OpenBMB · 2026-09-07 · major
MiniCPM5-2B — a 2B open model that leads the sub-4B field
MiniCPM5-2B is OpenBMB's new 2.52B-parameter open model for phones and laptops. It averages 53.9 across the maker's benchmark set, ahead of Qwen3.5-4B at 51.1, and ships under Apache-2.0 with a 131K-token context.
OpenBMB's new 2B model takes the top spot among open models under 4B parameters.
Quick facts
| Maker | OpenBMB |
|---|---|
| Parameters | 2.52B total, 1.98B non-embedding |
| Context window | 131,072 tokens |
| License | Apache-2.0 |
| Architecture | Dense LlamaForCausalLM, 42 layers, GQA |
| Released | September 7, 2026 |
| Chip support | 9 chip families via FlagOS |
Benchmarks
| MiniCPM5-2B | 53.9% | |
|---|---|---|
| Qwen3.5-4B | 51.1% | |
| LFM2.5-2.6B | 33.2% | |
| Qwen3.5-2B | 28% |
What is it?
MiniCPM5-2B is a 2.52-billion-parameter dense model built to run on phones, laptops and other hardware without a datacenter GPU. OpenBMB released it on September 7, 2026 under Apache-2.0, with a 131,072-token context window and 1.98B of its parameters outside the embeddings. Artificial Analysis ranks it highest among open-weight models under 4B parameters on its Intelligence Index v4.2.
How does it work?
The architecture is deliberately plain — a standard LlamaForCausalLM stack of 42 layers with 16 query heads and 2 key-value heads for grouped-query attention. Dense means every parameter is active on every token, so memory use stays predictable on a phone in a way a mixture-of-experts model does not. The post-training recipe is where MiniCPM5-2B differs: reinforcement learning paired with on-policy distillation, and OpenBMB published the RL corpus behind it as UltraData-RL-2609.
Why does it matter?
Local models usually give up tool use and long context to fit on a laptop. On OpenBMB's numbers that trade is much smaller here: 97.1 on τ²-Bench tool use and 68.1 on the NoLiMa long-context test, both ahead of Qwen3.5-4B at nearly twice the size. Quantized builds start at 1.56 GB, and FlagOS adaptation means the same weights run on Nvidia, Ascend, Kunlunxin and ARM-v9 hardware.
Who is it for?
people running local models on laptops and phones
Frequently asked questions
- Is MiniCPM5-2B free to use commercially?
- MiniCPM5-2B is published under Apache-2.0, so the weights can be used, modified and shipped in commercial products without a separate licence. OpenBMB also releases the RL training corpus behind it, UltraData-RL-2609, under Apache-2.0, though some upstream datasets inside it carry MIT, CC BY 4.0 and CC BY-SA 4.0 terms that still apply.
- How does MiniCPM5-2B compare to Qwen3.5-4B?
- On OpenBMB's own benchmark table MiniCPM5-2B averages 53.9 against 51.1 for Qwen3.5-4B, a model with roughly twice the parameters. The gaps are widest on long context, where MiniCPM5-2B scores 68.1 on NoLiMa versus 43.5, and on code reasoning, 69.1 on LiveCodeBench versus 56.4. Tool use is 97.1 versus 92.1.
- Where is MiniCPM5-2B weak?
- Artificial Analysis found MiniCPM5-2B weak on knowledge and coding tasks in its own testing, scoring 9% on both Humanity's Last Exam and Terminal-Bench. It rates the agentic side much higher, at an Elo of 831 on GDPval-AA v2. Artificial Analysis also calls it token-efficient for a reasoning model, using 19k output tokens per task.
- Can MiniCPM5-2B run on a phone or a laptop?
- Running MiniCPM5-2B locally is the point of the release. OpenBMB ships GGUF builds at 1.56 GB for 4-bit Q4_K_M, 2.68 GB for 8-bit Q8_0 and 5.04 GB at F16, which llama.cpp, Ollama and LM Studio can load. MLX builds cover Apple Silicon, and FlagOS adaptation extends the same weights to nine chip families.
- How was MiniCPM5-2B post-trained?
- OpenBMB describes the recipe for MiniCPM5-2B as RL plus OPD — reinforcement learning combined with on-policy distillation — and measures it at roughly 11 points of reasoning gain and 7 points on agentic tasks. The RL corpus is public: UltraData-RL-2609 holds 85,995 samples across maths, STEM knowledge, long context and code, each with a checkable answer or executable tests.
Try it
vllm serve openbmb/MiniCPM5-2B --port 8000