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GPT-5.1-Codex-Mini vs Llama 3.1 8B Instruct

GPT-5.1-Codex-Mini leads Llama 3.1 8B Instruct on the Artificial Analysis Intelligence Index, 20.4 to 6.9, and Llama 3.1 8B Instruct costs 25.0x less per output token ($0.08 vs $2.00 per million). Updated October 21, 2026; 11 benchmarks have a result for both.

Replace GPT-5.1-Codex-Mini Replace Llama 3.1 8B Instruct
GPT-5.1-Codex-MiniOpenAI
Coding
No data
Overall
20.4
Output $/M
$2.00
11
Llama 3.1 8B InstructMeta Llama
Coding
No data
Overall
6.9
Output $/M
$0.08
0
vs boards won of 11 shared

GPT-5.1-Codex-Mini or Llama 3.1 8B Instruct: which to pick

Neither model has a coding score yet, so the two cannot be ranked on coding.

Pick GPT-5.1-Codex-Mini for a larger context window (400K against 131K tokens).

Model AGPT-5.1-Codex-MiniOpenAINot benchmarked1 independent benchmarkNo cost per solved taskModel BLlama 3.1 8B InstructMeta LlamaNot benchmarkedNo coding benchmarkNo cost per solved task
Shared results
11
GPT-5.1-Codex-Mini only
11
Llama 3.1 8B Instruct only
39
Like-for-like categories
7 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-5.1-Codex-Mini not benchmarked, Llama 3.1 8B Instruct not benchmarked.
Widest category
Math, 87.4 points apart on average over 2 shared benchmarks.
Widest single gap
AA Math Index: GPT-5.1-Codex-Mini 91.7 against Llama 3.1 8B Instruct 4.3, 87.4 points apart on a 0 to 100 scale.
Output price
GPT-5.1-Codex-Mini $2.00 against Llama 3.1 8B Instruct $0.08 per million output tokens, 25.0x apart.
Context window
GPT-5.1-Codex-Mini takes 400K tokens, Llama 3.1 8B Instruct 131K.

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-5.1-Codex-MiniBarsLlama 3.1 8B InstructTies
Coding20
Intelligence10
Agentic work10
Reasoning20
Math20
Knowledge10
General20
All shared boards110
CodingLike-for-likeSix of these boards feed the Vibe Coding Index20
Coding benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
LMArena WebDev1244Not measuredOnly GPT-5.1-Codex-Mini measured
AA Coding IndexNot measured5.4Only Llama 3.1 8B Instruct measured
LiveCodeBench (Artificial Analysis run)83.6%11.6%GPT-5.1-Codex-Mini
Terminal-Bench Hard (Artificial Analysis run)33.3%0.8%GPT-5.1-Codex-Mini
Terminal-Bench61.6%Not measuredOnly GPT-5.1-Codex-Mini measured
WeirdMLNot measured1.7%Only Llama 3.1 8B Instruct measured
LMArena Text: codingNot measured1195Only Llama 3.1 8B Instruct measured
LMArena Text: software and ITNot measured1195Only Llama 3.1 8B Instruct measured
LMArena WebDev: HTML1253Not measuredOnly GPT-5.1-Codex-Mini measured
Neither model has a result on the other 29 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
AA Intelligence Index20.46.9GPT-5.1-Codex-Mini
Epoch Capabilities IndexNot measured116.5Only Llama 3.1 8B Instruct measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
Agentic work benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
τ²-Bench Telecom62.9%16.4%GPT-5.1-Codex-Mini
BALROGNot measured15.1%Only Llama 3.1 8B Instruct measured
Neither model has a result on the other 37 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index20
Reasoning benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
GPQA Diamond (Artificial Analysis run)81.3%25.9%GPT-5.1-Codex-Mini
Humanity's Last Exam (Artificial Analysis run)18.5%5.3%GPT-5.1-Codex-Mini
GPQA Diamond (Epoch AI run)Not measured27.0%Only Llama 3.1 8B Instruct measured
LMArena Text: hard promptsNot measured1175Only Llama 3.1 8B Instruct measured
LMArena Text: expertNot measured1144Only Llama 3.1 8B Instruct measured
LMArena Text: hard prompts in EnglishNot measured1196Only Llama 3.1 8B Instruct measured
Neither model has a result on the other 15 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index20
Math benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
AA Math Index91.74.3GPT-5.1-Codex-Mini
AIME 2025 (Artificial Analysis run)91.7%4.3%GPT-5.1-Codex-Mini
OTIS Mock AIMENot measured1.7%Only Llama 3.1 8B Instruct measured
MATH level 5Not measured22.9%Only Llama 3.1 8B Instruct measured
GSM8KNot measured82.4%Only Llama 3.1 8B Instruct measured
LMArena Text: mathNot measured1179Only Llama 3.1 8B Instruct measured
LMArena Text: mathematical workNot measured1180Only Llama 3.1 8B Instruct measured
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index10
Knowledge benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
MMLU Pro (Artificial Analysis run)82.0%47.6%GPT-5.1-Codex-Mini
MMLUNot measured56.1%Only Llama 3.1 8B Instruct measured
LMArena Text: scienceNot measured1193Only Llama 3.1 8B Instruct measured
LMArena Text: medicine and healthcareNot measured1182Only Llama 3.1 8B Instruct measured
LMArena Text: legal and governmentNot measured1206Only Llama 3.1 8B Instruct measured
LMArena Text: business and financeNot measured1166Only Llama 3.1 8B Instruct measured
Neither model has a result on the other 11 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
Web design benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
Design Arena: websites1111Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: UI components1081Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: game dev1092Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: data viz1097Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: 3D988Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: all code categories1094Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: SVG978Not measuredOnly GPT-5.1-Codex-Mini measured
Design Arena: ASCII art1105Not measuredOnly GPT-5.1-Codex-Mini measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index20
General benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
IFBench67.9%28.6%GPT-5.1-Codex-Mini
Long context reasoning (AA-LCR)66.7%18.0%GPT-5.1-Codex-Mini
DTBenchNot measured50.9%Only Llama 3.1 8B Instruct measured
LMCANot measured5.4%Only Llama 3.1 8B Instruct measured
PIQANot measured81.2%Only Llama 3.1 8B Instruct measured
LMArena TextNot measured1187Only Llama 3.1 8B Instruct measured
LMArena Text: instruction followingNot measured1159Only Llama 3.1 8B Instruct measured
LMArena Text: creative writingNot measured1154Only Llama 3.1 8B Instruct measured
LMArena Text: EnglishNot measured1218Only Llama 3.1 8B Instruct measured
LMArena Text: non-EnglishNot measured1148Only Llama 3.1 8B Instruct measured
LMArena Text: ChineseNot measured1151Only Llama 3.1 8B Instruct measured
LMArena Text: GermanNot measured1144Only Llama 3.1 8B Instruct measured
LMArena Text: JapaneseNot measured1061Only Llama 3.1 8B Instruct measured
LMArena Text: KoreanNot measured1053Only Llama 3.1 8B Instruct measured
LMArena Text: FrenchNot measured1178Only Llama 3.1 8B Instruct measured
LMArena Text: SpanishNot measured1169Only Llama 3.1 8B Instruct measured
LMArena Text: RussianNot measured1158Only Llama 3.1 8B Instruct measured
LMArena Text: multi-turnNot measured1172Only Llama 3.1 8B Instruct measured
LMArena Text: longer queriesNot measured1181Only Llama 3.1 8B Instruct measured
LMArena Text: writing and languageNot measured1162Only Llama 3.1 8B Instruct measured
LMArena Text: entertainment and mediaNot measured1145Only Llama 3.1 8B Instruct measured
Neither model has a result on the other 25 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5.1-Codex-Mini and Llama 3.1 8B Instruct
BenchmarkGPT-5.1-Codex-MiniLlama 3.1 8B InstructLeader
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-5.1-Codex-Mini$0.0013Fits in one request
Llama 3.1 8B Instruct$0.0001Fits in one request

