0.39 per solved taskModel BGrok 4.20xAI33.3/1002 independent benchmarks$0.72 per solved task
Shared results
38
GPT-5 only
71
Grok 4.20 only
16
Like-for-like categories
8 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
GPT-5 38.8 from 3 benchmarks, Grok 4.20 33.3 from 2 benchmarks.
Widest category
Reasoning, 16.0 points apart on average over 6 shared benchmarks.
Widest single gap
ARC-AGI-2: GPT-5 9.9% against Grok 4.20 65.1%, 55.3 points apart on a 0 to 100 scale.
Output price
GPT-5 $10.00 against Grok 4.20 $2.50 per million output tokens, 4.0x apart.
Context window
GPT-5 takes 400K tokens, Grok 4.20 2M.

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-5BarsGrok 4.20Ties
Coding321 tie
Intelligence02
Agentic work01
Reasoning06
Math01
Knowledge62
Web design26
General51
All shared boards16211 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index32
Coding benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
Aider polyglot88.0%Not measuredOnly GPT-5 measured
SWE-bench Verified74.4%Not measuredOnly GPT-5 measured
LMArena WebDev1418Not measuredOnly GPT-5 measured
AA Coding Index37.8Not measuredOnly GPT-5 measured
LiveCodeBench (Vals AI)85.9%84.3%GPT-5
SWE-bench Verified (Vals AI)69.0%72.2%Grok 4.20
Vibe Code Bench (Vals AI)20.1%4.1%GPT-5
Code migration (Vals AI)Not measured0.3%Only Grok 4.20 measured
Terminal-Bench 2.1 (Vals AI)Not measured44.2%Only Grok 4.20 measured
LiveCodeBench (Artificial Analysis run)84.6%Not measuredOnly GPT-5 measured
Terminal-Bench Hard (Artificial Analysis run)37.9%37.9%Tie
Terminal-Bench49.6%57.3%Grok 4.20
GSO-Bench6.9%Not measuredOnly GPT-5 measured
WeirdML60.7%52.3%GPT-5
ALE-Bench807.6Not measuredOnly GPT-5 measured
LMArena Text: coding1436Not measuredOnly GPT-5 measured
LMArena Text: software and IT1420Not measuredOnly GPT-5 measured
LMArena WebDev: HTML1427Not measuredOnly GPT-5 measured
Neither model has a result on the other 20 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
AA Intelligence Index23.025.7Grok 4.20
Epoch Capabilities Index150.0152.1Grok 4.20
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
Agentic work benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
Design Arena: agents building web appsNot measured1144Only Grok 4.20 measured
Design Arena: agents building full-stack appsNot measured1054Only Grok 4.20 measured
Design Arena: agents building mobile appsNot measured1090Only Grok 4.20 measured
Design Arena: agents building Android appsNot measured1052Only Grok 4.20 measured
Design Arena: agents building Godot gamesNot measured1089Only Grok 4.20 measured
Design Arena: HTML slidesNot measured1180Only Grok 4.20 measured
Finance Agent (Vals AI)Not measured28.5%Only Grok 4.20 measured
Tax Agent Bench (Vals AI)Not measured7.0%Only Grok 4.20 measured
Legal Research Bench (Vals AI)Not measured13.9%Only Grok 4.20 measured
Excel Modeling Benchmark (Vals AI)Not measured11.7%Only Grok 4.20 measured
τ²-Bench Telecom86.5%93.0%Grok 4.20
METR time horizons69.6%Not measuredOnly GPT-5 measured
Remote Labor Index1.7%Not measuredOnly GPT-5 measured
GDPval34.8%Not measuredOnly GPT-5 measured
BALROG32.8%Not measuredOnly GPT-5 measured
DeepResearch Bench49.6%Not measuredOnly GPT-5 measured
Vending-Bench 2Not measured$4,663Only Grok 4.20 measured
Neither model has a result on the other 22 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index06
Reasoning benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
GPQA Diamond85.6%88.6%Grok 4.20
MMMU Pro (Vals AI)81.5%83.5%Grok 4.20
GPQA Diamond (Artificial Analysis run)85.4%91.1%Grok 4.20
Humanity's Last Exam (Artificial Analysis run)28.5%34.5%Grok 4.20
GPQA Diamond (Epoch AI run)86.2%Not measuredOnly GPT-5 measured
ARC-AGI65.7%89.5%Grok 4.20
ARC-AGI-29.9%65.1%Grok 4.20
SimpleBench56.7%Not measuredOnly GPT-5 measured
Chess puzzles36.0%Not measuredOnly GPT-5 measured
Mystery game puzzles23.0%Not measuredOnly GPT-5 measured
EBR-bench12.7%Not measuredOnly GPT-5 measured
VPCT66.0%Not measuredOnly GPT-5 measured
LMArena Text: hard prompts1415Not measuredOnly GPT-5 measured
LMArena Text: expert1419Not measuredOnly GPT-5 measured
LMArena Text: hard prompts in English1419Not measuredOnly GPT-5 measured
LMArena Vision: diagrams1252Not measuredOnly GPT-5 measured
LMArena Vision: homework1278Not measuredOnly GPT-5 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index01
Math benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
