# Grok 4.1 Fast (Reasoning) vs o3

> Side-by-side benchmark comparison for Grok 4.1 Fast (Reasoning) and o3 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/grok-4-1-fast-reasoning-vs-o3
- Last updated: September 4, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Grok 4.1 Fast (Reasoning) and o3.

## Summary

- Grok 4.1 Fast (Reasoning) and o3 do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Grok 4.1 Fast (Reasoning) | o3 |
|----------|----------|----------|
| Creator | xAI | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 2M | 200K |
| Independent public score (not head-to-head) | 58.18 | 49.12 |
| Benchmarks Covered | 1 | 2 |
| Pricing (input/output) | N/A | $2.00 / $8.00 |

## Category Breakdown

### Coding

- Winner: Insufficient shared evidence
- Grok 4.1 Fast (Reasoning) public-lane score: 48.7 (Estimated · #85/183)
- o3 public-lane score: 48.8 (Estimated · #83/183)

| Benchmark | Grok 4.1 Fast (Reasoning) | o3 | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | 1.20% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Grok 4.1 Fast (Reasoning) public-lane score: 53.3 (Unranked · 1 rankable row)
- o3 public-lane score: 63.3 (Unranked · 1 rankable row)

### Reasoning

- Winner: Insufficient shared evidence
- Grok 4.1 Fast (Reasoning) public-lane score: 71.6 (Unranked · 2 rankable rows)
- o3 public-lane score: 73.7 (Unranked · 2 rankable rows)

### Knowledge

- Winner: Insufficient shared evidence
- Grok 4.1 Fast (Reasoning) public-lane score: 51.5 (Estimated · #82/181)
- o3 public-lane score: 50 (Estimated · #91/181)

### Instruction Following

- Winner: Insufficient shared evidence
- Grok 4.1 Fast (Reasoning) public-lane score: 62.8 (#69/120)
- o3 public-lane score: 87.1 (#33/120)

### Mathematics

- Winner: Insufficient shared evidence
- Grok 4.1 Fast (Reasoning) public-lane score: Coming soon
- o3 public-lane score: 37.8 (Unranked · 2 rankable rows)

| Benchmark | Grok 4.1 Fast (Reasoning) | o3 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | Coming soon | 18.685% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 2.083% | Coming soon |

## FAQ

### Can I compare Grok 4.1 Fast (Reasoning) and o3 on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Grok 4.1 Fast (Reasoning) vs Grok 4.1 Fast](/compare/grok-4-1-fast-vs-grok-4-1-fast-reasoning)
- [o3 vs Grok 4.1 Fast](/compare/grok-4-1-fast-vs-o3)
- [Grok 4.1 Fast (Reasoning) vs o3-pro](/compare/grok-4-1-fast-reasoning-vs-o3-pro)
- [o3 vs o3-pro](/compare/o3-vs-o3-pro)

## Explore More

- [Grok 4.1 Fast (Reasoning) profile](/models/grok-4-1-fast-reasoning)
- [o3 profile](/models/o3)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)