# GPT-5.1-Codex vs GPT-6.1 Sol

> GPT-5.1-Codex has enough public results to be ranked (#178); GPT-6.1 Sol does not yet, so treat this comparison as directional.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-gpt-6-1-sol
- Last updated: 2026-10-10
- Shared benchmarks: 0

## Summary

- The widest gap is in coding, where GPT-6.1 Sol leads 51.4 to 41.7.
- GPT-5.1-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $2 / $10 for GPT-6.1 Sol.
- GPT-6.1 Sol accepts more context: 1.05M tokens versus 400K.

## Snapshot

| | GPT-5.1-Codex | GPT-6.1 Sol |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 38.2 | 42.1 |
| Rank | 178 | — |
| Context | 400K | 1.05M |
| Input $/M | $1.25 | $2 |
| Output $/M | $10 | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.1-Codex: 41.7 (#107)
- GPT-6.1 Sol: 51.4

| Benchmark | GPT-5.1-Codex | GPT-6.1 Sol |
|---|---|---|
| DeepSWE | — | 75.2% |
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 37.8 (#32)
- GPT-6.1 Sol: 34.3

| Benchmark | GPT-5.1-Codex | GPT-6.1 Sol |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| GDP.pdf | — | 32% |
| METR Time Horizons | 70.8% | — |

## Math

- GPT-5.1-Codex: 29.3 (#218)
- GPT-6.1 Sol: —

| Benchmark | GPT-5.1-Codex | GPT-6.1 Sol |
|---|---|---|
| ProofBench | 9% | — |

## FAQ

### Is GPT-5.1-Codex better than GPT-6.1 Sol?

GPT-5.1-Codex has enough public results to be ranked (#178); GPT-6.1 Sol does not yet, so treat this comparison as directional.

### Which is cheaper, GPT-5.1-Codex or GPT-6.1 Sol?

GPT-5.1-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; GPT-6.1 Sol lists at $2 and $10.

### Is GPT-5.1-Codex or GPT-6.1 Sol better for coding?

GPT-6.1 Sol scores higher on coding benchmarks: 51.4 versus 41.7 in the Noometry coding category.

### Which has the bigger context window?

GPT-6.1 Sol does, with 1.05M tokens against 400K.

### How many benchmarks do GPT-5.1-Codex and GPT-6.1 Sol share?

0 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and GPT-6.1 Sol has 2.