# Grok 4 Fast (Reasoning) vs Qwen3.5 Plus

> Side-by-side benchmark comparison for Grok 4 Fast (Reasoning) and Qwen3.5 Plus across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/grok-4-fast-reasoning-vs-qwen3-5-plus
- Last updated: September 4, 2026

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

## Quick Verdict

Evidence is too thin for a benchmark verdict: Grok 4 Fast (Reasoning) and Qwen3.5 Plus 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 Fast (Reasoning) has the larger published context window at 2M.

## Model Snapshot

| Property | Grok 4 Fast (Reasoning) | Qwen3.5 Plus |
|----------|----------|----------|
| Creator | xAI | Alibaba |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 2M | 1M |
| Independent public score (not head-to-head) | 54.56 | 51.63 |
| Benchmarks Covered | 1 | 4 |
| Pricing (input/output) | N/A | $0.40 / $2.40 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: Coming soon
- Qwen3.5 Plus public-lane score: 50.2 (Estimated · #62/151)

| Benchmark | Grok 4 Fast (Reasoning) | Qwen3.5 Plus | Winner |
|-----------|-----------|-----------|--------|
| JobBench | Coming soon | 18.5% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: 43.9 (Estimated · #119/183)
- Qwen3.5 Plus public-lane score: Coming soon

| Benchmark | Grok 4 Fast (Reasoning) | Qwen3.5 Plus | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | 0.00% | 15.74% | Qwen3.5 Plus |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: 51.1 (Unranked · 1 rankable row)
- Qwen3.5 Plus public-lane score: Coming soon

### Reasoning

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: 72.1 (Unranked · 2 rankable rows)
- Qwen3.5 Plus public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: 49.2 (Estimated · #94/181)
- Qwen3.5 Plus public-lane score: Coming soon

### Instruction Following

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: 60 (#70/120)
- Qwen3.5 Plus public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- Grok 4 Fast (Reasoning) public-lane score: Coming soon
- Qwen3.5 Plus public-lane score: 39.5 (Unranked · 2 rankable rows)

| Benchmark | Grok 4 Fast (Reasoning) | Qwen3.5 Plus | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | Coming soon | 21.034% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 2.083% | Coming soon |

## FAQ

### Is there enough evidence to pick between Grok 4 Fast (Reasoning) and Qwen3.5 Plus?

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

- [Grok 4 Fast (Reasoning) vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-grok-4-fast-reasoning)
- [Qwen3.5 Plus vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-qwen3-5-plus)
- [Grok 4 Fast (Reasoning) vs GPT-6 Astra](/compare/gpt-6-astra-vs-grok-4-fast-reasoning)
- [Qwen3.5 Plus vs GPT-6 Astra](/compare/gpt-6-astra-vs-qwen3-5-plus)

## Explore More

- [Grok 4 Fast (Reasoning) profile](/models/grok-4-fast-reasoning)
- [Qwen3.5 Plus profile](/models/qwen3-5-plus)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)