GPT-5.1 vs GPT-6 Astra
GPT-6 Astra leads GPT-5.1 on coding, 85.1 to 40.4 on the Vibe Coding Index, and GPT-5.1 costs 5.0x less per output token ($10.00 vs $50.00 per million). Updated October 22, 2026; 70 benchmarks have a result for both.
GPT-5.1 or GPT-6 Astra: which to pick
Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 40.4 for GPT-5.1.
Pick GPT-5.1 for output tokens 5.0x cheaper ($10.00 vs $50.00 per million) and work measured by MedCode (Vals AI) or LMArena Text: science, where it leads.
- Shared results
- 70
- GPT-5.1 only
- 31
- GPT-6 Astra only
- 51
- Like-for-like categories
- 8 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 40.4.
3 and 5 benchmarks behind the scores
Intelligence
AA Intelligence Index
GPT-6 Astra
GPT-6 Astra leads, 52.7 against 24.7.
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 GPT-5.1 has a GPQA Diamond result, 86.6%.
Directional only
Math
AIME
No call
Only GPT-5.1 has a AIME result, 93.3%.
Directional only
Knowledge
MMLU Pro
No call
Only GPT-5.1 has a MMLU Pro result, 86.4%.
Directional only
Web design
Design Arena: websites
GPT-6 Astra
GPT-6 Astra leads, 1336 against 1187.
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
GPT-6 Astra
GPT-6 Astra takes 1.05M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5.1
GPT-5.1 $0.0063, GPT-6 Astra $0.035 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.1 has the number, $1.02.
Directional only
At a glance
- Coding index
- GPT-5.1 40.4 from 3 benchmarks, GPT-6 Astra 85.1 from 5 benchmarks.
- Widest category
- Agentic work, 87.8 points apart on average over 1 shared benchmark.
- Widest single gap
- Vending-Bench 2: GPT-5.1 $1,473 against GPT-6 Astra $15,515, 87.8 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1 $10.00 against GPT-6 Astra $50.00 per million output tokens, 5.0x apart.
- Context window
- GPT-5.1 takes 400K tokens, GPT-6 Astra 1.05M.
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 | Bars | GPT-6 Astra | Ties |
|---|---|---|---|---|
| Coding | 0 | 10 | ||
| Intelligence | 0 | 2 | ||
| Agentic work | 0 | 1 | ||
| Reasoning | 0 | 12 | ||
| Math | 0 | 3 | ||
| Knowledge | 3 | 4 | ||
| Web design | 0 | 8 | ||
| General | 10 | 17 | ||
| All shared boards | 13 | 57 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index010
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.0% | Not measured | Only GPT-5.1 measured |
| LiveBench coding | Not measured | 93.7% | Only GPT-6 Astra measured |
| LMArena WebDev | 1396 | 1774 | GPT-6 Astra |
| AA Coding Index | 49.4 | 76.9 | GPT-6 Astra |
| LiveCodeBench (Vals AI) | 86.5% | Not measured | Only GPT-5.1 measured |
| SWE-bench Verified (Vals AI) | 69.8% | Not measured | Only GPT-5.1 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 59.6% | Only GPT-6 Astra measured |
| Vibe Code Bench (Vals AI) | 24.6% | 89.6% | GPT-6 Astra |
| Code migration (Vals AI) | Not measured | 67.7% | Only GPT-6 Astra measured |
| ProgramBench (Vals AI) | Not measured | 5.5% | Only GPT-6 Astra measured |
| IOI (Vals AI) | Not measured | 100.0% | Only GPT-6 Astra measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 87.3% | Only GPT-6 Astra measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 43.3% | Only GPT-6 Astra measured |
| Vibe Code Bench 1-100 (Vals AI) | Not measured | 27.6% | Only GPT-6 Astra measured |
| CyberBench (Vals AI) | Not measured | 41.1% | Only GPT-6 Astra measured |
| LiveCodeBench (Artificial Analysis run) | 86.8% | Not measured | Only GPT-5.1 measured |
| SciCode | Not measured | 56.5% | Only GPT-6 Astra measured |
| Terminal-Bench Hard (Artificial Analysis run) | 45.5% | Not measured | Only GPT-5.1 measured |
