🚀 BitNet b1.58 2B4T - Scaling Native 1-bit LLM
This repository holds the weights for BitNet b1.58 2B4T, the world's first open - source, native 1 - bit Large Language Model (LLM) with 2 billion parameters, developed by Microsoft Research. Trained on a 4 - trillion - token corpus, it shows that native 1 - bit LLMs can match the performance of leading open - weight, full - precision models of similar size while offering significant computational efficiency advantages in terms of memory, energy, and latency.
➡️ Technical Report: BitNet b1.58 2B4T Technical Report
➡️ Official Inference Code: microsoft/BitNet (bitnet.cpp)
✨ Features
- First open - source, native 1 - bit LLM at the 2 - billion parameter scale.
- Demonstrates comparable performance to leading full - precision models with better computational efficiency.
- Trained on a large corpus of 4 trillion tokens.
📦 Installation
Requirements
pip install git+https://github.com/huggingface/transformers.git@096f25ae1f501a084d8ff2dcaf25fbc2bd60eba4
💻 Usage Examples
Basic Usage (with transformers
)
import torch
from transformers import AutoModelForCausalLM, AutoTokenizer
model_id = "microsoft/bitnet-b1.58-2B-4T"
tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(
model_id,
torch_dtype=torch.bfloat16
)
messages = [
{"role": "system", "content": "You are a helpful AI assistant."},
{"role": "user", "content": "How are you?"},
]
prompt = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
chat_input = tokenizer(prompt, return_tensors="pt").to(model.device)
chat_outputs = model.generate(**chat_input, max_new_tokens=50)
response = tokenizer.decode(chat_outputs[0][chat_input['input_ids'].shape[-1]:], skip_special_tokens=True)
print("\nAssistant Response:", response)
Advanced Usage (with bitnet.cpp
)
Please refer to the bitnet.cpp GitHub repository for detailed compilation steps, usage examples, and command - line options.
📚 Documentation
Model Variants
Several versions of the model weights are available on Hugging Face:
Model Details
Property |
Details |
Architecture |
Transformer - based, modified with BitLinear layers (BitNet framework). Uses Rotary Position Embeddings (RoPE), squared ReLU (ReLU²) activation in FFN layers, and subln normalization. No bias terms in linear or normalization layers. |
Quantization |
Native 1.58 - bit weights and 8 - bit activations (W1.58A8). Weights are quantized to ternary values {-1, 0, +1} using absmean quantization during the forward pass. Activations are quantized to 8 - bit integers using absmax quantization (per - token). The model was trained from scratch with this quantization scheme, not post - training quantized. |
Parameters |
~2 Billion |
Training Tokens |
4 Trillion |
Context Length |
Maximum sequence length of 4096 tokens. Recommendation: For optimal performance on tasks requiring very long contexts (beyond the pre - training length or for specialized long - reasoning tasks), perform intermediate long - sequence adaptation/training before the final fine - tuning stage. |
Training Stages |
1. Pre - training: Large - scale training on public text/code and synthetic math data using a two - stage learning rate and weight decay schedule. 2. Supervised Fine - Tuning (SFT): Fine - tuned on instruction - following and conversational datasets using sum loss aggregation and specific hyperparameter tuning. 3. Direct Preference Optimization (DPO): Aligned with human preferences using preference pairs. |
Tokenizer |
LLaMA 3 Tokenizer (vocab size: 128,256). |
Evaluation
BitNet b1.58 2B4T was evaluated against leading open - weight full - precision LLMs of similar size. Below are the key results (all models are instruction - tuned versions):
Benchmark |
LLaMA 3.2 1B |
Gemma - 3 1B |
Qwen2.5 1.5B |
SmolLM2 1.7B |
MiniCPM 2B |
BitNet b1.58 2B |
Memory (Non - emb) |
2GB |
1.4GB |
2.6GB |
3.2GB |
4.8GB |
0.4GB |
Latency (CPU Decoding) |
48ms |
41ms |
65ms |
67ms |
124ms |
29ms |
Energy (Estimated) |
0.258J |
0.186J |
0.347J |
0.425J |
0.649J |
0.028J |
Training Tokens (Pre - train) |
9T* |
2T** |
18T |
11T |
1.1T |
4T |
ARC - Challenge |
37.80 |
38.40 |
46.67 |
43.52 |
44.80 |
49.91 |
ARC - Easy |
63.17 |
63.13 |
76.01 |
62.92 |
72.14 |
74.79 |
OpenbookQA |
34.80 |
38.80 |
40.80 |
46.00 |
40.20 |
41.60 |
BoolQ |
64.65 |
74.22 |
78.04 |
75.78 |
80.67 |
80.18 |
HellaSwag |
60.80 |
57.69 |
68.28 |
71.71 |
70.81 |
68.44 |
PIQA |
74.21 |
71.93 |
76.12 |
76.12 |
76.66 |
77.09 |
WinoGrande |
59.51 |
58.48 |
62.83 |
68.98 |
61.80 |
71.90 |
CommonsenseQA |
58.48 |
42.10 |
76.41 |
63.55 |
71.74 |
71.58 |
TruthfulQA |
43.80 |
38.66 |
46.67 |
39.90 |
41.41 |
45.31 |
TriviaQA |
37.60 |
23.49 |
38.37 |
45.97 |
34.13 |
33.57 |
MMLU |
45.58 |
39.91 |
60.25 |
49.24 |
51.82 |
53.17 |
HumanEval+ |
31.10 |
37.20 |
50.60 |
28.00 |
43.90 |
38.40 |
GSM8K |
38.21 |
31.16 |
56.79 |
45.11 |
4.40 |
58.38 |
MATH - 500 |
23.00 |
42.00 |
53.00 |
17.60 |
14.80 |
43.40 |
IFEval |
62.71 |
66.67 |
50.12 |
57.91 |
36.81 |
53.48 |
MT - bench |
5.43 |
6.40 |
6.12 |
5.50 |
6.57 |
5.85 |
Average |
44.90 |
43.74 |
55.23 |
48.70 |
42.05 |
54.19 |
*LLaMA 3.2 1B uses pruning & distillation.
**Gemma - 3 1B uses distillation.
🔧 Technical Details
The model is based on the Transformer architecture with custom BitLinear
layers. It uses specific quantization techniques during training and inference, which contribute to its computational efficiency. The training process involves multiple stages, including pre - training, supervised fine - tuning, and direct preference optimization.
📄 License
The model weights and code are released under the MIT License.
⚠️ Important Note
Please do NOT expect performance efficiency gains (in terms of speed, latency, or energy consumption) when using this model with the standard transformers library, even with the required fork.
The current execution paths within transformers do not contain the specialized, highly optimized computational kernels required to leverage the advantages of the BitNet architecture. Running the model via transformers will likely result in inference speeds and energy usage comparable to, or potentially worse than, standard full - precision models within this framework on both CPU and GPU.
While you might observe reduced memory usage due to the quantized weights, the primary computational efficiency benefits are not accessible through this standard transformers usage path.
For achieving the efficiency benefits demonstrated in the technical paper, you MUST use the dedicated C++ implementation: bitnet.cpp.
💡 Usage Tip
This model is intended for research and development purposes. While efforts have been made to align it using SFT and DPO, it may still produce outputs that are unexpected, biased, or inaccurate. Please use responsibly.