AIME93.4%96.5%Grok 4.20
MATH 500 (Vals AI)96.0%Not measuredOnly GPT-5 measured
MGSM (Vals AI)92.8%Not measuredOnly GPT-5 measured
AA Math Index94.3Not measuredOnly GPT-5 measured
AIME 2025 (Artificial Analysis run)94.3%Not measuredOnly GPT-5 measured
OTIS Mock AIME91.4%Not measuredOnly GPT-5 measured
FrontierMath, tiers 1 to 355.4%Not measuredOnly GPT-5 measured
FrontierMath, tier 422.0%Not measuredOnly GPT-5 measured
ProofBench18.0%Not measuredOnly GPT-5 measured
MATH level 598.1%Not measuredOnly GPT-5 measured
LMArena Text: math1407Not measuredOnly GPT-5 measured
LMArena Text: mathematical work1405Not measuredOnly GPT-5 measured
Neither model has a result on the other 1 board here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index62
Knowledge benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
MMLU Pro86.5%86.3%GPT-5
LegalBench (Vals AI)86.0%77.7%GPT-5
CaseLaw (Vals AI)66.5%54.4%GPT-5
CorpFin (Vals AI)61.1%63.7%Grok 4.20
TaxEval (Vals AI)73.4%74.1%Grok 4.20
MortgageTax (Vals AI)65.5%45.4%GPT-5
MedQA (Vals AI)96.3%94.5%GPT-5
MedCode (Vals AI)49.6%32.2%GPT-5
MMLU Pro (Artificial Analysis run)87.1%Not measuredOnly GPT-5 measured
SimpleQA Verified50.1%Not measuredOnly GPT-5 measured
GeoBench81.0%Not measuredOnly GPT-5 measured
LMArena Text: science1416Not measuredOnly GPT-5 measured
LMArena Text: medicine and healthcare1413Not measuredOnly GPT-5 measured
LMArena Text: legal and government1431Not measuredOnly GPT-5 measured
LMArena Text: business and finance1400Not measuredOnly GPT-5 measured
Neither model has a result on the other 2 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index26
Web design benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
Design Arena: websites11851229Grok 4.20
Design Arena: UI components11801199Grok 4.20
Design Arena: game dev11851192Grok 4.20
Design Arena: data viz12211217GPT-5
Design Arena: 3D10561193Grok 4.20
Design Arena: all code categories11681221Grok 4.20
Design Arena: SVG11891164GPT-5
Design Arena: ASCII art11401174Grok 4.20
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index51
General benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
SAGE (Vals AI)43.7%38.2%GPT-5
MedScribe (Vals AI)83.7%63.4%GPT-5
Vals Multimodal IndexNot measured39.1%Only Grok 4.20 measured
IFBench73.1%81.2%Grok 4.20
Long context reasoning (AA-LCR)78.2%69.0%GPT-5
DTBench90.7%90.1%GPT-5
LMCA40.0%38.7%GPT-5
Fiction.LiveBench97.2%Not measuredOnly GPT-5 measured
Creative writing (Lech Mazur)86.0%Not measuredOnly GPT-5 measured
CL-benchNot measured22.2%Only Grok 4.20 measured
CL-bench LifeNot measured11.9%Only Grok 4.20 measured
LMArena Text1406Not measuredOnly GPT-5 measured
LMArena Text: instruction following1388Not measuredOnly GPT-5 measured
LMArena Text: creative writing1365Not measuredOnly GPT-5 measured
LMArena Vision1232Not measuredOnly GPT-5 measured
LMArena Text: English1409Not measuredOnly GPT-5 measured
LMArena Text: non-English1397Not measuredOnly GPT-5 measured
LMArena Text: Chinese1422Not measuredOnly GPT-5 measured
LMArena Text: German1416Not measuredOnly GPT-5 measured
LMArena Text: Japanese1409Not measuredOnly GPT-5 measured
LMArena Text: Korean1360Not measuredOnly GPT-5 measured
LMArena Text: French1409Not measuredOnly GPT-5 measured
LMArena Text: Spanish1399Not measuredOnly GPT-5 measured
LMArena Text: Russian1407Not measuredOnly GPT-5 measured
LMArena Text: Polish1431Not measuredOnly GPT-5 measured
LMArena Text: multi-turn1426Not measuredOnly GPT-5 measured
LMArena Text: longer queries1399Not measuredOnly GPT-5 measured
LMArena Text: writing and language1384Not measuredOnly GPT-5 measured
LMArena Text: entertainment and media1379Not measuredOnly GPT-5 measured
LMArena Vision: English1231Not measuredOnly GPT-5 measured
LMArena Vision: Chinese1267Not measuredOnly GPT-5 measured
LMArena Vision: reading text1246Not measuredOnly GPT-5 measured
LMArena Vision: humor1219Not measuredOnly GPT-5 measured
LMArena Vision: captioning1212Not measuredOnly GPT-5 measured
LMArena Vision: recognizing things1263Not measuredOnly GPT-5 measured
LMArena Vision: creative writing1210Not measuredOnly GPT-5 measured
Neither model has a result on the other 10 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5 and Grok 4.20
BenchmarkGPT-5Grok 4.20Leader
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$0.0063Fits in one request
Grok 4.20$0.0025Fits in one request

