# GPT-5.5 Pro vs Grok 4.20

> Side-by-side benchmark comparison for GPT-5.5 Pro and Grok 4.20 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-5-pro-vs-grok-4-20-beta
- Last updated: September 10, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.5 Pro and Grok 4.20 share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Grok 4.20 has the lower published output-token price.
- Grok 4.20 has the larger published context window at 2M.

## Model Snapshot

| Property | GPT-5.5 Pro | Grok 4.20 |
|----------|----------|----------|
| Creator | OpenAI | xAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 2M |
| Independent public score (not head-to-head) | 61.32 | 67.13 |
| Benchmarks Covered | 6 | 23 |
| Pricing (input/output) | $30.00 / $180.00 | $2.00 / $6.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 58.4 (Estimated · #29/152)
- Grok 4.20 public-lane score: 26.7 (Supported · #145/152)

| Benchmark | GPT-5.5 Pro | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| BrowseComp | 90.1% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 47.1% | Coming soon |
| DeepSearchQA | Coming soon | 62.8% | Coming soon |
| Gert Labs | Coming soon | 38.36% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 44.2% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- Grok 4.20 public-lane score: 28.2 (Supported · #141/151)

| Benchmark | GPT-5.5 Pro | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench Pro | Coming soon | 74.2% | Coming soon |
| SWE-bench Verified | Coming soon | 76.7% | Coming soon |
| SWE-bench Pro | Coming soon | 51.8% | Coming soon |
| Vibe Code Bench | Coming soon | 4.06% | Coming soon |
| LiveCodeBench (Vals) | Coming soon | 84.3% | Coming soon |
| SWE-bench (Vals) | Coming soon | 72.2% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- Grok 4.20 public-lane score: 34.6 (#43/48)

| Benchmark | GPT-5.5 Pro | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 75.2% | Coming soon |
| CharXiv | Coming soon | 60.9% | Coming soon |
| ERQA | Coming soon | 54.1% | Coming soon |
| SimpleVQA | Coming soon | 57.4% | Coming soon |
| MedXpertQA (MM) | Coming soon | 65.8% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- Grok 4.20 public-lane score: 34.2 (Unranked · 2 rankable rows)

| Benchmark | GPT-5.5 Pro | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 53.3% | Coming soon |
| ARC-AGI-3 | Coming soon | 0.1% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 58.9 (Estimated · #39/183)
- Grok 4.20 public-lane score: 49.4 (Supported · #85/183)

| Benchmark | GPT-5.5 Pro | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 57.2% | Coming soon | Coming soon |
| HLE w/o tools | 43.1% | 31.6% | GPT-5.5 Pro |
| GPQA-D | Coming soon | 88.5% | Coming soon |
| HealthBench Hard | Coming soon | 20.3% | Coming soon |
| MedXpertQA (Text) | Coming soon | 50.2% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 88.6% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 86.3% | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 70.2 (Unranked · 3 rankable rows)
- Grok 4.20 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | 52.4% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 51.000% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 39.600% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between GPT-5.5 Pro and Grok 4.20?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [GPT-5.5 Pro vs GPT-5.5](/compare/gpt-5-5-vs-gpt-5-5-pro)
- [Grok 4.20 vs GPT-5.5](/compare/gpt-5-5-vs-grok-4-20-beta)
- [GPT-5.5 Pro vs Grok 4.20 Multi-agent](/compare/gpt-5-5-pro-vs-grok-4-20-multi-agent-beta)
- [Grok 4.20 vs Grok 4.20 Multi-agent](/compare/grok-4-20-beta-vs-grok-4-20-multi-agent-beta)

## Explore More

- [GPT-5.5 Pro profile](/models/gpt-5-5-pro)
- [Grok 4.20 profile](/models/grok-4-20-beta)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)