# GPT-5.5 Pro vs Grok 4.20 Multi-Agent

> GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 45.5 on the Noometry Index. Grok 4.20 Multi-Agent costs 43× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

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

## Summary

- The widest gap is in math, where GPT-5.5 Pro leads 83.8 to 36.6.
- Grok 4.20 Multi-Agent is cheaper at $1.25 / $2.50 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 1M.

## Snapshot

| | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 64.3 | 45.5 |
| Rank | 7 | 62 |
| Context | 1.05M | 1M |
| Input $/M | $30 | $1.25 |
| Output $/M | $180 | $2.50 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: 42.4 (#91)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Coding | — | 1458 |

## Agentic & Tool Use

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: —

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Search | — | 1204 |

## Reasoning

- GPT-5.5 Pro: 73.6 (#7)
- Grok 4.20 Multi-Agent: 42.4 (#44)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| ARC-AGI-2 | 84.6% | — |
| SimpleBench | 76.9% | — |
| NYT Connections (extended) | — | 89.6% |
| ARC-AGI-1 | 96.5% | — |
| CritPt | 30.6% | — |
| Chess Puzzles | 64% | — |
| LMArena Hard Prompts | — | 1448 |
| DTBench | 96% | — |
| LMCA | 53.9% | — |
| Epoch Capabilities Index | 162.45 | — |

## Math

- GPT-5.5 Pro: 83.8 (#8)
- Grok 4.20 Multi-Agent: 36.6 (#106)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87.7% | — |
| FrontierMath Tier 4 | 78% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| LMArena Math | — | 1441 |
| FrontierMath (Feb 2025 set) | 52.4% | — |
| FrontierMath Tier 4 (v1) | 39.6% | — |

## Knowledge

- GPT-5.5 Pro: 64.2 (#17)
- Grok 4.20 Multi-Agent: 39.7 (#116)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| GPQA Diamond | 93.9% | — |
| LMArena Expert | — | 1445 |

## Multimodal

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: 39.8 (#44)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Vision | — | 1259 |

## Multilingual

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: 54.6 (#40)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Non-English | — | 1440 |
| LMArena Chinese | — | 1475 |
| LMArena French | — | 1467 |
| LMArena German | — | 1456 |
| LMArena Japanese | — | 1405 |
| LMArena Korean | — | 1416 |
| LMArena Russian | — | 1457 |
| LMArena Spanish | — | 1447 |

## Instruction Following

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: 75.0 (#80)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Instruction Following | — | 1420 |

## Long Context

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: 43.7 (#84)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Longer Query | — | 1430 |

## Writing & Preference

- GPT-5.5 Pro: —
- Grok 4.20 Multi-Agent: 64.1 (#57)

| Benchmark | GPT-5.5 Pro | Grok 4.20 Multi-Agent |
|---|---|---|
| LMArena Text | — | 1450 |
| LMArena Creative Writing | — | 1435 |
| LMArena Multi-Turn | — | 1451 |

## FAQ

### Is GPT-5.5 Pro better than Grok 4.20 Multi-Agent?

GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 45.5 on the Noometry Index. Grok 4.20 Multi-Agent costs 43× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

### Which is cheaper, GPT-5.5 Pro 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-5.5 Pro lists at $30 and $180.

### Which has the bigger context window?

GPT-5.5 Pro does, with 1.05M tokens against 1M.

### How many benchmarks do GPT-5.5 Pro and Grok 4.20 Multi-Agent share?

0 benchmarks have published results for both models. GPT-5.5 Pro has 14 scored results on Noometry and Grok 4.20 Multi-Agent has 20.