# GPT-5.1-Codex vs Inkling-Small

> Inkling-Small is the stronger model overall, scoring 46.5 to 38.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-inkling-small
- Last updated: 2026-10-10
- Shared benchmarks: 2

## Summary

- They share 2 benchmarks with published results for both. GPT-5.1-Codex scores higher in 0 categories and Inkling-Small in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Inkling-Small leads 44.9 to 29.3.
- Inkling-Small is cheaper at $0.45 / $1.20 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Inkling-Small accepts more context: 524K tokens versus 400K.
- Inkling-Small has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| Provider | OpenAI | Thinking Machines Lab |
| Noometry Index | 38.2 | 46.5 |
| Rank | 178 | 57 |
| Context | 400K | 524K |
| Input $/M | $1.25 | $0.45 |
| Output $/M | $10 | $1.20 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.1-Codex: 41.7 (#107)
- Inkling-Small: 43.3 (#80)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| LMArena WebDev | 1337 | 1408 |
| SWE-bench Verified (bash only) | 66% | — |
| SciCode | — | 48.7% |
| LMArena Coding | — | 1451 |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 37.8 (#32)
- Inkling-Small: —

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |

## Reasoning

- GPT-5.1-Codex: —
- Inkling-Small: 39.0 (#53)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| ARC-AGI-2 | — | 40.1% |
| ARC-AGI-1 | — | 84% |
| CritPt | — | 8.3% |
| Chess Puzzles | — | 18% |
| LMArena Hard Prompts | — | 1424 |
| Mystery Game Puzzles | — | 6% |
| Epoch Capabilities Index | — | 150.13 |

## Math

- GPT-5.1-Codex: 29.3 (#218)
- Inkling-Small: 44.9 (#65)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| ProofBench | 9% | 6% |
| FrontierMath (Tiers 1-3) | — | 46.3% |
| FrontierMath Tier 4 | — | 17.1% |
| OTIS Mock AIME 2024-2025 | — | 90% |
| LMArena Math | — | 1453 |

## Knowledge

- GPT-5.1-Codex: —
- Inkling-Small: 48.3 (#71)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| GPQA Diamond | — | 88.5% |
| SimpleQA Verified | — | 19.1% |
| LMArena Expert | — | 1442 |

## Multimodal

- GPT-5.1-Codex: —
- Inkling-Small: 38.4 (#59)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| LMArena Vision | — | 1235 |

## Multilingual

- GPT-5.1-Codex: —
- Inkling-Small: 51.7 (#102)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| LMArena Non-English | — | 1400 |
| LMArena Chinese | — | 1458 |
| LMArena French | — | 1438 |
| LMArena German | — | 1412 |
| LMArena Japanese | — | 1399 |
| LMArena Korean | — | 1355 |
| LMArena Russian | — | 1392 |
| LMArena Spanish | — | 1426 |

## Instruction Following

- GPT-5.1-Codex: —
- Inkling-Small: 73.9 (#112)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| LMArena Instruction Following | — | 1397 |

## Long Context

- GPT-5.1-Codex: —
- Inkling-Small: 42.7 (#113)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| LMArena Longer Query | — | 1401 |

## Writing & Preference

- GPT-5.1-Codex: —
- Inkling-Small: 59.8 (#102)

| Benchmark | GPT-5.1-Codex | Inkling-Small |
|---|---|---|
| LMArena Text | — | 1413 |
| LMArena Creative Writing | — | 1330 |
| EQ-Bench Creative Writing | — | 1491 |
| LMArena Multi-Turn | — | 1420 |

## FAQ

### Is GPT-5.1-Codex better than Inkling-Small?

Inkling-Small is the stronger model overall, scoring 46.5 to 38.2 on the Noometry Index.

### Which is cheaper, GPT-5.1-Codex or Inkling-Small?

Inkling-Small is cheaper. It lists at $0.45 per million input tokens and $1.20 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

### Is GPT-5.1-Codex or Inkling-Small better for coding?

Inkling-Small scores higher on coding benchmarks: 43.3 versus 41.7 in the Noometry coding category.

### Which has the bigger context window?

Inkling-Small does, with 524K tokens against 400K.

### How many benchmarks do GPT-5.1-Codex and Inkling-Small share?

2 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Inkling-Small has 33.