Model comparison
Grok 4.1 Fast vs Llama 3.1 405B
Head-to-head evidence from 11 shared benchmark results across 5 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Grok 4.1 Fast #107 (Supported); Llama 3.1 405B #102 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Grok 4.1 Fast and Llama 3.1 405B share 11 comparable benchmark results. 0 of 8 categories are comparable. 2 results are unique to Grok 4.1 Fast; 0 to Llama 3.1 405B.
Updated July 20, 2026- Shared results
- 11
- Grok 4.1 Fast only
- 2
- Llama 3.1 405B only
- 0
- Comparable categories
- 0 / 8
Benchmark data for Grok 4.1 Fast and Llama 3.1 405B is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 11 shared benchmark results across 5 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
Grok 4.1 Fast is priced at $0.20 input / $0.50 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for Llama 3.1 405B. Grok 4.1 Fast has the larger context window at 1M, compared with 128K for Llama 3.1 405B.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Grok 4.1 Fast | Llama 3.1 405B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Grok 4.1 Fast$0.2 input / $0.5 output | Llama 3.1 405B$0 input / $0 output | Llama 3.1 405B has the lower combined listed price. |
| Generation speedtokens per second | Grok 4.1 Fast138 tok/s | Llama 3.1 405B29 tok/s | Grok 4.1 Fast has the higher measured throughput. |
| First-answer latencyseconds to first token | Grok 4.1 Fast0.54 s | Llama 3.1 405B2.19 s | Grok 4.1 Fast reaches the first token sooner. |
| Context windowmaximum listed tokens | Grok 4.1 Fast1M | Llama 3.1 405B128K | Grok 4.1 Fast lists the larger context window. |
Benchmark Deep Dive
Agentic2 benchmarks
Coding1 benchmarks
| Benchmark | Grok 4.1 Fast | Llama 3.1 405B | Result |
|---|---|---|---|
| AA-SciCodeSource | 29.6% | 29.9% | Llama 3.1 405B leads |
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Grok 4.1 Fast | Llama 3.1 405B | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 16.9% | 8.5% | Grok 4.1 Fast leads |
| AA-GPQA DiamondSource | 63.7% | 51.5% | Grok 4.1 Fast leads |
| AA-HLESource | 5.0% | 4.2% | Grok 4.1 Fast leads |
| AA-Omniscience IndexSource | -50.9% | -17.3% | Llama 3.1 405B leads |
| AA-Omniscience AccuracySource | 17.0% | 22.3% | Llama 3.1 405B leads |
| AA-Omniscience Hallucination RateSource | 81.8% | 51.0% | Llama 3.1 405B leads |
Multimodal1 benchmarks
| Benchmark | Grok 4.1 Fast | Llama 3.1 405B | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 48.4% | — | Not comparable |
Inst. Following1 benchmarks
| Benchmark | Grok 4.1 Fast | Llama 3.1 405B | Result |
|---|---|---|---|
| AA-IFBenchSource | 36.5% | 39.0% | Llama 3.1 405B leads |
Frequently Asked Questions (3)
Can I compare Grok 4.1 Fast and Llama 3.1 405B on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for Grok 4.1 Fast and Llama 3.1 405B today?
Grok 4.1 Fast: $0.20 input / $0.50 output per 1M tokens Llama 3.1 405B: $0.00 input / $0.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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