GPT-5.1 vs Inkling 2 Small
Inkling 2 Small leads GPT-5.1 on coding, 48.9 to 40.5 on the Vibe Coding Index, and Inkling 2 Small costs 10.0x less per output token ($1.00 vs $10.00 per million). Updated November 14, 2026; 28 benchmarks have a result for both.
GPT-5.1 or Inkling 2 Small: which to pick
Pick Inkling 2 Small for coding: it scores 48.9 on the Vibe Coding Index against 40.5 for GPT-5.1.
Pick GPT-5.1 for work measured by LMArena Text: software and IT or LMArena Text: hard prompts, where it leads.
- Shared results
- 28
- GPT-5.1 only
- 77
- Inkling 2 Small only
- 23
- 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
Inkling 2 Small
Inkling 2 Small scores 48.9 against 40.5.
3 benchmarks behind each score
Intelligence
AA Intelligence Index
No call
Only Inkling 2 Small has a AA Intelligence Index result, 30.6.
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
No call
Only GPT-5.1 has a Design Arena: websites result, 1179.
Directional only
General
Vals Index
No call
Only Inkling 2 Small has a Vals Index result, 56.1%.
Directional only
Long documents
Listed context window
Inkling 2 Small
Inkling 2 Small takes 1.05M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Inkling 2 Small
GPT-5.1 $0.0063, Inkling 2 Small $0.0008 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 40.5 from 3 benchmarks, Inkling 2 Small 48.9 from 3 benchmarks.
- Widest category
- Agentic work, 35.3 points apart on average over 1 shared benchmark.
- Widest single gap
- GDPval-AA: GPT-5.1 834 against Inkling 2 Small 1630, 66.4 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1 $10.00 against Inkling 2 Small $1.00 per million output tokens, 10.0x apart.
- Context window
- GPT-5.1 takes 400K tokens, Inkling 2 Small 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 | Inkling 2 Small | Ties |
|---|---|---|---|---|
| Coding | 1 | 5 | ||
| Agentic work | 0 | 1 | ||
| Reasoning | 2 | 4 | ||
| Math | 0 | 1 | ||
| Knowledge | 2 | 0 | ||
| General | 10 | 2 | ||
| All shared boards | 15 | 13 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index15
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.0% | Not measured | Only GPT-5.1 measured |
| LMArena WebDev | 1397 | 1647 | Inkling 2 Small |
| AA Coding Index | 49.4 | Not measured | Only GPT-5.1 measured |
| 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 | 12.6% | Only Inkling 2 Small measured |
| Vibe Code Bench (Vals AI) | 24.6% | 81.5% | Inkling 2 Small |
| ProgramBench (Vals AI) | Not measured | 0.5% | Only Inkling 2 Small measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 43.1% | Only Inkling 2 Small measured |
| CyberBench (Vals AI) | Not measured | 72.7% | Only Inkling 2 Small measured |
| LiveCodeBench (Artificial Analysis run) | 86.8% | Not measured | Only GPT-5.1 measured |
| SciCode | Not measured | 52.3% | Only Inkling 2 Small measured |
| Terminal-Bench Hard (Artificial Analysis run) | 45.5% | Not measured | Only GPT-5.1 measured |
| Terminal-Bench 4.0 (Artificial Analysis run) | Not measured | 13.1% | Only Inkling 2 Small measured |
| FrontierCode 2.0 | Not measured | 25.4% | Only Inkling 2 Small measured |
| Terminal-Bench | 47.6% | Not measured | Only GPT-5.1 measured |
| GSO-Bench | 13.7% | Not measured | Only GPT-5.1 measured |
| WeirdML | 60.8% | Not measured | Only GPT-5.1 measured |
| LMArena Text: coding | 1453 | 1455 | Inkling 2 Small |
| LMArena Text: software and IT | 1454 | 1443 | GPT-5.1 |
| LMArena WebDev: React | 1307 | 1660 | Inkling 2 Small |
| LMArena WebDev: HTML | 1406 | 1661 | Inkling 2 Small |
| LMArena WebDev: from an image | 1419 | Not measured | Only GPT-5.1 measured |
| SWE-Bench Pro V2 | Not measured | 97.7% | Only Inkling 2 Small measured |
| Terminal-Bench 2.0 | 47.6% | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 27 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| AA Intelligence Index | Not measured | 30.6 | Only Inkling 2 Small measured |
| Epoch Capabilities Index | 150.9 | Not measured | Only GPT-5.1 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| SREBench (Vals AI) | Not measured | 1.9% | Only Inkling 2 Small measured |
