GPT-6 Astra vs Grok 4.20
GPT-6 Astra leads Grok 4.20 on coding, 85.1 to 33.3 on the Vibe Coding Index, and Grok 4.20 costs 20.0x less per output token ($2.50 vs $50.00 per million). Updated October 22, 2026; 33 benchmarks have a result for both.
vs boards won of 33 shared
GPT-6 Astra or Grok 4.20: which to pick
Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 33.3 for Grok 4.20.
Pick Grok 4.20 for output tokens 20.0x cheaper ($2.50 vs $50.00 per million) and a larger context window (2M against 1.05M tokens).
Model AGPT-6 AstraOpenAI85.1/1005 independent benchmarksNo cost per solved taskModel BGrok 4.20xAI33.3/1002 independent benchmarks$0.72 per solved task
- Shared results
- 33
- GPT-6 Astra only
- 88
- Grok 4.20 only
- 22
- 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.
Coding
Vibe Coding Index, six public coding benchmarks
GPT-6 Astra
GPT-6 Astra scores 85.1 against 33.3.
5 and 2 benchmarks behind the scores
Intelligence
AA Intelligence Index
GPT-6 Astra
GPT-6 Astra leads, 52.7 against 25.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only GPT-6 Astra has a AA Agentic Index result, 51.0.
Directional only
Reasoning
GPQA Diamond
No call
Only Grok 4.20 has a GPQA Diamond result, 88.6%.
Directional only
Math
AIME
No call
Only Grok 4.20 has a AIME result, 96.5%.
Directional only
Knowledge
MMLU Pro
No call
Only Grok 4.20 has a MMLU Pro result, 86.3%.
Directional only
Web design
Design Arena: websites
GPT-6 Astra
GPT-6 Astra leads, 1336 against 1229.
Same board, both measured
General
Vals Index
No call
Only GPT-6 Astra has a Vals Index result, 65.0%.
Directional only
Long documents
Listed context window
Grok 4.20
Grok 4.20 takes 2M tokens against 1.05M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Grok 4.20
GPT-6 Astra $0.035, Grok 4.20 $0.0025 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Grok 4.20 has the number, $0.72.
Directional only
At a glance
- Coding index
- GPT-6 Astra 85.1 from 5 benchmarks, Grok 4.20 33.3 from 2 benchmarks.
- Widest category
- Coding, 59.3 points apart on average over 4 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): GPT-6 Astra 89.6% against Grok 4.20 4.1%, 85.5 points apart on a 0 to 100 scale.
- Output price
- GPT-6 Astra $50.00 against Grok 4.20 $2.50 per million output tokens, 20.0x apart.
- Context window
- GPT-6 Astra takes 1.05M 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.
| Category | GPT-6 Astra | Bars | Grok 4.20 | Ties |
|---|---|---|---|---|
| Coding | 4 | 0 | ||
| Intelligence | 2 | 0 | ||
| Agentic work | 9 | 0 | ||
| Reasoning | 4 | 0 | ||
| Knowledge | 1 | 0 | ||
| Web design | 8 | 0 | ||
| General | 5 | 0 | ||
| All shared boards | 33 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index40
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| LiveBench coding | 93.7% | Not measured | Only GPT-6 Astra measured |
| LMArena WebDev | 1774 | Not measured | Only GPT-6 Astra measured |
| AA Coding Index | 76.9 | Not measured | Only GPT-6 Astra measured |
| LiveCodeBench (Vals AI) | Not measured | 84.3% | Only Grok 4.20 measured |
| SWE-bench Verified (Vals AI) | Not measured | 72.2% | Only Grok 4.20 measured |
| Terminal-Bench 4 (Vals AI) | 59.6% | Not measured | Only GPT-6 Astra measured |
| Vibe Code Bench (Vals AI) | 89.6% | 4.1% | GPT-6 Astra |
| Code migration (Vals AI) | 67.7% | 0.3% | GPT-6 Astra |
| ProgramBench (Vals AI) | 5.5% | Not measured | Only GPT-6 Astra measured |
| IOI (Vals AI) | 100.0% | Not measured | Only GPT-6 Astra measured |
| Terminal-Bench 2.1 (Vals AI) | 87.3% | 44.2% | GPT-6 Astra |
| SWE-bench Multimodal (Vals AI) | 43.3% | Not measured | Only GPT-6 Astra measured |
| Vibe Code Bench 1-100 (Vals AI) | 27.6% | Not measured | Only GPT-6 Astra measured |
| CyberBench (Vals AI) | 41.1% | Not measured | Only GPT-6 Astra measured |