| Terminal-Bench | 47.6% | Not measured | Only GPT-5.1 measured |
| FrontierCode | Not measured | 53.3% | Only GPT-6 Astra measured |
| FrontierSWE | Not measured | 65.5% | Only GPT-6 Astra measured |
| GSO-Bench | 13.7% | 79.4% | GPT-6 Astra |
| WeirdML | 60.8% | 93.3% | GPT-6 Astra |
| MirrorCode | Not measured | 46.7% | Only GPT-6 Astra measured |
| ALE-Bench | Not measured | 2951.3 | Only GPT-6 Astra measured |
| LMArena Text: coding | 1453 | 1489 | GPT-6 Astra |
| LMArena Text: software and IT | 1454 | 1474 | GPT-6 Astra |
| LMArena WebDev: React | 1307 | 1798 | GPT-6 Astra |
| LMArena WebDev: HTML | 1405 | 1775 | GPT-6 Astra |
| LMArena WebDev: from an image | 1421 | 1726 | GPT-6 Astra |
| SciCode | Not measured | 12.3% | Only GPT-6 Astra measured |
| Neither model has a result on the other 8 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| AA Intelligence Index | 24.7 | 52.7 | GPT-6 Astra |
| Epoch Capabilities Index | 149.8 | 168.8 | GPT-6 Astra |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 51.0 | Only GPT-6 Astra measured |
| Design Arena: agents building web apps | Not measured | 1373 | Only GPT-6 Astra measured |
| Design Arena: agents building full-stack apps | Not measured | 1357 | Only GPT-6 Astra measured |
| Design Arena: agents building mobile apps | Not measured | 1312 | Only GPT-6 Astra measured |
| Design Arena: agents building Godot games | Not measured | 1348 | Only GPT-6 Astra measured |
| Design Arena: PowerPoint slides | Not measured | 1219 | Only GPT-6 Astra measured |
| Design Arena: spreadsheets | Not measured | 1365 | Only GPT-6 Astra measured |
| LiveBench research | Not measured | 85.2% | Only GPT-6 Astra measured |
| LiveBench browser | Not measured | 84.0% | Only GPT-6 Astra measured |
| LiveBench long agentic | Not measured | 82.4% | Only GPT-6 Astra measured |
| SREBench (Vals AI) | Not measured | 56.9% | Only GPT-6 Astra measured |
| Finance Agent (Vals AI) | Not measured | 53.5% | Only GPT-6 Astra measured |
| Tax Agent Bench (Vals AI) | Not measured | 20.7% | Only GPT-6 Astra measured |
| Legal Research Bench (Vals AI) | Not measured | 39.4% | Only GPT-6 Astra measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 7.1% | Only GPT-6 Astra measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 71.7% | Only GPT-6 Astra measured |
| BioMysteryBench (Vals AI) | Not measured | 79.3% | Only GPT-6 Astra measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 62.9% | Only GPT-6 Astra measured |
| Vals Science Index | Not measured | 65.1% | Only GPT-6 Astra measured |
| Time Horizon Index (Vals AI) | Not measured | 90.5% | Only GPT-6 Astra measured |
| CUA-bench (Vals AI) | Not measured | 19.2% | Only GPT-6 Astra measured |
| Robo-bench (Vals AI) | Not measured | 23.3% | Only GPT-6 Astra measured |
| τ²-Bench Telecom | 81.9% | Not measured | Only GPT-5.1 measured |
| APEX-Agents | Not measured | 64.7% | Only GPT-6 Astra measured |
| Remote Labor Index | Not measured | 20.8% | Only GPT-6 Astra measured |
| BALROG | Not measured | 68.3% | Only GPT-6 Astra measured |
| DeepResearch Bench | 42.8% | Not measured | Only GPT-5.1 measured |
| SpireClimb | Not measured | 25.7% | Only GPT-6 Astra measured |
| Vending-Bench 2 | $1,473 | $15,515 | GPT-6 Astra |
| Neither model has a result on the other 12 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index012
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| GPQA Diamond | 86.6% | Not measured | Only GPT-5.1 measured |
| LiveBench reasoning | Not measured | 92.7% | Only GPT-6 Astra measured |
| MysteryMechanism (Vals AI) | Not measured | 53.1% | Only GPT-6 Astra measured |
| MMMU Pro (Vals AI) | 83.2% | Not measured | Only GPT-5.1 measured |
