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Model comparison

LFM2.5-8B-A1B vs Mellum2-12B-A2.5B-Instruct

Data verified

Head-to-head evidence from 2 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

41.42/100
No comparison
N/A
0 category wins1 category wins

Public leaderboard positions: LFM2.5-8B-A1B #166 (Estimated); Mellum2-12B-A2.5B-Instruct unranked (Not scored). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. LFM2.5-8B-A1B and Mellum2-12B-A2.5B-Instruct share 2 comparable benchmark results. 1 of 8 categories are comparable. 15 results are unique to LFM2.5-8B-A1B; 3 to Mellum2-12B-A2.5B-Instruct.

Updated July 23, 2026
Shared results
2
LFM2.5-8B-A1B only
15
Mellum2-12B-A2.5B-Instruct only
3
Comparable categories
1 / 8

Treat this as a split decision. LFM2.5-8B-A1B makes more sense if you want the stronger reasoning-first profile; Mellum2-12B-A2.5B-Instruct is the better fit if instruction following is the priority or you would rather avoid the extra latency and token burn of a reasoning model.

Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 2 evidence categories; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

LFM2.5-8B-A1B and Mellum2-12B-A2.5B-Instruct finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.

LFM2.5-8B-A1B is the reasoning model in the pair, while Mellum2-12B-A2.5B-Instruct is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use.

Category breakdown

Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.

Category scores and score margins for LFM2.5-8B-A1B and Mellum2-12B-A2.5B-Instruct
CategoryLFM2.5-8B-A1BΔMellum2-12B-A2.5B-Instruct
Inst. FollowingLFM2.5-8B-A1B68.8Margin→ 7.0Mellum2-12B-A2.5B-Instruct75.8
KnowledgeLFM2.5-8B-A1BNot measuredMarginNo overlapMellum2-12B-A2.5B-Instruct40.9
MathLFM2.5-8B-A1B50.0MarginNo overlapMellum2-12B-A2.5B-InstructNot measured

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · LFM2.5-8B-A1BB · Mellum2-12B-A2.5B-Instruct

  1. IFEval

    Inst. Following
    Source ↗
    A 91.8%B 75.8%
    Winner: LFM2.5-8B-A1BΔ 16
    IFEval: LFM2.5-8B-A1B scored 91.8%; Mellum2-12B-A2.5B-Instruct scored 75.8%. LFM2.5-8B-A1B wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructComparison
Input / output priceUSD per 1M tokensLFM2.5-8B-A1B$0 input / $0 outputMellum2-12B-A2.5B-InstructNot availableA complete price comparison is not available.
Generation speedtokens per secondLFM2.5-8B-A1BNot availableMellum2-12B-A2.5B-InstructNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenLFM2.5-8B-A1BNot availableMellum2-12B-A2.5B-InstructNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensLFM2.5-8B-A1B128KMellum2-12B-A2.5B-Instruct128KListed context windows are equal.

Benchmark Deep Dive

Agentic
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructResult
BFCL v4Source 49.7%44.2%LFM2.5-8B-A1B leads
τ²-bench resultsSource 16.1%—Not comparable
Coding
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructResult
AA-SciCodeSource 7.8%—Not comparable
Reasoning
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructResult
AA-LCRSource 0.0%—Not comparable
CritPtSource 0.0%—Not comparable
Knowledge
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructResult
AA-GPQA DiamondSource 51.3%—Not comparable
AA-HLESource 6.9%—Not comparable
AA-Omniscience IndexSource -33.3%—Not comparable
AA-Omniscience AccuracySource 9.4%—Not comparable
AA-Omniscience Hallucination RateSource 47.0%—Not comparable
Artificial Analysis Intelligence IndexSource 8.3%—Not comparable
MMLU-ReduxSource —78.1%Not comparable
GPQASource —40.9%Not comparable
GPQA-DSource —40.9%Not comparable
Math
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructResult
MATH-500Source 88.8%—Not comparable
AIME 2025Source 42.5%—Not comparable
AIME26Source 50.0%—Not comparable
Inst. FollowingMellum2-12B-A2.5B-Instruct wins
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-InstructResult
IFEvalSource 91.8%75.8%LFM2.5-8B-A1B leads
IFBenchSource 56.5%—Not comparable
AA-IFBenchSource 55.6%—Not comparable
Frequently Asked Questions (2)

Which is better, LFM2.5-8B-A1B or Mellum2-12B-A2.5B-Instruct?

LFM2.5-8B-A1B and Mellum2-12B-A2.5B-Instruct are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.

Which is better for instruction following, LFM2.5-8B-A1B or Mellum2-12B-A2.5B-Instruct?

Mellum2-12B-A2.5B-Instruct has the edge for instruction following in this comparison, averaging 75.8 versus 68.8. Inside this category, IFEval is the benchmark that creates the most daylight between them.

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