# Grok 4.1 Fast vs Kimi K2.5 (Reasoning)

> Side-by-side benchmark comparison for Grok 4.1 Fast and Kimi K2.5 (Reasoning) across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/grok-4-1-fast-vs-kimi-k2-5-reasoning
- Last updated: October 17, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Evidence is too thin for a benchmark verdict: Grok 4.1 Fast and Kimi K2.5 (Reasoning) 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 4.1 Fast has the lower published output-token price.
- Grok 4.1 Fast has the larger published context window at 1M.

## Model Snapshot

| Property | Grok 4.1 Fast | Kimi K2.5 (Reasoning) |
|----------|----------|----------|
| Creator | xAI | Moonshot AI |
| Type | Proprietary | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 1M | 128K |
| Independent public score (not head-to-head) | 36.45 | 56.09 |
| Benchmarks Covered | 1 | 15 |
| Pricing (input/output) | $0.20 / $0.50 | $0.60 / $3.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: Coming soon
- Kimi K2.5 (Reasoning) public-lane score: 38.3 (Estimated · #71/128)

| Benchmark | Grok 4.1 Fast | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | 47.32% | 32.58% | Grok 4.1 Fast |
| Terminal-Bench 2.0 | Coming soon | 50.8% | Coming soon |
| BrowseComp | Coming soon | 60.6% | Coming soon |
| OSWorld-Verified | Coming soon | 63.3% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: Coming soon
- Kimi K2.5 (Reasoning) public-lane score: Coming soon

| Benchmark | Grok 4.1 Fast | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | Coming soon | 76.8% | Coming soon |
| LiveCodeBench v6 | Coming soon | 85.0% | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 50.8% | Coming soon |
| Vibe Code Bench | Coming soon | 17.54% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: 47.4 (Unranked · 2 rankable rows)
- Kimi K2.5 (Reasoning) public-lane score: 67.1 (Unranked · 1 rankable row)

| Benchmark | Grok 4.1 Fast | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | Coming soon | 61% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: 35.9 (Unranked · 1 rankable row)
- Kimi K2.5 (Reasoning) public-lane score: 69 (#33/54)

| Benchmark | Grok 4.1 Fast | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 78.5% | Coming soon |
| CharXiv | Coming soon | 77.5% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: 31.5 (Estimated · #149/184)
- Kimi K2.5 (Reasoning) public-lane score: 48.8 (Estimated · #85/184)

| Benchmark | Grok 4.1 Fast | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| GPQA | Coming soon | 87.6% | Coming soon |
| MMLU-Pro | Coming soon | 87.1% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: 41.9 (#114/148)
- Kimi K2.5 (Reasoning) public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- Grok 4.1 Fast public-lane score: Coming soon
- Kimi K2.5 (Reasoning) public-lane score: Coming soon

| Benchmark | Grok 4.1 Fast | Kimi K2.5 (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| AIME 2025 | Coming soon | 96.1% | Coming soon |
| HMMT Feb 2025 | Coming soon | 95.4% | Coming soon |

## FAQ

### Is there enough evidence to pick between Grok 4.1 Fast and Kimi K2.5 (Reasoning)?

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 4.1 Fast vs Grok 4.1 Fast (Reasoning)](/compare/grok-4-1-fast-vs-grok-4-1-fast-reasoning)
- [Kimi K2.5 (Reasoning) vs Grok 4.1 Fast (Reasoning)](/compare/grok-4-1-fast-reasoning-vs-kimi-k2-5-reasoning)
- [Grok 4.1 Fast vs Kimi K2.5](/compare/grok-4-1-fast-vs-kimi-k2-5)
- [Kimi K2.5 (Reasoning) vs Kimi K2.5](/compare/kimi-k2-5-vs-kimi-k2-5-reasoning)

## Explore More

- [Grok 4.1 Fast profile](/models/grok-4-1-fast)
- [Kimi K2.5 (Reasoning) profile](/models/kimi-k2-5-reasoning)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)