Model comparison
Grok 4.1 Fast vs LFM2.5-1.2B-Instruct
Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Grok 4.1 Fast #110 (Supported); LFM2.5-1.2B-Instruct #210 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Grok 4.1 Fast and LFM2.5-1.2B-Instruct share 0 comparable benchmark results. 0 of 8 categories are comparable. 13 results are unique to Grok 4.1 Fast; 0 to LFM2.5-1.2B-Instruct.
Updated July 28, 2026- Shared results
- 0
- Grok 4.1 Fast only
- 13
- LFM2.5-1.2B-Instruct only
- 0
- Comparable categories
- 0 / 8
Benchmark data for Grok 4.1 Fast and LFM2.5-1.2B-Instruct is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 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 does not have sourced benchmark coverage for LFM2.5-1.2B-Instruct yet. This comparison is currently limited to metadata such as context window, reasoning mode, and pricing where available.
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 LFM2.5-1.2B-Instruct. Grok 4.1 Fast has the larger context window at 1M, compared with 32K for LFM2.5-1.2B-Instruct.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Grok 4.1 Fast | LFM2.5-1.2B-Instruct | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Grok 4.1 Fast$0.2 input / $0.5 output | LFM2.5-1.2B-Instruct$0 input / $0 output | LFM2.5-1.2B-Instruct has the lower combined listed price. |
| Generation speedtokens per second | Grok 4.1 Fast138 tok/s | LFM2.5-1.2B-InstructNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Grok 4.1 Fast0.54 s | LFM2.5-1.2B-InstructNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Grok 4.1 Fast1M | LFM2.5-1.2B-Instruct32K | Grok 4.1 Fast lists the larger context window. |
Benchmark Deep Dive
Agentic2 benchmarks
Coding1 benchmarks
| Benchmark | Grok 4.1 Fast | LFM2.5-1.2B-Instruct | Result |
|---|---|---|---|
| AA-SciCodeSource | 29.6% | — | Not comparable |
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Grok 4.1 Fast | LFM2.5-1.2B-Instruct | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 16.9% | — | Not comparable |
| AA-GPQA DiamondSource | 63.7% | — | Not comparable |
| AA-HLESource | 5.0% | — | Not comparable |
| AA-Omniscience IndexSource | -50.9% | — | Not comparable |
| AA-Omniscience AccuracySource | 17.0% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 81.8% | — | Not comparable |
Multimodal1 benchmarks
| Benchmark | Grok 4.1 Fast | LFM2.5-1.2B-Instruct | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 48.4% | — | Not comparable |
Inst. Following1 benchmarks
| Benchmark | Grok 4.1 Fast | LFM2.5-1.2B-Instruct | Result |
|---|---|---|---|
| AA-IFBenchSource | 36.5% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare Grok 4.1 Fast and LFM2.5-1.2B-Instruct 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 LFM2.5-1.2B-Instruct today?
Grok 4.1 Fast: $0.20 input / $0.50 output per 1M tokens LFM2.5-1.2B-Instruct: $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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