GPT-5.1-Codex-Mini vs Grok 4.5
Grok 4.5 leads GPT-5.1-Codex-Mini on the Artificial Analysis Intelligence Index, 38.8 to 20.4, and GPT-5.1-Codex-Mini costs 3.0x less per output token ($2.00 vs $6.00 per million). Updated October 22, 2026; 14 benchmarks have a result for both.
vs boards won of 14 shared
GPT-5.1-Codex-Mini or Grok 4.5: which to pick
Only Grok 4.5 has a coding score, 58.6 on the Vibe Coding Index; GPT-5.1-Codex-Mini has none, so the two cannot be ranked on coding.
Pick GPT-5.1-Codex-Mini for output tokens 3.0x cheaper ($2.00 vs $6.00 per million).
Model AGPT-5.1-Codex-MiniOpenAINot benchmarked1 independent benchmarkNo cost per solved taskModel BGrok 4.5xAI58.6/1006 independent benchmarks$0.62 per solved task
- Shared results
- 14
- GPT-5.1-Codex-Mini only
- 8
- Grok 4.5 only
- 109
- Like-for-like categories
- 5 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.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Grok 4.5 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Grok 4.5
Grok 4.5 leads, 38.8 against 20.4.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Grok 4.5 has a AA Agentic Index result, 41.2.
Directional only
Reasoning
GPQA Diamond
No call
Only Grok 4.5 has a GPQA Diamond result, 92.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Grok 4.5 has a MMLU Pro result, 89.2%.
Directional only
Web design
Design Arena: websites
Grok 4.5
Grok 4.5 leads, 1281 against 1111.
Same board, both measured
Long documents
Listed context window
Grok 4.5
Grok 4.5 takes 500K tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5.1-Codex-Mini
GPT-5.1-Codex-Mini $0.0013, Grok 4.5 $0.0050 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Grok 4.5 has the number, $0.62.
Directional only
At a glance
- Coding index
- GPT-5.1-Codex-Mini not benchmarked, Grok 4.5 58.6 from 6 benchmarks.
- Widest category
- Coding, 48.3 points apart on average over 2 shared benchmarks.
- Widest single gap
- LMArena WebDev: HTML: GPT-5.1-Codex-Mini 1253 against Grok 4.5 1567, 52.4 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1-Codex-Mini $2.00 against Grok 4.5 $6.00 per million output tokens, 3.0x apart.
- Context window
- GPT-5.1-Codex-Mini takes 400K tokens, Grok 4.5 500K.
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.
| Category | GPT-5.1-Codex-Mini | Bars | Grok 4.5 | Ties |
|---|---|---|---|---|
| Coding | 0 | 2 | ||
| Intelligence | 0 | 1 | ||
| Reasoning | 0 | 2 | ||
| Web design | 0 | 8 | ||
| General | 0 | 1 | ||
| All shared boards | 0 | 14 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index02
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 94.3% | Only Grok 4.5 measured |
| LMArena WebDev | 1244 | 1553 | Grok 4.5 |
| AA Coding Index | Not measured | 72.4 | Only Grok 4.5 measured |
| LiveCodeBench (Vals AI) | Not measured | 87.3% | Only Grok 4.5 measured |
| SWE-bench Verified (Vals AI) | Not measured | 86.6% | Only Grok 4.5 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 8.6% | Only Grok 4.5 measured |
| Vibe Code Bench (Vals AI) | Not measured | 69.0% | Only Grok 4.5 measured |
| Code migration (Vals AI) | Not measured | 36.6% | Only Grok 4.5 measured |
| ProgramBench (Vals AI) | Not measured | 0.0% | Only Grok 4.5 measured |
| IOI (Vals AI) | Not measured | 40.6% | Only Grok 4.5 measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 67.8% | Only Grok 4.5 measured |
| SkillsBench (Vals AI) | Not measured | 66.0% | Only Grok 4.5 measured |
| CyberBench (Vals AI) | Not measured | 71.0% | Only Grok 4.5 measured |
| LiveCodeBench (Artificial Analysis run) | 83.6% | Not measured | Only GPT-5.1-Codex-Mini measured |
