# GPT-OSS 20B vs Grok 4 Fast (Reasoning)

> Side-by-side benchmark comparison for GPT-OSS 20B and Grok 4 Fast (Reasoning) across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-oss-20b-vs-grok-4-fast-reasoning
- 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 GPT-OSS 20B and Grok 4 Fast (Reasoning).

## Summary

- GPT-OSS 20B and Grok 4 Fast (Reasoning) 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 | GPT-OSS 20B | Grok 4 Fast (Reasoning) |
|----------|----------|----------|
| Creator | OpenAI | xAI |
| Type | Open Weight | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 128K | 2M |
| Independent public score (not head-to-head) | 42.95 | 54.56 |
| Benchmarks Covered | 1 | 1 |
| Pricing (input/output) | $0.00 / $0.00 | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-OSS 20B public-lane score: 38.4 (Estimated · #125/151)
- Grok 4 Fast (Reasoning) public-lane score: Coming soon

### Coding

- Winner: Insufficient shared evidence
- GPT-OSS 20B public-lane score: 40.1 (Estimated · #141/183)
- Grok 4 Fast (Reasoning) public-lane score: 43.9 (Estimated · #119/183)

| Benchmark | GPT-OSS 20B | Grok 4 Fast (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| React Native Evals | 71% | Coming soon | Coming soon |
| Vibe Code Bench | Coming soon | 0.00% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-OSS 20B public-lane score: Coming soon
- Grok 4 Fast (Reasoning) public-lane score: 51.1 (Unranked · 1 rankable row)

### Reasoning

- Winner: Insufficient shared evidence
- GPT-OSS 20B public-lane score: 45 (Unranked · 2 rankable rows)
- Grok 4 Fast (Reasoning) public-lane score: 72.1 (Unranked · 2 rankable rows)

### Knowledge

- Winner: Insufficient shared evidence
- GPT-OSS 20B public-lane score: 40.4 (Estimated · #139/181)
- Grok 4 Fast (Reasoning) public-lane score: 49.2 (Estimated · #94/181)

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-OSS 20B public-lane score: 78.9 (#53/120)
- Grok 4 Fast (Reasoning) public-lane score: 60 (#70/120)

## FAQ

### Can I compare GPT-OSS 20B and Grok 4 Fast (Reasoning) 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

- [GPT-OSS 20B vs GPT-OSS 120B](/compare/gpt-oss-120b-vs-gpt-oss-20b)
- [Grok 4 Fast (Reasoning) vs GPT-OSS 120B](/compare/gpt-oss-120b-vs-grok-4-fast-reasoning)
- [GPT-OSS 20B vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gpt-oss-20b)
- [Grok 4 Fast (Reasoning) vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-grok-4-fast-reasoning)

## Explore More

- [GPT-OSS 20B profile](/models/gpt-oss-20b)
- [Grok 4 Fast (Reasoning) profile](/models/grok-4-fast-reasoning)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)