| Tax Agent Bench (Vals AI) | Not measured | 38.9% | Only Inkling 2 Small measured |
| Legal Research Bench (Vals AI) | Not measured | 46.6% | Only Inkling 2 Small measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 21.7% | Only Inkling 2 Small measured |
| BioMysteryBench (Vals AI) | Not measured | 70.0% | Only Inkling 2 Small measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 2.9% | Only Inkling 2 Small measured |
| Vals Science Index | Not measured | 32.7% | Only Inkling 2 Small measured |
| τ²-Bench Telecom | 81.9% | Not measured | Only GPT-5.1 measured |
| APEX-Agents | Not measured | 46.8% | Only Inkling 2 Small measured |
| DeepResearch Bench | 42.8% | Not measured | Only GPT-5.1 measured |
| Vending-Bench 2 | $1,473 | Not measured | Only GPT-5.1 measured |
| LMArena Search | 1199 | Not measured | Only GPT-5.1 measured |
| MCP Atlas | 50.1% | 85.4% | Inkling 2 Small |
| Neither model has a result on the other 31 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index24
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| GPQA Diamond | 86.6% | Not measured | Only GPT-5.1 measured |
| MysteryMechanism (Vals AI) | Not measured | 25.2% | Only Inkling 2 Small measured |
| MMMU Pro (Vals AI) | 83.2% | Not measured | Only GPT-5.1 measured |
| GPQA Diamond (Artificial Analysis run) | 87.3% | Not measured | Only GPT-5.1 measured |
| Humanity's Last Exam (Artificial Analysis run) | 28.5% | 44.1% | Inkling 2 Small |
| HLE-Diamond (Artificial Analysis run) | Not measured | 28.7% | Only Inkling 2 Small measured |
| CritPt v2, hard subset (Artificial Analysis run) | Not measured | 35.0% | Only Inkling 2 Small measured |
| GPQA Diamond (Epoch AI run) | 87.6% | Not measured | Only GPT-5.1 measured |
| ARC-AGI | 72.8% | 96.5% | Inkling 2 Small |
| ARC-AGI-2 | 17.6% | 81.7% | Inkling 2 Small |
| SimpleBench | 53.2% | Not measured | Only GPT-5.1 measured |
| Chess puzzles | 42.0% | Not measured | Only GPT-5.1 measured |
| Mystery game puzzles | 19.0% | Not measured | Only GPT-5.1 measured |
| VPCT | 58.7% | Not measured | Only GPT-5.1 measured |
| LMArena Text: hard prompts | 1457 | 1421 | GPT-5.1 |
| LMArena Text: expert | 1469 | 1478 | Inkling 2 Small |
| LMArena Text: hard prompts in English | 1462 | 1424 | GPT-5.1 |
| LMArena Vision: diagrams | 1264 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: homework | 1274 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 7 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| AIME | 93.3% | Not measured | Only GPT-5.1 measured |
| MGSM (Vals AI) | 93.0% | 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% | Not measured | Only GPT-5.1 measured |
| LMArena Text: math | 1447 | Not measured | Only GPT-5.1 measured |
| LMArena Text: mathematical work | 1450 | Not measured | Only GPT-5.1 measured |
| MathArena | 17.0% | 42.4% | Inkling 2 Small |
| Neither model has a result on the other 7 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-5.1 | Inkling 2 Small | 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% | Not measured | Only GPT-5.1 measured |
| MMLU Pro (Artificial Analysis run) | 87.0% | Not measured | Only GPT-5.1 measured |
| AA-Omniscience | Not measured | 16.1 | Only Inkling 2 Small measured |
| SimpleQA Verified | 48.0% | Not measured | Only GPT-5.1 measured |
| LMArena Text: science | 1459 | 1409 | GPT-5.1 |
| LMArena Text: medicine and healthcare | 1457 | Not measured | Only GPT-5.1 measured |
| LMArena Text: legal and government | 1459 | Not measured | Only GPT-5.1 measured |
| LMArena Text: business and finance | 1431 | 1415 | GPT-5.1 |
| PRBench Finance | 48.0% | Not measured | Only GPT-5.1 measured |
| PRBench Legal | 49.3% | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 4 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| Design Arena: websites | 1179 | Not measured | Only GPT-5.1 measured |
| Design Arena: UI components | 1156 | Not measured | Only GPT-5.1 measured |
| Design Arena: game dev | 1168 | Not measured | Only GPT-5.1 measured |
| Design Arena: data viz | 1201 | Not measured | Only GPT-5.1 measured |
| Design Arena: 3D | 1040 | Not measured | Only GPT-5.1 measured |