| SciCode | Not measured | 55.0% | Only Grok 4.5 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 33.3% | Not measured | Only GPT-5.1-Codex-Mini measured |
| Terminal-Bench | 61.6% | Not measured | Only GPT-5.1-Codex-Mini measured |
| FrontierCode | Not measured | 42.4% | Only Grok 4.5 measured |
| WeirdML | Not measured | 46.4% | Only Grok 4.5 measured |
| ALE-Bench | Not measured | 1309.3 | Only Grok 4.5 measured |
| LMArena Text: coding | Not measured | 1474 | Only Grok 4.5 measured |
| LMArena Text: software and IT | Not measured | 1471 | Only Grok 4.5 measured |
| LMArena WebDev: React | Not measured | 1556 | Only Grok 4.5 measured |
| LMArena WebDev: HTML | 1253 | 1567 | Grok 4.5 |
| LMArena WebDev: from an image | Not measured | 1562 | Only Grok 4.5 measured |
| SciCode | Not measured | 6.5% | Only Grok 4.5 measured |
| Neither model has a result on the other 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| AA Intelligence Index | 20.4 | 38.8 | Grok 4.5 |
| Epoch Capabilities Index | Not measured | 154.1 | Only Grok 4.5 measured |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index23 boards, none shared
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 41.2 | Only Grok 4.5 measured |
| Design Arena: agents building web apps | Not measured | 1218 | Only Grok 4.5 measured |
| Design Arena: agents building full-stack apps | Not measured | 1249 | Only Grok 4.5 measured |
| Design Arena: agents building mobile apps | Not measured | 1220 | Only Grok 4.5 measured |
| Design Arena: agents building Android apps | Not measured | 1236 | Only Grok 4.5 measured |
| Design Arena: agents building Godot games | Not measured | 1229 | Only Grok 4.5 measured |
| Design Arena: agents building games | Not measured | 1236 | Only Grok 4.5 measured |
| Design Arena: HTML slides | Not measured | 1205 | Only Grok 4.5 measured |
| Design Arena: PowerPoint slides | Not measured | 1230 | Only Grok 4.5 measured |
| LiveBench research | Not measured | 85.9% | Only Grok 4.5 measured |
| LiveBench browser | Not measured | 44.0% | Only Grok 4.5 measured |
| LiveBench long agentic | Not measured | 27.9% | Only Grok 4.5 measured |
| SREBench (Vals AI) | Not measured | 0.8% | Only Grok 4.5 measured |
| Finance Agent (Vals AI) | Not measured | 48.4% | Only Grok 4.5 measured |
| Tax Agent Bench (Vals AI) | Not measured | 24.9% | Only Grok 4.5 measured |
| Legal Research Bench (Vals AI) | Not measured | 38.0% | Only Grok 4.5 measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 52.9% | Only Grok 4.5 measured |
| Time Horizon Index (Vals AI) | Not measured | 6.3% | Only Grok 4.5 measured |
| τ²-Bench Telecom | 62.9% | Not measured | Only GPT-5.1-Codex-Mini measured |
| APEX-Agents | Not measured | 56.2% | Only Grok 4.5 measured |
| PostTrainBench | Not measured | 23.4% | Only Grok 4.5 measured |
| Vending-Bench 2 | Not measured | $3,887 | Only Grok 4.5 measured |
| LMArena Search | Not measured | 1216 | Only Grok 4.5 measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 92.9% | Only Grok 4.5 measured |
| LiveBench reasoning | Not measured | 87.2% | Only Grok 4.5 measured |
| MMMU Pro (Vals AI) | Not measured | 61.8% | Only Grok 4.5 measured |
| GPQA Diamond (Artificial Analysis run) | 81.3% | 93.1% | Grok 4.5 |
| Humanity's Last Exam (Artificial Analysis run) | 18.5% | 42.7% | Grok 4.5 |
| GPQA Diamond (Epoch AI run) | Not measured | 93.4% | Only Grok 4.5 measured |
| ARC-AGI | Not measured | 87.2% | Only Grok 4.5 measured |
| ARC-AGI-2 | Not measured | 52.6% | Only Grok 4.5 measured |
| SimpleBench | Not measured | 70.0% | Only Grok 4.5 measured |
| Chess puzzles | Not measured | 35.0% | Only Grok 4.5 measured |
| LMArena Text: hard prompts | Not measured | 1462 | Only Grok 4.5 measured |
