Text Generation
Transformers
PyTorch
tinymixtral
conversational
custom_code

TinyMixtral v1.1

A small Mixtral-style Mixture-of-Experts causal language model (~432M total / ~176M active parameters), trained from scratch on a single consumer GPU (RTX A5000 24GB).

Quick Start

from transformers import AutoModelForCausalLM, AutoTokenizer

model = AutoModelForCausalLM.from_pretrained(
    "mikecovlee/tinymixtral", trust_remote_code=True
)
tokenizer = AutoTokenizer.from_pretrained("mikecovlee/tinymixtral")

Model Description

TinyMixtral is a research-oriented small MoE language model exploring how far data quality and training recipe can push a model at the ~432M parameter scale. It uses a Mixtral-style sparse MoE architecture with 6 experts and top-2 routing, achieving ~176M active parameters per forward pass.

This checkpoint (v1.1) is the result of a two-stage training pipeline:

  1. Pretrain: 4B tokens on a SmolLM-inspired blend (FineWeb-Edu 89% + Cosmopedia v2 11%) with LR=7e-4
  2. Post-train: 1B tokens on Wikipedia + Cosmopedia v2 (50:50) with LR=2e-5

The v1 model (C4 pretrain) is available at mikecovlee/tinymixtral-v1.0.

Training Details

Parameter Pretrain Post-train
Data FineWeb-Edu + Cosmopedia v2 (89:11) Wikipedia + Cosmopedia v2 (50:50)
Tokens 4B 1B
Steps 162,761 40,691
Learning rate 7e-4 2e-5
Warmup steps 2,000 300
Batch size 24 × 1024 24 × 1024
Optimizer AdamW (β=0.9, 0.95, wd=0.1) same
LR schedule Cosine decay Cosine decay
Precision bf16 bf16
Training time ~84h (RTX A5000) ~20.5h
End loss 2.5 2.5

Evaluation Results

GLUE (zero-shot, 500 samples per task)

Task Metric v1 (C4) v1.1
SST2 accuracy 0.470 0.568
MRPC accuracy / F1 0.338 / 0.069 0.686 / 0.813
QQP accuracy / F1 0.470 / 0.412 0.350 / 0.519
QNLI accuracy 0.494 0.458
RTE accuracy 0.520 0.534
MNLI accuracy 0.348 0.352
MNLI-mm accuracy 0.368 0.364
Mean 0.383 0.515

ARC

Task v1 (C4) v1.1 (0-shot / 5-shot)
ARC-Challenge 0.220 / 0.223 0.249 / 0.254
ARC-Easy 0.311 / 0.320 0.365 / 0.368

Key Findings

  • MRPC F1 improved from 0.069 (random) to 0.813 — data quality alone unlocked paraphrase understanding
  • GLUE Mean improved 34% (0.383 → 0.515) with zero architecture changes
  • Post-training with domain-specific data gave neutral results at this scale — the pretrain recipe is the dominant factor

Architecture

Parameter Value
hidden_size 896
num_layers 10
Attention GQA (14 Q heads / 2 KV heads)
Head dim 64
RoPE theta 1,000,000
Norm RMSNorm
Experts 6 (top-2 routing, SwiGLU)
Vocab size 32,000 (SentencePiece)
Max position 2,048
Total params ~432M
Active params ~176M

Intended Use

This model is intended for research and educational purposes:

  • Studying MoE training dynamics at small scale
  • Experimenting with data quality ablations
  • Learning how to train language models from scratch on consumer hardware

This is a base language model (not instruction-tuned). It performs next-token prediction and is not designed for chat or instruction following.

Limitations

  • 432M parameters limits factual knowledge and reasoning depth
  • Not instruction-tuned — will not follow chat-style prompts reliably
  • English-only training data
  • Random or near-random on several GLUE tasks (QNLI, QQP accuracy)

Citation

@software{tinymixtral2026,
  author = {Michael Lee},
  title = {TinyMixtral: A Small Mixtral-Style MoE Language Model},
  year = {2026},
  url = {https://github.com/mikecovlee/tinymixtral}
}

Links

License

MIT License. Copyright (C) 2026 Michael Lee (李登淳).

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