tinymixtral-v1.1-1b β€” 1B MoE

Earlier flagship (before v3.0). A wider sparse MoE: ~1.18B total / ~352M active params (top-2 of 8 routed experts), trained on a SmolLM-inspired blend.

Model details

Parameter Value
hidden_size 1024
num_layers 16
Attention GQA (16 heads / 4 KV heads)
Head dim 64
RoPE theta 1,000,000
Norm RMSNorm
Experts 8 routed (top-2)
Expert FFN SwiGLU, intermediate = 2816
Vocab size 32,000
Max position 2,048
Total params ~1.18B
Active params ~352M

Training

Phase Data LR Tokens Steps Time End loss
Pretrain SmolLM blend (89:11) 7e-4 4B 244,141 ~102.5 h 1.9*
Continuation non-overlapping new 4B, same 89:11 4.2e-4 4B 121,921 60.4 h 1.80

* Decay-phase loss plateaued at ~1.9 then spiked to 3.4 in the final ~300 steps as the data stream wrapped back to the start of the corpus.

Data: FineWeb-Edu + Cosmopedia v2 (89:11). Pretrain batch 16 Γ— 1024 (16,384 tokens/step) β†’ 4B tokens in 244,141 steps; warmup 2,000 steps. The continuation added 4B tokens in 121,921 steps (~32k tokens/step).

Evaluation

Measured with lm-evaluation-harness v0.4.12, 0-shot (cuda, bf16).

Task Metric 1B MoE 4B 1B MoE 8B
HellaSwag acc_norm 0.311 0.329
PIQA acc 0.620 0.630
WinoGrande acc 0.510 0.523
ARC-Easy acc 0.463 0.479
ARC-Challenge acc_norm 0.273 0.279
OpenBookQA acc_norm 0.288 0.306
BoolQ acc 0.548 0.620
LAMBADA acc 0.200 0.234
Mean β€” 0.402 0.425

Doubling pretrain tokens improved every task (BoolQ +7.2pp, LAMBADA +3.5pp, mean +2.3pp).

Few-shot: HellaSwag 10-shot acc_norm 0.312 Β· WinoGrande 5-shot acc 0.524 Β· ARC-Easy 25-shot acc_norm 0.468 Β· ARC-Challenge 25-shot acc_norm 0.262.

Comparison with similar models

Same suite and settings, measured locally (lm-evaluation-harness v0.4.12, 0-shot, cuda, bf16):

Task Metric 1B MoE (8B) SmolLM2-360M Qwen3-0.6B
HellaSwag acc_norm 0.329 0.563 0.473
PIQA acc 0.630 0.719 0.673
WinoGrande acc 0.523 0.587 0.563
ARC-Easy acc 0.479 0.705 0.609
ARC-Challenge acc_norm 0.279 0.383 0.340
OpenBookQA acc_norm 0.306 0.372 0.316
BoolQ acc 0.620 0.620 0.643
LAMBADA acc 0.234 0.532 0.401

SmolLM2-360M was trained on 4T tokens and Qwen3-0.6B on 36T tokens, versus 8B tokens for the 1B MoE on a single consumer GPU; the gap is primarily a data-budget difference.

Instruction following (IFEval)

IFEval (instruction-level loose accuracy), --apply_chat_template:

Model IFEval inst-level loose
1B MoE 4B 0.222
1B MoE 5B (post-train) 0.234
1B MoE 8B (continuation) 0.221

Instruction-following stays flat (~0.22) β€” more pretraining tokens do not improve it.

Post-training (negative result)

Post-trained from the lowest-loss pretrain checkpoint with the v1.1 recipe (Wiki + Cosmopedia v2 50:50, 1B tokens, lr 2e-5, warmup 300, WSD, 60,975 steps, ~26 h). Loss fell 2.98 β†’ 1.8 but downstream metrics were unchanged:

Task Pretrain (4B) Post-train (5B)
HellaSwag (acc_norm) 0.311 0.313
PIQA (acc) 0.620 0.623
WinoGrande (acc) 0.510 0.505
ARC-Easy (acc) 0.463 0.465
ARC-Challenge (acc_norm) 0.273 0.272
OpenBookQA (acc_norm) 0.288 0.290
BoolQ (acc) 0.548 0.528
LAMBADA (acc) 0.200 0.195

At this scale, low-LR post-training on a knowledge blend lowers the loss but does not transfer to task ability.

Usage

from transformers import AutoModelForCausalLM, AutoTokenizer

model = AutoModelForCausalLM.from_pretrained("mikecovlee/tinymixtral-v1.1-1b", trust_remote_code=True)
tokenizer = AutoTokenizer.from_pretrained("mikecovlee/tinymixtral-v1.1-1b")

Requires transformers and trust_remote_code=True (custom tinymixtral architecture).

Limitations

  • Base model only: no instruction tuning or safety alignment.
  • Trained on 8B tokens; English-centric. Superseded by the v3.0 flagship.

Family

Naming. The MoE family is published under tinymixtral; the dense 276M iso-active ablation companions use the tinymistral spelling. Both belong to the same project.

Citation

@misc{tinymixtralv1.11b2026,
  title  = {TinyMixtral: a small Mixture-of-Experts language-model family},
  author = {Michael Lee},
  year   = {2026},
  howpublished = {\url{https://huggingface.co/mikecovlee/tinymixtral-v1.1-1b}}
}

License

MIT (Copyright (C) 2026 Michael Lee).

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