Model comparison
Mellum2-12B-A2.5B-Instruct vs Mellum2-12B-A2.5B-Thinking
Head-to-head evidence from 5 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Sibling matchup inside the Mellum2 12B-A2.5B family.
Evidence parity. Mellum2-12B-A2.5B-Instruct and Mellum2-12B-A2.5B-Thinking share 5 comparable benchmark results. 2 of 8 categories are comparable. 0 results are unique to Mellum2-12B-A2.5B-Instruct; 0 to Mellum2-12B-A2.5B-Thinking.
Updated July 23, 2026- Shared results
- 5
- Mellum2-12B-A2.5B-Instruct only
- 0
- Mellum2-12B-A2.5B-Thinking only
- 0
- Comparable categories
- 2 / 8
Mellum2-12B-A2.5B-Instruct makes more sense if you would rather avoid the extra latency and token burn of a reasoning model, while Mellum2-12B-A2.5B-Thinking is the cleaner fit if knowledge is the priority or you want the stronger reasoning-first profile.
Confidence note. This is a partial-evidence comparison with 5 shared benchmark results across 3 evidence categories; 2 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Mellum2-12B-A2.5B-Instruct and Mellum2-12B-A2.5B-Thinking sit in the same Mellum2 12B-A2.5B family. This page is less about two unrelated model lineages and more about how the siblings trade off on benchmark shape, token costs, and practical limits like context window.
Mellum2-12B-A2.5B-Instruct 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.
Mellum2-12B-A2.5B-Thinking 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 | Mellum2-12B-A2.5B-Instruct | Δ | Mellum2-12B-A2.5B-Thinking |
|---|---|---|---|
| Knowledge | Mellum2-12B-A2.5B-Instruct40.9 | Margin→ 16.7 | Mellum2-12B-A2.5B-Thinking57.6 |
| Inst. Following | Mellum2-12B-A2.5B-Instruct75.8 | Margin→ 0.7 | Mellum2-12B-A2.5B-Thinking76.5 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
GPQA
KnowledgeA 40.9%B 57.6%Winner: Mellum2-12B-A2.5B-ThinkingΔ 16.7GPQA: Mellum2-12B-A2.5B-Instruct scored 40.9%; Mellum2-12B-A2.5B-Thinking scored 57.6%. Mellum2-12B-A2.5B-Thinking wins this benchmark. - Source ↗
IFEval
Inst. FollowingA 75.8%B 76.5%Winner: Mellum2-12B-A2.5B-ThinkingΔ 0.7IFEval: Mellum2-12B-A2.5B-Instruct scored 75.8%; Mellum2-12B-A2.5B-Thinking scored 76.5%. Mellum2-12B-A2.5B-Thinking wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Mellum2-12B-A2.5B-Instruct | Mellum2-12B-A2.5B-Thinking | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Mellum2-12B-A2.5B-InstructNot available | Mellum2-12B-A2.5B-ThinkingNot available | A complete price comparison is not available. |
| Generation speedtokens per second | Mellum2-12B-A2.5B-InstructNot available | Mellum2-12B-A2.5B-ThinkingNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Mellum2-12B-A2.5B-InstructNot available | Mellum2-12B-A2.5B-ThinkingNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Mellum2-12B-A2.5B-Instruct128K | Mellum2-12B-A2.5B-Thinking128K | Listed context windows are equal. |
Benchmark Deep Dive
Agentic1 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Instruct | Mellum2-12B-A2.5B-Thinking | Result |
|---|---|---|---|
| BFCL v4Source | 44.2% | 45.6% | Mellum2-12B-A2.5B-Thinking leads |
KnowledgeMellum2-12B-A2.5B-Thinking wins3 benchmarks
Inst. FollowingMellum2-12B-A2.5B-Thinking wins1 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Instruct | Mellum2-12B-A2.5B-Thinking | Result |
|---|---|---|---|
| IFEvalSource | 75.8% | 76.5% | Mellum2-12B-A2.5B-Thinking leads |
Frequently Asked Questions (3)
Which is better, Mellum2-12B-A2.5B-Instruct or Mellum2-12B-A2.5B-Thinking?
Mellum2-12B-A2.5B-Instruct and Mellum2-12B-A2.5B-Thinking are sibling variants in the Mellum2 12B-A2.5B family, so the right pick depends on whether you value the better benchmark line, cheaper tokens, or the larger context window. They are tied on the BenchAlign leaderboard on the current data.
Which is better for knowledge tasks, Mellum2-12B-A2.5B-Instruct or Mellum2-12B-A2.5B-Thinking?
Mellum2-12B-A2.5B-Thinking has the edge for knowledge tasks in this comparison, averaging 57.6 versus 40.9. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Which is better for instruction following, Mellum2-12B-A2.5B-Instruct or Mellum2-12B-A2.5B-Thinking?
Mellum2-12B-A2.5B-Thinking has the edge for instruction following in this comparison, averaging 76.5 versus 75.8. Inside this category, IFEval is the benchmark that creates the most daylight between them.
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