Model comparison
GPT-5 nano vs Mellum2-12B-A2.5B-Instruct
Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5 nano #139 (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. GPT-5 nano and Mellum2-12B-A2.5B-Instruct share 0 comparable benchmark results. 0 of 8 categories are comparable. 0 results are unique to GPT-5 nano; 5 to Mellum2-12B-A2.5B-Instruct.
Updated July 23, 2026- Shared results
- 0
- GPT-5 nano only
- 0
- Mellum2-12B-A2.5B-Instruct only
- 5
- Comparable categories
- 0 / 8
Benchmark data for GPT-5 nano and Mellum2-12B-A2.5B-Instruct is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM does not have sourced benchmark coverage for GPT-5 nano yet. This comparison is currently limited to metadata such as context window, reasoning mode, and pricing where available.
GPT-5 nano has the larger context window at 400K, compared with 128K for Mellum2-12B-A2.5B-Instruct.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5 nano | Mellum2-12B-A2.5B-Instruct | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5 nano$0.05 input / $0.4 output | Mellum2-12B-A2.5B-InstructNot available | A complete price comparison is not available. |
| Generation speedtokens per second | GPT-5 nano137 tok/s | Mellum2-12B-A2.5B-InstructNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5 nano83.30 s | Mellum2-12B-A2.5B-InstructNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5 nano400K | Mellum2-12B-A2.5B-Instruct128K | GPT-5 nano lists the larger context window. |
Benchmark Deep Dive
Frequently Asked Questions (3)
Can I compare GPT-5 nano and Mellum2-12B-A2.5B-Instruct on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for GPT-5 nano and Mellum2-12B-A2.5B-Instruct today?
GPT-5 nano: $0.05 input / $0.40 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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