Grok 4.20 costs less

Repository review

50K input + 3K output tokens

GPT-5$0.092Fits in one request
Grok 4.20$0.070Fits in one request

Grok 4.20 costs less

Agent loop

200K input + 10K output tokens

GPT-5$0.350Fits in one request
Grok 4.20$0.275Fits in one request

Grok 4.20 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 and Grok 4.20
SpecificationOpenAI GPT-5SpaceXAI Grok 4.20
MakerOpenAIxAI
WeightsNo public weights listedNo public weights listed
ReleasedAugust 7, 2025March 31, 2026
Context window400K2M
Input $/Mtok$1.25$1.25
Output $/Mtok$10.00$2.50
Coding index38.833.3
Independent measurements behind it32
Cost per solved task$0.39$0.72
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5 better than Grok 4.20 for coding?

Pick GPT-5 for coding: it scores 38.8 on the Vibe Coding Index against 33.3 for Grok 4.20. Pick Grok 4.20 when output tokens cost 4.0x less, or when the context window is larger, 2M against 400K tokens.

Which is cheaper, GPT-5 or Grok 4.20?

GPT-5 costs $1.25 per million input tokens and $10.00 per million output tokens; Grok 4.20 costs $1.25 and $2.50. Per solved SWE-bench Verified task, GPT-5 costs $0.39 and Grok 4.20 $0.72.

Which has the bigger context window, GPT-5 or Grok 4.20?

Grok 4.20, with 2M tokens against 400K.

How many benchmarks is the GPT-5 vs Grok 4.20 comparison based on?

38 benchmarks have a result for both models as of October 21, 2026. GPT-5's coding index rests on 3 independent benchmarks and Grok 4.20's on 2. Where only one model has a result, the page says so instead of naming a winner.

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