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GPT-4o (2024-05-13) vs GPT-5.1-Codex

GPT-5.1-Codex leads GPT-4o (2024-05-13) on the Artificial Analysis Intelligence Index, 23.7 to 7.3, and GPT-5.1-Codex costs 1.5x less per output token ($10.00 vs $15.00 per million). Updated October 22, 2026; 5 benchmarks have a result for both.

Replace GPT-4o (2024-05-13) Replace GPT-5.1-Codex
GPT-4o (2024-05-13)OpenAI
Coding
No data
Overall
27.1
Output $/M
$15.00
0
GPT-5.1-CodexOpenAI
Coding
15.3
Overall
No data
Output $/M
$10.00
5
vs boards won of 5 shared

GPT-4o (2024-05-13) or GPT-5.1-Codex: which to pick

Only GPT-5.1-Codex has a coding score, 15.3 on the Vibe Coding Index; GPT-4o (2024-05-13) has none, so the two cannot be ranked on coding.

Compare them on price, context and the boards below.

Model AGPT-4o (2024-05-13)OpenAINot benchmarkedNo coding benchmarkNo cost per solved taskModel BGPT-5.1-CodexOpenAI15.3/1002 independent benchmarks$0.892 per solved task
Shared results
5
GPT-4o (2024-05-13) only
39
GPT-5.1-Codex only
21
Like-for-like categories
4 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-4o (2024-05-13) not benchmarked, GPT-5.1-Codex 15.3 from 2 benchmarks.
Widest category
Coding, 51.5 points apart on average over 1 shared benchmark.
Widest single gap
LiveCodeBench (Artificial Analysis run): GPT-4o (2024-05-13) 33.4% against GPT-5.1-Codex 84.9%, 51.5 points apart on a 0 to 100 scale.
Output price
GPT-4o (2024-05-13) $15.00 against GPT-5.1-Codex $10.00 per million output tokens, 1.5x apart.
Context window
GPT-4o (2024-05-13) takes 128K tokens, GPT-5.1-Codex 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
CategoryGPT-4o (2024-05-13)BarsGPT-5.1-CodexTies
Coding01
Intelligence01
Reasoning02
Knowledge01
All shared boards05
CodingLike-for-likeSix of these boards feed the Vibe Coding Index01
Coding benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
SWE-bench VerifiedNot measured66.0%Only GPT-5.1-Codex measured
LMArena WebDevNot measured1337Only GPT-5.1-Codex measured
AA Coding Index24.2Not measuredOnly GPT-4o (2024-05-13) measured
LiveCodeBench (Vals AI)Not measured85.5%Only GPT-5.1-Codex measured
Vibe Code Bench (Vals AI)Not measured13.1%Only GPT-5.1-Codex measured
LiveCodeBench (Artificial Analysis run)33.4%84.9%GPT-5.1-Codex
Terminal-Bench Hard (Artificial Analysis run)Not measured34.8%Only GPT-5.1-Codex measured
Terminal-BenchNot measured57.8%Only GPT-5.1-Codex measured
ALE-BenchNot measured1244.9Only GPT-5.1-Codex measured
LMArena Text: coding1297Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: software and IT1297Not measuredOnly GPT-4o (2024-05-13) measured
LMArena WebDev: HTMLNot measured1346Only GPT-5.1-Codex measured
Neither model has a result on the other 27 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
Intelligence benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
AA Intelligence Index7.323.7GPT-5.1-Codex
Neither model has a result on the other 1 board here
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
Agentic work benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
Design Arena: agents building web appsNot measured1018Only GPT-5.1-Codex measured
Design Arena: agents building full-stack appsNot measured1086Only GPT-5.1-Codex measured
Design Arena: agents building mobile appsNot measured1191Only GPT-5.1-Codex measured
τ²-Bench TelecomNot measured83.0%Only GPT-5.1-Codex measured
METR time horizons40.8%Not measuredOnly GPT-4o (2024-05-13) measured
BALROG32.3%Not measuredOnly GPT-4o (2024-05-13) measured
Neither model has a result on the other 35 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index02
Reasoning benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
GPQA Diamond50.2%Not measuredOnly GPT-4o (2024-05-13) measured
GPQA Diamond (Artificial Analysis run)52.6%86.0%GPT-5.1-Codex
Humanity's Last Exam (Artificial Analysis run)1.8%25.7%GPT-5.1-Codex
GPQA Diamond (Epoch AI run)48.9%Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: hard prompts1281Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: expert1250Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: hard prompts in English1293Not measuredOnly GPT-4o (2024-05-13) measured
Neither model has a result on the other 15 boards here
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
Math benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
AA Math IndexNot measured95.7Only GPT-5.1-Codex measured
AIME 2025 (Artificial Analysis run)Not measured95.7%Only GPT-5.1-Codex measured
OTIS Mock AIME6.3%Not measuredOnly GPT-4o (2024-05-13) measured
MATH level 551.0%Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: math1284Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: mathematical work1284Not measuredOnly GPT-4o (2024-05-13) measured
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index01
Knowledge benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
MMLU Pro (Artificial Analysis run)74.0%86.0%GPT-5.1-Codex
MMLU84.2%Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: science1295Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: medicine and healthcare1278Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: legal and government1314Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: business and finance1262Not measuredOnly GPT-4o (2024-05-13) measured
Neither model has a result on the other 12 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index5 boards, none shared
Web design benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
Design Arena: websitesNot measured1161Only GPT-5.1-Codex measured
Design Arena: UI componentsNot measured1235Only GPT-5.1-Codex measured
Design Arena: game devNot measured1137Only GPT-5.1-Codex measured
Design Arena: data vizNot measured1213Only GPT-5.1-Codex measured
Design Arena: all code categoriesNot measured1152Only GPT-5.1-Codex measured
Neither model has a result on the other 4 boards here
GeneralDirectional onlyPublic boards, shown as published, kept out of the index22 boards, none shared
General benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
IFBenchNot measured70.0%Only GPT-5.1-Codex measured
Long context reasoning (AA-LCR)Not measured69.3%Only GPT-5.1-Codex measured
LMArena Text1300Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: instruction following1278Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: creative writing1291Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Vision1137Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: English1312Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: non-English1283Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: Chinese1277Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: German1283Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: Japanese1257Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: Korean1234Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: French1304Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: Spanish1292Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: Russian1285Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: Polish1365Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: multi-turn1302Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: longer queries1288Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: writing and language1298Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Text: entertainment and media1289Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Vision: English1147Not measuredOnly GPT-4o (2024-05-13) measured
LMArena Vision: Chinese1132Not measuredOnly GPT-4o (2024-05-13) measured
Neither model has a result on the other 24 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-4o (2024-05-13) and GPT-5.1-Codex
BenchmarkGPT-4o (2024-05-13)GPT-5.1-CodexLeader
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-4o (2024-05-13)$0.013Fits in one request
GPT-5.1-Codex$0.0063Fits in one request