| LMArena Text: expert | Not measured | 1465 | Only Grok 4.5 measured |
| LMArena Text: hard prompts in English | Not measured | 1464 | Only Grok 4.5 measured |
| LMArena Vision: diagrams | Not measured | 1304 | Only Grok 4.5 measured |
| LMArena Vision: homework | Not measured | 1295 | Only Grok 4.5 measured |
| Kagi LLM Benchmark | Not measured | 83.5% | Only Grok 4.5 measured |
| Neither model has a result on the other 6 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| AA Math Index | 91.7 | Not measured | Only GPT-5.1-Codex-Mini measured |
| AIME 2025 (Artificial Analysis run) | 91.7% | Not measured | Only GPT-5.1-Codex-Mini measured |
| OTIS Mock AIME | Not measured | 97.8% | Only Grok 4.5 measured |
| FrontierMath, tiers 1 to 3 | Not measured | 57.2% | Only Grok 4.5 measured |
| FrontierMath, tier 4 | Not measured | 24.4% | Only Grok 4.5 measured |
| ProofBench | Not measured | 31.0% | Only Grok 4.5 measured |
| LMArena Text: math | Not measured | 1460 | Only Grok 4.5 measured |
| LMArena Text: mathematical work | Not measured | 1482 | Only Grok 4.5 measured |
| Neither model has a result on the other 5 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index13 boards, none shared
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 89.2% | Only Grok 4.5 measured |
| LegalBench (Vals AI) | Not measured | 86.0% | Only Grok 4.5 measured |
| CorpFin (Vals AI) | Not measured | 67.4% | Only Grok 4.5 measured |
| TaxEval (Vals AI) | Not measured | 71.7% | Only Grok 4.5 measured |
| MortgageTax (Vals AI) | Not measured | 61.8% | Only Grok 4.5 measured |
| MedCode (Vals AI) | Not measured | 43.3% | Only Grok 4.5 measured |
| MMLU Pro (Artificial Analysis run) | 82.0% | Not measured | Only GPT-5.1-Codex-Mini measured |
| SimpleQA Verified | Not measured | 48.3% | Only Grok 4.5 measured |
| LMArena Text: science | Not measured | 1464 | Only Grok 4.5 measured |
| LMArena Text: medicine and healthcare | Not measured | 1440 | Only Grok 4.5 measured |
| LMArena Text: legal and government | Not measured | 1463 | Only Grok 4.5 measured |
| LMArena Text: business and finance | Not measured | 1441 | Only Grok 4.5 measured |
| FACTS Benchmark Suite | Not measured | 50.2% | Only Grok 4.5 measured |
| Neither model has a result on the other 5 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| Design Arena: websites | 1111 | 1281 | Grok 4.5 |
| Design Arena: UI components | 1078 | 1280 | Grok 4.5 |
| Design Arena: game dev | 1092 | 1264 | Grok 4.5 |
| Design Arena: data viz | 1097 | 1266 | Grok 4.5 |
| Design Arena: 3D | 988 | 1257 | Grok 4.5 |
| Design Arena: all code categories | 1093 | 1275 | Grok 4.5 |
| Design Arena: SVG | 978 | 1215 | Grok 4.5 |
| Design Arena: ASCII art | 1105 | 1256 | Grok 4.5 |
| LiveBench design | Not measured | 78.1% | Only Grok 4.5 measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| LiveBench data analysis | Not measured | 73.0% | Only Grok 4.5 measured |
| SAGE (Vals AI) | Not measured | 35.0% | Only Grok 4.5 measured |
| MedScribe (Vals AI) | Not measured | 86.9% | Only Grok 4.5 measured |
| Vals Multimodal Index | Not measured | 63.4% | Only Grok 4.5 measured |
| IFBench | 67.9% | Not measured | Only GPT-5.1-Codex-Mini measured |
| Long context reasoning (AA-LCR) | 66.7% | 79.3% | Grok 4.5 |
| DTBench | Not measured | 96.5% | Only Grok 4.5 measured |
| LMCA | Not measured | 45.2% | Only Grok 4.5 measured |
| Surface Evolver Bench | Not measured | 74.4% | Only Grok 4.5 measured |
| Furniture assembly | Not measured | 22.5% | Only Grok 4.5 measured |
| LMArena Text | Not measured | 1448 | Only Grok 4.5 measured |
| LMArena Text: instruction following | Not measured | 1445 | Only Grok 4.5 measured |
