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Model comparison

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

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
0 category wins1 category wins

Public leaderboard positions: LFM2.5-8B-A1B #166 (Estimated); Mellum2-12B-A2.5B-Thinking 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-Thinking 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-Thinking.

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

Treat this as a split decision. LFM2.5-8B-A1B makes more sense if its workflow fits your team better; Mellum2-12B-A2.5B-Thinking is the better fit if instruction following is the priority.

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-Thinking 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.

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-Thinking
CategoryLFM2.5-8B-A1BΔMellum2-12B-A2.5B-Thinking
Inst. FollowingLFM2.5-8B-A1B68.8Margin 7.7Mellum2-12B-A2.5B-Thinking76.5
KnowledgeLFM2.5-8B-A1BNot measuredMarginNo overlapMellum2-12B-A2.5B-Thinking57.6
MathLFM2.5-8B-A1B50.0MarginNo overlapMellum2-12B-A2.5B-ThinkingNot 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-Thinking
  1. IFEval

    Inst. Following
    Source ↗
    A 91.8%B 76.5%
    Winner: LFM2.5-8B-A1BΔ 15.3
    IFEval: LFM2.5-8B-A1B scored 91.8%; Mellum2-12B-A2.5B-Thinking scored 76.5%. 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-ThinkingComparison
Input / output priceUSD per 1M tokensLFM2.5-8B-A1B$0 input / $0 outputMellum2-12B-A2.5B-ThinkingNot availableA complete price comparison is not available.
Generation speedtokens per secondLFM2.5-8B-A1BNot availableMellum2-12B-A2.5B-ThinkingNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenLFM2.5-8B-A1BNot availableMellum2-12B-A2.5B-ThinkingNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensLFM2.5-8B-A1B128KMellum2-12B-A2.5B-Thinking128KListed context windows are equal.

Benchmark Deep Dive

Agentic
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-ThinkingResult
BFCL v4Source 49.7%45.6%LFM2.5-8B-A1B leads
τ²-bench resultsSource 16.1%Not comparable
Coding
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-ThinkingResult
AA-SciCodeSource 7.8%Not comparable
Reasoning
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-ThinkingResult
AA-LCRSource 0.0%Not comparable
CritPtSource 0.0%Not comparable
Knowledge
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-ThinkingResult
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 86.2%Not comparable
GPQASource 57.6%Not comparable
GPQA-DSource 57.6%Not comparable
Math
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-ThinkingResult
MATH-500Source 88.8%Not comparable
AIME 2025Source 42.5%Not comparable
AIME26Source 50.0%Not comparable
Inst. FollowingMellum2-12B-A2.5B-Thinking wins
BenchmarkLFM2.5-8B-A1BMellum2-12B-A2.5B-ThinkingResult
IFEvalSource 91.8%76.5%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-Thinking?

LFM2.5-8B-A1B and Mellum2-12B-A2.5B-Thinking 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-Thinking?

Mellum2-12B-A2.5B-Thinking has the edge for instruction following in this comparison, averaging 76.5 versus 68.8. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Related Comparisons

Last updated: July 23, 2026

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