| Design Arena: all code categories | 1160 | Not measured | Only GPT-5.1 measured |
| Design Arena: SVG | 1138 | Not measured | Only GPT-5.1 measured |
| Design Arena: ASCII art | 1113 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index102
| Benchmark | GPT-5.1 | Inkling 2 Small | Leader |
|---|---|---|---|
| Vals Index | Not measured | 56.1% | Only Inkling 2 Small measured |
| SAGE (Vals AI) | Not measured | 88.6% | Only Inkling 2 Small measured |
| MedScribe (Vals AI) | 88.1% | Not measured | Only GPT-5.1 measured |
| IFBench | 72.9% | Not measured | Only GPT-5.1 measured |
| Long context reasoning (AA-LCR) | 80.0% | 83.3% | Inkling 2 Small |
| GDPval-AA | 834 | 1630 | Inkling 2 Small |
| DTBench | 90.1% | Not measured | Only GPT-5.1 measured |
| LMCA | 43.9% | Not measured | Only GPT-5.1 measured |
| CL-bench | 23.7% | Not measured | Only GPT-5.1 measured |
| CL-bench Life | 17.3% | Not measured | Only GPT-5.1 measured |
| LMArena Text | 1443 | 1403 | GPT-5.1 |
| LMArena Text: instruction following | 1442 | 1408 | GPT-5.1 |
| LMArena Text: creative writing | 1427 | 1348 | GPT-5.1 |
| LMArena Vision | 1249 | Not measured | Only GPT-5.1 measured |
| LMArena Text: English | 1451 | 1418 | GPT-5.1 |
| LMArena Text: non-English | 1431 | 1390 | GPT-5.1 |
| LMArena Text: Chinese | 1495 | Not measured | Only GPT-5.1 measured |
| LMArena Text: German | 1438 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Japanese | 1455 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Korean | 1399 | Not measured | Only GPT-5.1 measured |
| LMArena Text: French | 1450 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Spanish | 1432 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Russian | 1435 | 1377 | GPT-5.1 |
| LMArena Text: Polish | 1440 | Not measured | Only GPT-5.1 measured |
| LMArena Text: multi-turn | 1450 | 1408 | GPT-5.1 |
| LMArena Text: longer queries | 1447 | 1403 | GPT-5.1 |
| LMArena Text: writing and language | 1428 | 1381 | GPT-5.1 |
| LMArena Text: entertainment and media | 1414 | 1359 | GPT-5.1 |
| LMArena Vision: English | 1251 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: Chinese | 1270 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: reading text | 1254 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: humor | 1264 | 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 | Not measured | Only GPT-5.1 measured |
| LMArena Document | 1403 | Not measured | Only GPT-5.1 measured |
| MultiChallenge | 63.4% | Not measured | Only GPT-5.1 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 | Inkling 2 Small | 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
Inkling 2 Small costs less
Repository review
50K input + 3K output tokens
Inkling 2 Small costs less
Agent loop
200K input + 10K output tokens
Inkling 2 Small 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 | Thinking Machines Inkling 2 Small |
|---|---|---|
| Maker | OpenAI | Thinking Machines |
| Weights | No public weights listed | Open weights |
| Released | November 13, 2025 | November 9, 2026 |
| Context window | 400K | 1.05M |
| Input $/Mtok | $1.25 | $0.30 |
| Output $/Mtok | $10.00 | $1.00 |
| Coding index | 40.5 | 48.9 |
| Independent measurements behind it | 3 | 3 |
| Cost per solved task | $1.02 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1 better than Inkling 2 Small for coding?
Pick Inkling 2 Small for coding: it scores 48.9 on the Vibe Coding Index against 40.5 for GPT-5.1. Pick GPT-5.1 for work measured by LMArena Text: software and IT or LMArena Text: hard prompts, where it leads.
Which is cheaper, GPT-5.1 or Inkling 2 Small?
GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; Inkling 2 Small costs $0.30 and $1.00. Cost per solved task is known for GPT-5.1 only.
Which has the bigger context window, GPT-5.1 or Inkling 2 Small?
Inkling 2 Small, with 1.05M tokens against 400K.
How many benchmarks is the GPT-5.1 vs Inkling 2 Small comparison based on?
28 benchmarks have a result for both models as of November 14, 2026. GPT-5.1's coding index rests on 3 independent benchmarks and Inkling 2 Small's on 3. Where only one model has a result, the page says so instead of naming a winner.