| LMArena Text: creative writing | Not measured | 1442 | Only Grok 4.5 measured |
| LMArena Vision | Not measured | 1287 | Only Grok 4.5 measured |
| LMArena Text: English | Not measured | 1453 | Only Grok 4.5 measured |
| LMArena Text: non-English | Not measured | 1440 | Only Grok 4.5 measured |
| LMArena Text: Chinese | Not measured | 1495 | Only Grok 4.5 measured |
| LMArena Text: German | Not measured | 1448 | Only Grok 4.5 measured |
| LMArena Text: Japanese | Not measured | 1430 | Only Grok 4.5 measured |
| LMArena Text: Korean | Not measured | 1406 | Only Grok 4.5 measured |
| LMArena Text: French | Not measured | 1457 | Only Grok 4.5 measured |
| LMArena Text: Spanish | Not measured | 1451 | Only Grok 4.5 measured |
| LMArena Text: Russian | Not measured | 1449 | Only Grok 4.5 measured |
| LMArena Text: Polish | Not measured | 1432 | Only Grok 4.5 measured |
| LMArena Text: multi-turn | Not measured | 1456 | Only Grok 4.5 measured |
| LMArena Text: longer queries | Not measured | 1462 | Only Grok 4.5 measured |
| LMArena Text: writing and language | Not measured | 1445 | Only Grok 4.5 measured |
| LMArena Text: entertainment and media | Not measured | 1434 | Only Grok 4.5 measured |
| LMArena Vision: English | Not measured | 1285 | Only Grok 4.5 measured |
| LMArena Vision: Chinese | Not measured | 1345 | Only Grok 4.5 measured |
| LMArena Vision: reading text | Not measured | 1293 | Only Grok 4.5 measured |
| LMArena Vision: humor | Not measured | 1276 | Only Grok 4.5 measured |
| LMArena Vision: creative writing | Not measured | 1293 | Only Grok 4.5 measured |
| LMArena Document | Not measured | 1452 | Only Grok 4.5 measured |
| Neither model has a result on the other 12 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.1-Codex-Mini | Grok 4.5 | Leader |
|---|---|---|---|
| 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
Grok 4.5$0.0050Fits in one request
GPT-5.1-Codex-Mini costs less
Repository review
50K input + 3K output tokens
GPT-5.1-Codex-Mini$0.018Fits in one request
Grok 4.5$0.118Fits in one request
GPT-5.1-Codex-Mini costs less
Agent loop
200K input + 10K output tokens
GPT-5.1-Codex-Mini$0.070Fits in one request
Grok 4.5$0.460Fits in one request
GPT-5.1-Codex-Mini 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.
| Specification | OpenAI GPT-5.1-Codex-Mini | SpaceXAI Grok 4.5 |
|---|---|---|
| Maker | OpenAI | xAI |
| Weights | No public weights listed | No public weights listed |
| Released | November 13, 2025 | July 8, 2026 |
| Context window | 400K | 500K |
| Input $/Mtok | $0.25 | $2.00 |
| Output $/Mtok | $2.00 | $6.00 |
| Coding index | Not benchmarked | 58.6 |
| Independent measurements behind it | 1 | 6 |
| Cost per solved task | Not computable | $0.62 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1-Codex-Mini better than Grok 4.5 for coding?
Only Grok 4.5 has a coding score, 58.6 on the Vibe Coding Index; GPT-5.1-Codex-Mini has none, so the two cannot be ranked on coding. Pick GPT-5.1-Codex-Mini for output tokens 3.0x cheaper ($2.00 vs $6.00 per million).
Which is cheaper, GPT-5.1-Codex-Mini or Grok 4.5?
GPT-5.1-Codex-Mini costs $0.25 per million input tokens and $2.00 per million output tokens; Grok 4.5 costs $2.00 and $6.00. Cost per solved task is known for Grok 4.5 only.
Which has the bigger context window, GPT-5.1-Codex-Mini or Grok 4.5?
Grok 4.5, with 500K tokens against 400K.
How many benchmarks is the GPT-5.1-Codex-Mini vs Grok 4.5 comparison based on?
14 benchmarks have a result for both models as of October 22, 2026. GPT-5.1-Codex-Mini's coding index rests on 1 independent benchmark and Grok 4.5's on 6. Where only one model has a result, the page says so instead of naming a winner.