| SciCode | 56.5% | Not measured | Only GPT-6 Astra measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 37.9% | Only Grok 4.20 measured |
| Terminal-Bench | Not measured | 57.3% | Only Grok 4.20 measured |
| FrontierCode | 53.3% | Not measured | Only GPT-6 Astra measured |
| FrontierSWE | 65.5% | Not measured | Only GPT-6 Astra measured |
| GSO-Bench | 79.4% | Not measured | Only GPT-6 Astra measured |
| WeirdML | 93.3% | 52.3% | GPT-6 Astra |
| MirrorCode | 46.7% | Not measured | Only GPT-6 Astra measured |
| ALE-Bench | 2951.3 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: coding | 1489 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: software and IT | 1474 | Not measured | Only GPT-6 Astra measured |
| LMArena WebDev: React | 1798 | Not measured | Only GPT-6 Astra measured |
| LMArena WebDev: HTML | 1775 | Not measured | Only GPT-6 Astra measured |
| LMArena WebDev: from an image | 1726 | Not measured | Only GPT-6 Astra measured |
| SciCode | 12.3% | Not measured | Only GPT-6 Astra measured |
| Neither model has a result on the other 10 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| AA Intelligence Index | 52.7 | 25.7 | GPT-6 Astra |
| Epoch Capabilities Index | 168.8 | 152.1 | GPT-6 Astra |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index90
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| AA Agentic Index | 51.0 | Not measured | Only GPT-6 Astra measured |
| Design Arena: agents building web apps | 1373 | 1144 | GPT-6 Astra |
| Design Arena: agents building full-stack apps | 1357 | 1054 | GPT-6 Astra |
| Design Arena: agents building mobile apps | 1312 | 1090 | GPT-6 Astra |
| Design Arena: agents building Android apps | Not measured | 1045 | Only Grok 4.20 measured |
| Design Arena: agents building Godot games | 1348 | 1089 | GPT-6 Astra |
| Design Arena: HTML slides | Not measured | 1180 | Only Grok 4.20 measured |
| Design Arena: PowerPoint slides | 1219 | Not measured | Only GPT-6 Astra measured |
| Design Arena: spreadsheets | 1365 | Not measured | Only GPT-6 Astra measured |
| LiveBench research | 85.2% | Not measured | Only GPT-6 Astra measured |
| LiveBench browser | 84.0% | Not measured | Only GPT-6 Astra measured |
| LiveBench long agentic | 82.4% | Not measured | Only GPT-6 Astra measured |
| SREBench (Vals AI) | 56.9% | Not measured | Only GPT-6 Astra measured |
| Finance Agent (Vals AI) | 53.5% | 28.5% | GPT-6 Astra |
| Tax Agent Bench (Vals AI) | 20.7% | 7.0% | GPT-6 Astra |
| Legal Research Bench (Vals AI) | 39.4% | 13.9% | GPT-6 Astra |
| Harvey's Legal Agent Benchmark (Vals AI) | 7.1% | Not measured | Only GPT-6 Astra measured |
| Excel Modeling Benchmark (Vals AI) | 71.7% | 11.7% | GPT-6 Astra |
| BioMysteryBench (Vals AI) | 79.3% | Not measured | Only GPT-6 Astra measured |
| Terminal-Bench-Science (Vals AI) | 62.9% | Not measured | Only GPT-6 Astra measured |
| Vals Science Index | 65.1% | Not measured | Only GPT-6 Astra measured |
| Time Horizon Index (Vals AI) | 90.5% | Not measured | Only GPT-6 Astra measured |
| CUA-bench (Vals AI) | 19.2% | Not measured | Only GPT-6 Astra measured |
| Robo-bench (Vals AI) | 23.3% | Not measured | Only GPT-6 Astra measured |
| τ²-Bench Telecom | Not measured | 93.0% | Only Grok 4.20 measured |
| APEX-Agents | 64.7% | Not measured | Only GPT-6 Astra measured |
| Remote Labor Index | 20.8% | Not measured | Only GPT-6 Astra measured |
| BALROG | 68.3% | Not measured | Only GPT-6 Astra measured |
| SpireClimb | 25.7% | Not measured | Only GPT-6 Astra measured |
| Vending-Bench 2 | $15,515 | $4,663 | GPT-6 Astra |
| Neither model has a result on the other 11 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 88.6% | Only Grok 4.20 measured |
| LiveBench reasoning | 92.7% | Not measured | Only GPT-6 Astra measured |
| MysteryMechanism (Vals AI) | 53.1% | Not measured | Only GPT-6 Astra measured |
