# GPT-5.1-Codex vs Grok 4.20 Multi-Agent

> Grok 4.20 Multi-Agent is the stronger model overall, scoring 46.2 to 38.6 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-grok-4-20-multi-agent
- Last updated: 2026-10-10
- Shared benchmarks: 0

## Summary

- The widest gap is in math, where Grok 4.20 Multi-Agent leads 39.4 to 30.3.
- Grok 4.20 Multi-Agent is cheaper at $1.25 / $2.50 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Grok 4.20 Multi-Agent accepts more context: 1M tokens versus 400K.

## Snapshot

| | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 38.6 | 46.2 |
| Rank | 186 | 65 |
| Context | 400K | 1M |
| Input $/M | $1.25 | $1.25 |
| Output $/M | $10 | $2.50 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.1-Codex: 41.9 (#116)
- Grok 4.20 Multi-Agent: 43.0 (#92)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
| LMArena Coding | — | 1457 |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 38.0 (#33)
- Grok 4.20 Multi-Agent: —

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| LMArena Search | — | 1204 |
| METR Time Horizons | 70.8% | — |

## Reasoning

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 43.9 (#48)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| NYT Connections (extended) | — | 89.6% |
| LMArena Hard Prompts | — | 1448 |

## Math

- GPT-5.1-Codex: 30.3 (#235)
- Grok 4.20 Multi-Agent: 39.4 (#104)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| ProofBench | 9% | — |
| LMArena Math | — | 1442 |

## Knowledge

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 40.4 (#119)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Expert | — | 1445 |

## Multimodal

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 40.5 (#48)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Vision | — | 1259 |

## Multilingual

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 54.4 (#43)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Non-English | — | 1440 |
| LMArena Chinese | — | 1475 |
| LMArena French | — | 1466 |
| LMArena German | — | 1456 |
| LMArena Japanese | — | 1405 |
| LMArena Korean | — | 1416 |
| LMArena Russian | — | 1457 |
| LMArena Spanish | — | 1447 |

## Instruction Following

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 74.8 (#84)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Instruction Following | — | 1420 |

## Long Context

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 43.7 (#88)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Longer Query | — | 1431 |

## Writing & Preference

- GPT-5.1-Codex: —
- Grok 4.20 Multi-Agent: 64.0 (#59)

| Benchmark | GPT-5.1-Codex | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Text | — | 1450 |
| LMArena Creative Writing | — | 1436 |
| LMArena Multi-Turn | — | 1452 |

## FAQ

### Is GPT-5.1-Codex better than Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent is the stronger model overall, scoring 46.2 to 38.6 on the Noometry Index.

### Which is cheaper, GPT-5.1-Codex or Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent is cheaper. It lists at $1.25 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 Grok 4.20 Multi-Agent better for coding?

Grok 4.20 Multi-Agent scores higher on coding benchmarks: 43.0 versus 41.9 in the Noometry coding category.

### Which has the bigger context window?

Grok 4.20 Multi-Agent does, with 1M tokens against 400K.

### How many benchmarks do GPT-5.1-Codex and Grok 4.20 Multi-Agent share?

0 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Grok 4.20 Multi-Agent has 20.