GPT-5.3-Codex vs Grok 4.5
GPT-5.3-Codex leads Grok 4.5 on coding, 60.0 to 58.6 on the Vibe Coding Index, and Grok 4.5 costs 2.3x less per output token ($6.00 vs $14.00 per million). Updated October 22, 2026; 29 benchmarks have a result for both.
GPT-5.3-Codex or Grok 4.5: which to pick
GPT-5.3-Codex and Grok 4.5 are level for coding, 60.0 against 58.6 on the Vibe Coding Index, so price and context decide.
Pick Grok 4.5 for output tokens 2.3x cheaper ($6.00 vs $14.00 per million) and a larger context window (500K against 400K tokens). Pick GPT-5.3-Codex for a lower cost per solved task ($0.59 against $0.62) and work measured by IOI (Vals AI) or WeirdML, where it leads.
- Shared results
- 29
- GPT-5.3-Codex only
- 5
- Grok 4.5 only
- 94
- 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.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Level: 60.0 against 58.6, inside 2 points.
3 and 6 benchmarks behind the scores
Intelligence
AA Intelligence Index
Grok 4.5
Grok 4.5 leads, 38.8 against 32.5.
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 1162.
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
Grok 4.5
GPT-5.3-Codex $0.0088, Grok 4.5 $0.0050 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
GPT-5.3-Codex
GPT-5.3-Codex $0.59, Grok 4.5 $0.62.
Published attempt cost and pass rate
At a glance
- Coding index
- GPT-5.3-Codex 60.0 from 3 benchmarks, Grok 4.5 58.6 from 6 benchmarks.
- Widest category
- Agentic work, 20.4 points apart on average over 6 shared benchmarks.
- Widest single gap
- Design Arena: agents building full-stack apps: GPT-5.3-Codex 983 against Grok 4.5 1249, 33.3 points apart on a 0 to 100 scale.
- Output price
- GPT-5.3-Codex $14.00 against Grok 4.5 $6.00 per million output tokens, 2.3x apart.
- Context window
- GPT-5.3-Codex 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-5.3-Codex | Bars | Grok 4.5 | Ties |
|---|---|---|---|---|
| Coding | 3 | 7 | ||
| Intelligence | 1 | 1 | ||
| Agentic work | 1 | 5 | ||
| Reasoning | 0 | 2 | ||
| Web design | 0 | 8 | ||
| General | 1 | 0 | ||
| All shared boards | 6 | 23 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index37
| Benchmark | GPT-5.3-Codex | Grok 4.5 | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 94.3% | Only Grok 4.5 measured |
| LMArena WebDev | 1407 | 1553 | Grok 4.5 |
| AA Coding Index | Not measured | 72.4 | Only Grok 4.5 measured |
| LiveCodeBench (Vals AI) | 87.3% | 87.3% | Grok 4.5 |
| SWE-bench Verified (Vals AI) | 78.0% | 86.6% | Grok 4.5 |
| Terminal-Bench 4 (Vals AI) | Not measured | 8.6% | Only Grok 4.5 measured |
| Vibe Code Bench (Vals AI) | 61.8% | 69.0% | Grok 4.5 |
| 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) | 53.8% | 40.6% | GPT-5.3-Codex |
| 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 |
| SciCode | Not measured | 55.0% | Only Grok 4.5 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 53.0% | Not measured | Only GPT-5.3-Codex measured |
| Terminal-Bench | 78.4% | Not measured | Only GPT-5.3-Codex measured |
| FrontierCode | Not measured | 42.4% | Only Grok 4.5 measured |
| WeirdML | 79.3% | 46.4% | GPT-5.3-Codex |
| ALE-Bench | 1655.2 | 1309.3 | GPT-5.3-Codex |
| 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 | 1395 | 1556 | Grok 4.5 |
| LMArena WebDev: HTML | 1422 | 1567 | Grok 4.5 |
| LMArena WebDev: from an image | 1443 | 1562 | Grok 4.5 |
| SciCode | Not measured | 6.5% | Only Grok 4.5 measured |
| Neither model has a result on the other 14 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11
| Benchmark | GPT-5.3-Codex | Grok 4.5 | Leader |
|---|---|---|---|
| AA Intelligence Index | 32.5 | 38.8 | Grok 4.5 |
| Epoch Capabilities Index | 157.1 | 154.1 | GPT-5.3-Codex |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index15
| Benchmark | GPT-5.3-Codex | Grok 4.5 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 41.2 | Only Grok 4.5 measured |
| Design Arena: agents building web apps | 1032 | 1218 | Grok 4.5 |
