# GPT-5.1-Codex vs Hy4 preview

> Hy4 preview is the stronger model overall, scoring 44.6 to 38.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-hy4-preview
- 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 Hy4 preview in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Hy4 preview leads 54.5 to 29.3.
- The biggest single-benchmark swing is ProofBench: 9% for GPT-5.1-Codex and 75% for Hy4 preview.
- Hy4 preview is cheaper at $0.83 / $2.50 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Hy4 preview accepts more context: 1.05M tokens versus 400K.
- Hy4 preview has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.1-Codex | Hy4 preview |
|---|---|---|
| Provider | OpenAI | Tencent |
| Noometry Index | 38.2 | 44.6 |
| Rank | 178 | 73 |
| Context | 400K | 1.05M |
| Input $/M | $1.25 | $0.83 |
| Output $/M | $10 | $2.50 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.1-Codex: 41.7 (#107)
- Hy4 preview: 51.4 (#36)

| Benchmark | GPT-5.1-Codex | Hy4 preview |
|---|---|---|
| LMArena WebDev | 1337 | 1633 |
| SWE-bench Verified (bash only) | 66% | — |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 37.8 (#32)
- Hy4 preview: —

| Benchmark | GPT-5.1-Codex | Hy4 preview |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |

## Reasoning

- GPT-5.1-Codex: —
- Hy4 preview: 30.6 (#75)

| Benchmark | GPT-5.1-Codex | Hy4 preview |
|---|---|---|
| NYT Connections (extended) | — | 68.2% |

## Math

- GPT-5.1-Codex: 29.3 (#218)
- Hy4 preview: 54.5 (#37)

| Benchmark | GPT-5.1-Codex | Hy4 preview |
|---|---|---|
| ProofBench | 9% | 75% |

## FAQ

### Is GPT-5.1-Codex better than Hy4 preview?

Hy4 preview is the stronger model overall, scoring 44.6 to 38.2 on the Noometry Index.

### Which is cheaper, GPT-5.1-Codex or Hy4 preview?

Hy4 preview is cheaper. It lists at $0.83 per million input tokens and $2.50 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

### Is GPT-5.1-Codex or Hy4 preview better for coding?

Hy4 preview scores higher on coding benchmarks: 51.4 versus 41.7 in the Noometry coding category.

### Which has the bigger context window?

Hy4 preview does, with 1.05M tokens against 400K.

### How many benchmarks do GPT-5.1-Codex and Hy4 preview share?

2 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Hy4 preview has 3.