| MMMU Pro (Vals AI) | Not measured | 83.5% | Only Grok 4.20 measured |
| GPQA Diamond (Artificial Analysis run) | 96.3% | 91.1% | GPT-6 Astra |
| Humanity's Last Exam (Artificial Analysis run) | 54.7% | 34.5% | GPT-6 Astra |
| GPQA Diamond (Epoch AI run) | 95.8% | Not measured | Only GPT-6 Astra measured |
| ARC-AGI | 98.5% | 89.5% | GPT-6 Astra |
| ARC-AGI-2 | 95.0% | 65.1% | GPT-6 Astra |
| Chess puzzles | 74.0% | Not measured | Only GPT-6 Astra measured |
| Mystery game puzzles | 84.0% | Not measured | Only GPT-6 Astra measured |
| EBR-bench | 76.2% | Not measured | Only GPT-6 Astra measured |
| LMArena Text: hard prompts | 1463 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: expert | 1489 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: hard prompts in English | 1464 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision: diagrams | 1297 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision: homework | 1337 | Not measured | Only GPT-6 Astra measured |
| Kagi LLM Benchmark | Not measured | 75.0% | Only Grok 4.20 measured |
| Neither model has a result on the other 4 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index7 boards, none shared
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| AIME | Not measured | 96.5% | Only Grok 4.20 measured |
| OTIS Mock AIME | 100.0% | Not measured | Only GPT-6 Astra measured |
| FrontierMath, tiers 1 to 3 | 93.7% | Not measured | Only GPT-6 Astra measured |
| FrontierMath, tier 4 | 97.6% | Not measured | Only GPT-6 Astra measured |
| ProofBench | 99.0% | Not measured | Only GPT-6 Astra measured |
| LMArena Text: math | 1465 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: mathematical work | 1484 | Not measured | Only GPT-6 Astra measured |
| Neither model has a result on the other 6 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 86.3% | Only Grok 4.20 measured |
| LegalBench (Vals AI) | Not measured | 77.7% | Only Grok 4.20 measured |
| CaseLaw (Vals AI) | Not measured | 54.4% | Only Grok 4.20 measured |
| CorpFin (Vals AI) | Not measured | 63.7% | Only Grok 4.20 measured |
| TaxEval (Vals AI) | Not measured | 74.1% | Only Grok 4.20 measured |
| MortgageTax (Vals AI) | Not measured | 45.4% | Only Grok 4.20 measured |
| MedQA (Vals AI) | Not measured | 94.5% | Only Grok 4.20 measured |
| MedCode (Vals AI) | 48.5% | 32.2% | GPT-6 Astra |
| SimpleQA Verified | 75.6% | Not measured | Only GPT-6 Astra measured |
| LMArena Text: science | 1451 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: medicine and healthcare | 1425 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: legal and government | 1462 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: business and finance | 1439 | Not measured | Only GPT-6 Astra measured |
| FACTS Benchmark Suite | 75.7% | Not measured | Only GPT-6 Astra measured |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| Design Arena: websites | 1336 | 1229 | GPT-6 Astra |
| Design Arena: UI components | 1393 | 1200 | GPT-6 Astra |
| Design Arena: game dev | 1478 | 1193 | GPT-6 Astra |
| Design Arena: data viz | 1335 | 1217 | GPT-6 Astra |
| Design Arena: 3D | 1500 | 1193 | GPT-6 Astra |
| Design Arena: all code categories | 1379 | 1221 | GPT-6 Astra |
| Design Arena: SVG | 1431 | 1165 | GPT-6 Astra |
| Design Arena: ASCII art | 1353 | 1175 | GPT-6 Astra |
| LiveBench design | 82.0% | Not measured | Only GPT-6 Astra measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index50
| Benchmark | GPT-6 Astra | Grok 4.20 | Leader |
|---|---|---|---|
| Vals Index | 65.0% | Not measured | Only GPT-6 Astra measured |
| LiveBench data analysis | 83.0% | Not measured | Only GPT-6 Astra measured |
| SAGE (Vals AI) | 46.4% | 38.2% | GPT-6 Astra |
| MedScribe (Vals AI) | 87.9% | 63.4% | GPT-6 Astra |
| Vals Multimodal Index | Not measured | 39.1% | Only Grok 4.20 measured |