GPT-5.1-Codex costs less

Repository review

50K input + 3K output tokens

GPT-4o (2024-05-13)$0.295Fits in one request
GPT-5.1-Codex$0.092Fits in one request

GPT-5.1-Codex costs less

Agent loop

200K input + 10K output tokens

GPT-4o (2024-05-13)$1.15Exceeds the context window
GPT-5.1-Codex$0.350Fits in one request

GPT-5.1-Codex 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-4o (2024-05-13) and GPT-5.1-Codex
SpecificationOpenAI GPT-4o (2024-05-13)OpenAI GPT-5.1-Codex
MakerOpenAIOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 13, 2024November 13, 2025
Context window128K400K
Input $/Mtok$5.00$1.25
Output $/Mtok$15.00$10.00
Coding indexNot benchmarked15.3
Independent measurements behind it02
Cost per solved taskNot computable$0.892
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-4o (2024-05-13) better than GPT-5.1-Codex for coding?

Only GPT-5.1-Codex has a coding score, 15.3 on the Vibe Coding Index; GPT-4o (2024-05-13) has none, so the two cannot be ranked on coding. Compare them on price, context and the boards below.

Which is cheaper, GPT-4o (2024-05-13) or GPT-5.1-Codex?

GPT-4o (2024-05-13) costs $5.00 per million input tokens and $15.00 per million output tokens; GPT-5.1-Codex costs $1.25 and $10.00. Cost per solved task is known for GPT-5.1-Codex only.

Which has the bigger context window, GPT-4o (2024-05-13) or GPT-5.1-Codex?

GPT-5.1-Codex, with 400K tokens against 128K.

How many benchmarks is the GPT-4o (2024-05-13) vs GPT-5.1-Codex comparison based on?

5 benchmarks have a result for both models as of October 22, 2026. GPT-4o (2024-05-13)'s coding index rests on 0 independent benchmarks and GPT-5.1-Codex's on 2. Where only one model has a result, the page says so instead of naming a winner.

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