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Model comparison

Claude Sonnet 4.5 vs Mellum2-12B-A2.5B-Instruct

Data verified

Head-to-head evidence from 1 shared benchmark result across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.

53.61/100
No comparison
N/A
1 category wins0 category wins

Public leaderboard positions: Claude Sonnet 4.5 #96 (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. Claude Sonnet 4.5 and Mellum2-12B-A2.5B-Instruct share 1 comparable benchmark result. 1 of 8 categories are comparable. 11 results are unique to Claude Sonnet 4.5; 4 to Mellum2-12B-A2.5B-Instruct.

Updated July 23, 2026
Shared results
1
Claude Sonnet 4.5 only
11
Mellum2-12B-A2.5B-Instruct only
4
Comparable categories
1 / 8

Treat this as a split decision. Claude Sonnet 4.5 makes more sense if knowledge is the priority or you need the larger 200K context window; Mellum2-12B-A2.5B-Instruct is the better fit if its strengths line up with your actual workload.

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

Why this result

Claude Sonnet 4.5 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.

Claude Sonnet 4.5 gives you the larger context window at 200K, compared with 128K for Mellum2-12B-A2.5B-Instruct.

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 Claude Sonnet 4.5 and Mellum2-12B-A2.5B-Instruct
CategoryClaude Sonnet 4.5ΔMellum2-12B-A2.5B-Instruct
KnowledgeClaude Sonnet 4.583.4Margin← 42.5Mellum2-12B-A2.5B-Instruct40.9
AgenticClaude Sonnet 4.555.4MarginNo overlapMellum2-12B-A2.5B-InstructNot measured
CodingClaude Sonnet 4.577.2MarginNo overlapMellum2-12B-A2.5B-InstructNot measured
ReasoningClaude Sonnet 4.513.6MarginNo overlapMellum2-12B-A2.5B-InstructNot measured
MathClaude Sonnet 4.511.2MarginNo overlapMellum2-12B-A2.5B-InstructNot measured
Inst. FollowingClaude Sonnet 4.5Not measuredMarginNo overlapMellum2-12B-A2.5B-Instruct75.8

Decisive benchmark drivers

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

More
A · Claude Sonnet 4.5B · Mellum2-12B-A2.5B-Instruct

  1. GPQA

    Knowledge
    Source ↗
    A 83.4%B 40.9%
    Winner: Claude Sonnet 4.5Δ 42.5
    GPQA: Claude Sonnet 4.5 scored 83.4%; Mellum2-12B-A2.5B-Instruct scored 40.9%. Claude Sonnet 4.5 wins this benchmark.

Operational comparison

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

MetricClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructComparison
Input / output priceUSD per 1M tokensClaude Sonnet 4.5$3 input / $15 outputMellum2-12B-A2.5B-InstructNot availableA complete price comparison is not available.
Generation speedtokens per secondClaude Sonnet 4.5Not availableMellum2-12B-A2.5B-InstructNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Sonnet 4.5Not availableMellum2-12B-A2.5B-InstructNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Sonnet 4.5200KMellum2-12B-A2.5B-Instruct128KClaude Sonnet 4.5 lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
Terminal-Bench 2.0Source 50%—Not comparable
OSWorld-VerifiedSource 61.4%—Not comparable
VITA-BenchSource 17.0%—Not comparable
Gert LabsSource 48.51%—Not comparable
JobBenchSource 27.7%—Not comparable
BFCL v4Source —44.2%Not comparable
Coding
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
SWE-bench VerifiedSource 77.2%—Not comparable
Reasoning
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
ARC-AGI-2Source 13.6%—Not comparable
KnowledgeClaude Sonnet 4.5 wins
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
GPQASource 83.4%40.9%Claude Sonnet 4.5 leads
MMLU-ReduxSource —78.1%Not comparable
GPQA-DSource —40.9%Not comparable
Math
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
AIME 2025Source 87%—Not comparable
FrontierMath v2 (Tiers 1-3)Source 13.495%—Not comparable
FrontierMath v2 (Tier 4)Source 4.167%—Not comparable
Multimodal
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
Design Arena WebsiteSource 1219—Not comparable
Inst. Following
BenchmarkClaude Sonnet 4.5Mellum2-12B-A2.5B-InstructResult
IFEvalSource —75.8%Not comparable
Frequently Asked Questions (2)

Which is better, Claude Sonnet 4.5 or Mellum2-12B-A2.5B-Instruct?

Claude Sonnet 4.5 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 knowledge tasks, Claude Sonnet 4.5 or Mellum2-12B-A2.5B-Instruct?

Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 40.9. Inside this category, GPQA is the benchmark that creates the most daylight between them.

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