| GPQA Diamond (Artificial Analysis run) | 87.3% | 96.3% | GPT-6 Astra |
| Humanity's Last Exam (Artificial Analysis run) | 28.5% | 54.7% | GPT-6 Astra |
| GPQA Diamond (Epoch AI run) | 87.6% | 95.8% | GPT-6 Astra |
| ARC-AGI | 72.8% | 98.5% | GPT-6 Astra |
| ARC-AGI-2 | 17.6% | 95.0% | GPT-6 Astra |
| SimpleBench | 53.2% | Not measured | Only GPT-5.1 measured |
| Chess puzzles | 42.0% | 74.0% | GPT-6 Astra |
| Mystery game puzzles | 19.0% | 84.0% | GPT-6 Astra |
| EBR-bench | Not measured | 76.2% | Only GPT-6 Astra measured |
| VPCT | 58.7% | Not measured | Only GPT-5.1 measured |
| LMArena Text: hard prompts | 1457 | 1463 | GPT-6 Astra |
| LMArena Text: expert | 1470 | 1489 | GPT-6 Astra |
| LMArena Text: hard prompts in English | 1462 | 1464 | GPT-6 Astra |
| LMArena Vision: diagrams | 1264 | 1297 | GPT-6 Astra |
| LMArena Vision: homework | 1272 | 1337 | GPT-6 Astra |
| Neither model has a result on the other 3 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index03
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| AIME | 93.3% | Not measured | Only GPT-5.1 measured |
| MGSM (Vals AI) | 93.0% | Not measured | Only GPT-5.1 measured |
| AA Math Index | 94.0 | Not measured | Only GPT-5.1 measured |
| AIME 2025 (Artificial Analysis run) | 94.0% | Not measured | Only GPT-5.1 measured |
| OTIS Mock AIME | 88.6% | 100.0% | GPT-6 Astra |
| FrontierMath, tiers 1 to 3 | Not measured | 93.7% | Only GPT-6 Astra measured |
| FrontierMath, tier 4 | Not measured | 97.6% | Only GPT-6 Astra measured |
| ProofBench | Not measured | 99.0% | Only GPT-6 Astra measured |
| LMArena Text: math | 1446 | 1465 | GPT-6 Astra |
| LMArena Text: mathematical work | 1449 | 1484 | GPT-6 Astra |
| Neither model has a result on the other 3 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index34
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| MMLU Pro | 86.4% | Not measured | Only GPT-5.1 measured |
| LegalBench (Vals AI) | 85.7% | Not measured | Only GPT-5.1 measured |
| CaseLaw (Vals AI) | 73.4% | Not measured | Only GPT-5.1 measured |
| CorpFin (Vals AI) | 63.8% | Not measured | Only GPT-5.1 measured |
| TaxEval (Vals AI) | 74.9% | Not measured | Only GPT-5.1 measured |
| MortgageTax (Vals AI) | 61.4% | Not measured | Only GPT-5.1 measured |
| MedQA (Vals AI) | 96.4% | Not measured | Only GPT-5.1 measured |
| MedCode (Vals AI) | 52.7% | 48.5% | GPT-5.1 |
| MMLU Pro (Artificial Analysis run) | 87.0% | Not measured | Only GPT-5.1 measured |
| SimpleQA Verified | 48.0% | 75.6% | GPT-6 Astra |
| LMArena Text: science | 1459 | 1451 | GPT-5.1 |
| LMArena Text: medicine and healthcare | 1456 | 1425 | GPT-5.1 |
| LMArena Text: legal and government | 1459 | 1462 | GPT-6 Astra |
| LMArena Text: business and finance | 1431 | 1439 | GPT-6 Astra |
| FACTS Benchmark Suite | 45.0% | 75.7% | GPT-6 Astra |
| Neither model has a result on the other 3 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| Design Arena: websites | 1187 | 1336 | GPT-6 Astra |
| Design Arena: UI components | 1163 | 1393 | GPT-6 Astra |
| Design Arena: game dev | 1178 | 1478 | GPT-6 Astra |
| Design Arena: data viz | 1204 | 1335 | GPT-6 Astra |
| Design Arena: 3D | 1060 | 1500 | GPT-6 Astra |
| Design Arena: all code categories | 1170 | 1379 | GPT-6 Astra |
| Design Arena: SVG | 1149 | 1431 | GPT-6 Astra |
| Design Arena: ASCII art | 1119 | 1353 | GPT-6 Astra |
| LiveBench design | Not measured | 82.0% | Only GPT-6 Astra measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index1017
| Benchmark | GPT-5.1 | GPT-6 Astra | Leader |
|---|---|---|---|
| Vals Index | Not measured | 65.0% | Only GPT-6 Astra measured |