| Design Arena: agents building full-stack apps | 983 | 1249 | Grok 4.5 |
| Design Arena: agents building mobile apps | 1053 | 1220 | Grok 4.5 |
| Design Arena: agents building Android apps | 1084 | 1236 | Grok 4.5 |
| Design Arena: agents building Godot games | 1124 | 1229 | Grok 4.5 |
| 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 | 86.0% | Not measured | Only GPT-5.3-Codex measured |
| APEX-Agents | Not measured | 56.2% | Only Grok 4.5 measured |
| METR time horizons | 74.5% | Not measured | Only GPT-5.3-Codex measured |
| PostTrainBench | Not measured | 23.4% | Only Grok 4.5 measured |
| Vending-Bench 2 | $5,940 | $3,887 | GPT-5.3-Codex |
| LMArena Search | Not measured | 1216 | Only Grok 4.5 measured |
| Neither model has a result on the other 17 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5.3-Codex | 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) | 91.5% | 93.1% | Grok 4.5 |
| Humanity's Last Exam (Artificial Analysis run) | 42.5% | 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 index6 boards, none shared
| Benchmark | GPT-5.3-Codex | Grok 4.5 | Leader |
|---|---|---|---|
| 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 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
| Benchmark | GPT-5.3-Codex | 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 |
| 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 6 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | GPT-5.3-Codex | Grok 4.5 | Leader |
|---|---|---|---|
| Design Arena: websites | 1162 | 1281 | Grok 4.5 |
| Design Arena: UI components | 1134 | 1280 | Grok 4.5 |
| Design Arena: game dev | 1161 | 1264 | Grok 4.5 |
| Design Arena: data viz | 1164 | 1266 | Grok 4.5 |
| Design Arena: 3D | 1007 | 1257 | Grok 4.5 |
| Design Arena: all code categories | 1144 | 1275 | Grok 4.5 |
| Design Arena: SVG | 1129 | 1215 | Grok 4.5 |
| Design Arena: ASCII art | 1152 | 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 index10
| Benchmark | GPT-5.3-Codex | 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 | 75.4% | Not measured | Only GPT-5.3-Codex measured |
| Long context reasoning (AA-LCR) | 83.3% | 79.3% | GPT-5.3-Codex |
| 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-5.3-Codex | 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
Grok 4.5 costs less
Repository review
50K input + 3K output tokens
Grok 4.5 costs less
Agent loop
200K input + 10K output tokens
Grok 4.5 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-5.3-Codex | SpaceXAI Grok 4.5 |
|---|---|---|
| Maker | OpenAI | xAI |
| Weights | No public weights listed | No public weights listed |
| Released | February 24, 2026 | July 8, 2026 |
| Context window | 400K | 500K |
| Input $/Mtok | $1.75 | $2.00 |
| Output $/Mtok | $14.00 | $6.00 |
| Coding index | 60.0 | 58.6 |
| Independent measurements behind it | 3 | 6 |
| Cost per solved task | $0.59 | $0.62 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.3-Codex better than Grok 4.5 for coding?
GPT-5.3-Codex and Grok 4.5 are level for coding, 60.0 against 58.6 on the Vibe Coding Index, so price and context decide. Pick Grok 4.5 for output tokens 2.3x cheaper ($6.00 vs $14.00 per million) and a larger context window (500K against 400K tokens). Pick GPT-5.3-Codex for a lower cost per solved task ($0.59 against $0.62) and work measured by IOI (Vals AI) or WeirdML, where it leads.
Which is cheaper, GPT-5.3-Codex or Grok 4.5?
GPT-5.3-Codex costs $1.75 per million input tokens and $14.00 per million output tokens; Grok 4.5 costs $2.00 and $6.00. Per solved SWE-bench Verified task, GPT-5.3-Codex costs $0.59 and Grok 4.5 $0.62.
Which has the bigger context window, GPT-5.3-Codex or Grok 4.5?
Grok 4.5, with 500K tokens against 400K.
How many benchmarks is the GPT-5.3-Codex vs Grok 4.5 comparison based on?
29 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 4.5's on 6. Where only one model has a result, the page says so instead of naming a winner.