Llama 3.1 8B Instruct costs less

Repository review

50K input + 3K output tokens

GPT-5.1-Codex-Mini$0.018Fits in one request
Llama 3.1 8B Instruct$0.0027Fits in one request

Llama 3.1 8B Instruct costs less

Agent loop

200K input + 10K output tokens

GPT-5.1-Codex-Mini$0.070Fits in one request
Llama 3.1 8B Instruct$0.011Exceeds the context window

Llama 3.1 8B Instruct 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-5.1-Codex-Mini and Llama 3.1 8B Instruct
SpecificationOpenAI GPT-5.1-Codex-MiniMeta Llama 3.1 8B Instruct
MakerOpenAIMeta Llama
WeightsNo public weights listedOpen weights
ReleasedNovember 13, 2025July 23, 2024
Context window400K131K
Input $/Mtok$0.25$0.05
Output $/Mtok$2.00$0.08
Coding indexNot benchmarkedNot benchmarked
Independent measurements behind it10
Cost per solved taskNot computableNot computable
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.1-Codex-Mini better than Llama 3.1 8B Instruct for coding?

Neither model has a coding score yet, so the two cannot be ranked on coding. Pick GPT-5.1-Codex-Mini for a larger context window (400K against 131K tokens).

Which is cheaper, GPT-5.1-Codex-Mini or Llama 3.1 8B Instruct?

GPT-5.1-Codex-Mini costs $0.25 per million input tokens and $2.00 per million output tokens; Llama 3.1 8B Instruct costs $0.05 and $0.08. Cost per solved task is known for neither of them.

Which has the bigger context window, GPT-5.1-Codex-Mini or Llama 3.1 8B Instruct?

GPT-5.1-Codex-Mini, with 400K tokens against 131K.

How many benchmarks is the GPT-5.1-Codex-Mini vs Llama 3.1 8B Instruct comparison based on?

11 benchmarks have a result for both models as of October 21, 2026. GPT-5.1-Codex-Mini's coding index rests on 1 independent benchmark and Llama 3.1 8B Instruct's on 0. Where only one model has a result, the page says so instead of naming a winner.

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