| LiveBench data analysis | Not measured | 83.0% | Only GPT-6 Astra measured |
| SAGE (Vals AI) | 43.2% | 46.4% | GPT-6 Astra |
| MedScribe (Vals AI) | 88.1% | 87.9% | GPT-5.1 |
| IFBench | 72.9% | Not measured | Only GPT-5.1 measured |
| Long context reasoning (AA-LCR) | 80.0% | 80.7% | GPT-6 Astra |
| DTBench | 90.1% | 97.3% | GPT-6 Astra |
| LMCA | 43.9% | 64.4% | GPT-6 Astra |
| CL-bench | 23.7% | Not measured | Only GPT-5.1 measured |
| Furniture assembly | Not measured | 80.0% | Only GPT-6 Astra measured |
| CL-bench Life | 17.3% | Not measured | Only GPT-5.1 measured |
| LMArena Text | 1443 | 1441 | GPT-5.1 |
| LMArena Text: instruction following | 1443 | 1455 | GPT-6 Astra |
| LMArena Text: creative writing | 1427 | 1420 | GPT-5.1 |
| LMArena Vision | 1250 | 1280 | GPT-6 Astra |
| LMArena Text: English | 1451 | 1447 | GPT-5.1 |
| LMArena Text: non-English | 1431 | 1432 | GPT-6 Astra |
| LMArena Text: Chinese | 1495 | 1489 | GPT-5.1 |
| LMArena Text: German | 1438 | 1459 | GPT-6 Astra |
| LMArena Text: Japanese | 1453 | 1405 | GPT-5.1 |
| LMArena Text: Korean | 1401 | 1428 | GPT-6 Astra |
| LMArena Text: French | 1450 | 1432 | GPT-5.1 |
| LMArena Text: Spanish | 1433 | 1422 | GPT-5.1 |
| LMArena Text: Russian | 1435 | 1438 | GPT-6 Astra |
| LMArena Text: Polish | 1440 | 1422 | GPT-5.1 |
| LMArena Text: multi-turn | 1450 | 1447 | GPT-5.1 |
| LMArena Text: longer queries | 1448 | 1460 | GPT-6 Astra |
| LMArena Text: writing and language | 1428 | 1437 | GPT-6 Astra |
| LMArena Text: entertainment and media | 1415 | 1427 | GPT-6 Astra |
| LMArena Vision: English | 1252 | 1280 | GPT-6 Astra |
| LMArena Vision: Chinese | 1270 | 1361 | GPT-6 Astra |
| LMArena Vision: reading text | 1255 | 1292 | GPT-6 Astra |
| LMArena Vision: humor | 1263 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: captioning | 1252 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: recognizing things | 1232 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: creative writing | 1266 | 1286 | GPT-6 Astra |
| LMArena Document | 1403 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 9 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.1 | GPT-6 Astra | 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 costs less
Repository review
50K input + 3K output tokens
GPT-5.1 costs less
Agent loop
200K input + 10K output tokens
GPT-5.1 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 | OpenAI GPT-6 Astra |
|---|---|---|
| Maker | OpenAI | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | November 13, 2025 | September 4, 2026 |
| Context window | 400K | 1.05M |
| Input $/Mtok | $1.25 | $10.00 |
| Output $/Mtok | $10.00 | $50.00 |
| Coding index | 40.4 | 85.1 |
| Independent measurements behind it | 3 | 5 |
| Cost per solved task | $1.02 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1 better than GPT-6 Astra for coding?
Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 40.4 for GPT-5.1. Pick GPT-5.1 for output tokens 5.0x cheaper ($10.00 vs $50.00 per million) and work measured by MedCode (Vals AI) or LMArena Text: science, where it leads.
Which is cheaper, GPT-5.1 or GPT-6 Astra?
GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; GPT-6 Astra costs $10.00 and $50.00. Cost per solved task is known for GPT-5.1 only.
Which has the bigger context window, GPT-5.1 or GPT-6 Astra?
GPT-6 Astra, with 1.05M tokens against 400K.
How many benchmarks is the GPT-5.1 vs GPT-6 Astra comparison based on?
70 benchmarks have a result for both models as of October 22, 2026. GPT-5.1's coding index rests on 3 independent benchmarks and GPT-6 Astra's on 5. Where only one model has a result, the page says so instead of naming a winner.