nanochat

nanochat-d20-sft

Supervised fine-tuned language model from the nanochat project by Andrej Karpathy.

"The best ChatGPT that $100 can buy"

Model Details

• Architecture: GPT-based transformer
• Parameters: 561M
• Layers: 20
• Embedding dimension: 1280
• Attention heads: 10
• KV heads: 10
• Context length: 2048 tokens
• Vocabulary size: 65,536 tokens (BPE tokenizer)
• Training step: 700

Training

This model was trained using the nanochat pipeline, which includes:

1. Base pretraining on web text (FineWeb)
2. Midtraining on curated datasets
3. Supervised fine-tuning (SFT) on conversational data (SmolTalk)

Training cost: ~$100 on 8xH100 GPUs (~4 hours total)

Evaluation Scores (at step 700)

• Validation Loss: 1.015
• MMLU: 33.9%
• ARC-Easy: 48.5%

Usage

Quick Start with nanochat

# Clone and store the path
git clone https://github.com/karpathy/nanochat
cd nanochat
NANOCHAT_DIR=$(pwd)

# Install dependencies
curl -LsSf https://astral.sh/uv/install.sh | sh
uv sync

# Download files
mkdir -p ~/.cache/nanochat/chatsft_checkpoints/d20
mkdir -p ~/.cache/nanochat/tokenizer

cd ~/.cache/nanochat/tokenizer
wget https://huggingface.co/gaviego/nanochat/resolve/main/tokenizer.pkl 

cd ~/.cache/nanochat/chatsft_checkpoints/d20
wget https://huggingface.co/gaviego/nanochat/resolve/main/model_000700.pt
wget https://huggingface.co/gaviego/nanochat/resolve/main/meta_000700.json

# Return to nanochat directory
cd "$NANOCHAT_DIR"
source .venv/bin/activate
python -m scripts.chat_cli

Load Programmatically

import torch
from nanochat.checkpoint_manager import build_model

# Path to checkpoint directory
checkpoint_dir = "~/.cache/nanochat/chatsft_checkpoints/d20"
step = 700
device = torch.device("cpu")  # or "cuda"

# Load model
model, tokenizer, meta = build_model(checkpoint_dir, step, device, phase="eval")

# Generate text
from nanochat.engine import Engine
engine = Engine(model, tokenizer, device=device)
response = engine.generate("Hello, how are you?", max_new_tokens=100)
print(response)

Download with Hugging Face Hub

from huggingface_hub import hf_hub_download

# Download checkpoint
model_path = hf_hub_download(
    repo_id="gaviego/nanochat",
    filename="model_000700.pt"
)
meta_path = hf_hub_download(
    repo_id="gaviego/nanochat",
    filename="meta_000700.json"
)

Files

• model_000700.pt (2.0GB) - PyTorch model checkpoint with weights
• meta_000700.json (264 bytes) - Training metadata and hyperparameters

Limitations

As a micro-scale language model trained on a $100 budget:

• Makes mistakes and hallucinations are common
• Limited reasoning capabilities compared to modern LLMs
• Best suited for educational purposes and experimentation
• Performance roughly comparable to early GPT-2 era models

Citation

If you use this model, please cite the nanochat project:

@misc{nanochat,
  author = {Andrej Karpathy},
  title = {nanochat: The best ChatGPT that $100 can buy},
  year = {2025},
  publisher = {GitHub},
  url = {https://github.com/karpathy/nanochat}
}

License

MIT License (same as nanochat)