| IFBench | Not measured | 81.2% | Only Grok 4.20 measured |
| Long context reasoning (AA-LCR) | 80.7% | 69.0% | GPT-6 Astra |
| DTBench | 97.3% | 90.1% | GPT-6 Astra |
| LMCA | 64.4% | 38.7% | GPT-6 Astra |
| CL-bench | Not measured | 22.2% | Only Grok 4.20 measured |
| Furniture assembly | 80.0% | Not measured | Only GPT-6 Astra measured |
| CL-bench Life | Not measured | 11.9% | Only Grok 4.20 measured |
| LMArena Text | 1441 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: instruction following | 1455 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: creative writing | 1420 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision | 1280 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: English | 1447 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: non-English | 1432 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: Chinese | 1489 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: German | 1459 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: Japanese | 1405 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: Korean | 1428 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: French | 1432 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: Spanish | 1422 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: Russian | 1438 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: Polish | 1422 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: multi-turn | 1447 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: longer queries | 1460 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: writing and language | 1437 | Not measured | Only GPT-6 Astra measured |
| LMArena Text: entertainment and media | 1427 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision: English | 1280 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision: Chinese | 1361 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision: reading text | 1292 | Not measured | Only GPT-6 Astra measured |
| LMArena Vision: creative writing | 1286 | Not measured | Only GPT-6 Astra 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-6 Astra | Grok 4.20 | 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-6 Astra$0.035Fits in one request
Grok 4.20$0.0025Fits in one request
Grok 4.20 costs less
Repository review
50K input + 3K output tokens
GPT-6 Astra$0.650Fits in one request
Grok 4.20$0.070Fits in one request
Grok 4.20 costs less
Agent loop
200K input + 10K output tokens
GPT-6 Astra$2.50Fits 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.
| Specification | OpenAI GPT-6 Astra | SpaceXAI Grok 4.20 |
|---|---|---|
| Maker | OpenAI | xAI |
| Weights | No public weights listed | No public weights listed |
| Released | September 4, 2026 | March 31, 2026 |
| Context window | 1.05M | 2M |
| Input $/Mtok | $10.00 | $1.25 |
| Output $/Mtok | $50.00 | $2.50 |
| Coding index | 85.1 | 33.3 |
| Independent measurements behind it | 5 | 2 |
| Cost per solved task | Not computable | $0.72 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-6 Astra better than Grok 4.20 for coding?
Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 33.3 for Grok 4.20. Pick Grok 4.20 for output tokens 20.0x cheaper ($2.50 vs $50.00 per million) and a larger context window (2M against 1.05M tokens).
Which is cheaper, GPT-6 Astra or Grok 4.20?
GPT-6 Astra costs $10.00 per million input tokens and $50.00 per million output tokens; Grok 4.20 costs $1.25 and $2.50. Cost per solved task is known for Grok 4.20 only.
Which has the bigger context window, GPT-6 Astra or Grok 4.20?
Grok 4.20, with 2M tokens against 1.05M.
How many benchmarks is the GPT-6 Astra vs Grok 4.20 comparison based on?
33 benchmarks have a result for both models as of October 22, 2026. GPT-6 Astra's coding index rests on 5 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.