Model comparison
GPT-4.1 nano vs Mellum2-12B-A2.5B-Thinking
Head-to-head evidence from 2 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-4.1 nano #161 (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. GPT-4.1 nano and Mellum2-12B-A2.5B-Thinking share 2 comparable benchmark results. 2 of 8 categories are comparable. 19 results are unique to GPT-4.1 nano; 3 to Mellum2-12B-A2.5B-Thinking.
Updated July 23, 2026- Shared results
- 2
- GPT-4.1 nano only
- 19
- Mellum2-12B-A2.5B-Thinking only
- 3
- Comparable categories
- 2 / 8
Treat this as a split decision. GPT-4.1 nano makes more sense if instruction following is the priority or you need the larger 1M context window; Mellum2-12B-A2.5B-Thinking is the better fit if knowledge is the priority or you want the stronger reasoning-first profile.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 2 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
GPT-4.1 nano 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 GPT-4.1 nano 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. GPT-4.1 nano gives you the larger context window at 1M, compared with 128K for Mellum2-12B-A2.5B-Thinking.
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 | GPT-4.1 nano | Δ | Mellum2-12B-A2.5B-Thinking |
|---|---|---|---|
| Knowledge | GPT-4.1 nano50.3 | Margin→ 7.3 | Mellum2-12B-A2.5B-Thinking57.6 |
| Inst. Following | GPT-4.1 nano83.2 | Margin← 6.7 | Mellum2-12B-A2.5B-Thinking76.5 |
| Math | GPT-4.1 nano1.0 | MarginNo overlap | Mellum2-12B-A2.5B-ThinkingNot measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
GPQA
KnowledgeA 50.3%B 57.6%Winner: Mellum2-12B-A2.5B-ThinkingΔ 7.3GPQA: GPT-4.1 nano scored 50.3%; Mellum2-12B-A2.5B-Thinking scored 57.6%. Mellum2-12B-A2.5B-Thinking wins this benchmark. - Source ↗
IFEval
Inst. FollowingA 83.2%B 76.5%Winner: GPT-4.1 nanoΔ 6.7IFEval: GPT-4.1 nano scored 83.2%; Mellum2-12B-A2.5B-Thinking scored 76.5%. GPT-4.1 nano wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-4.1 nano | Mellum2-12B-A2.5B-Thinking | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-4.1 nano$0.1 input / $0.4 output | Mellum2-12B-A2.5B-ThinkingNot available | A complete price comparison is not available. |
| Generation speedtokens per second | GPT-4.1 nano181 tok/s | Mellum2-12B-A2.5B-ThinkingNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-4.1 nano0.63 s | Mellum2-12B-A2.5B-ThinkingNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-4.1 nano1M | Mellum2-12B-A2.5B-Thinking128K | GPT-4.1 nano lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding2 benchmarks
Reasoning2 benchmarks
KnowledgeMellum2-12B-A2.5B-Thinking wins10 benchmarks
| Benchmark | GPT-4.1 nano | Mellum2-12B-A2.5B-Thinking | Result |
|---|---|---|---|
| MMLUSource | 80.1% | — | Not comparable |
| GPQASource | 50.3% | 57.6% | Mellum2-12B-A2.5B-Thinking leads |
| Artificial Analysis Intelligence IndexSource | 9.6% | — | Not comparable |
| AA-GPQA DiamondSource | 51.2% | — | Not comparable |
| AA-HLESource | 3.9% | — | Not comparable |
| AA-Omniscience IndexSource | -56.4% | — | Not comparable |
| AA-Omniscience AccuracySource | 13.3% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 80.4% | — | Not comparable |
| MMLU-ReduxSource | — | 86.2% | Not comparable |
| GPQA-DSource | — | 57.6% | Not comparable |
Math1 benchmarks
| Benchmark | GPT-4.1 nano | Mellum2-12B-A2.5B-Thinking | Result |
|---|---|---|---|
| FrontierMath v2 (Tiers 1-3)Source | 1.034% | — | Not comparable |
Multimodal2 benchmarks
Frequently Asked Questions (3)
Which is better, GPT-4.1 nano or Mellum2-12B-A2.5B-Thinking?
GPT-4.1 nano 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 knowledge tasks, GPT-4.1 nano or Mellum2-12B-A2.5B-Thinking?
Mellum2-12B-A2.5B-Thinking has the edge for knowledge tasks in this comparison, averaging 57.6 versus 50.3. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Which is better for instruction following, GPT-4.1 nano or Mellum2-12B-A2.5B-Thinking?
GPT-4.1 nano has the edge for instruction following in this comparison, averaging 83.2 versus 76.5. Inside this category, IFEval is the benchmark that creates the most daylight between them.
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