GPT-S-1.4M

GPT-S-1.4M a first-generation model in the GPT-S small-model family: 1.4M parameters, 6B training tokens, a custom 4K tokenizer, 5 layers, and all new Exclusive Grouped-query Attention (XGQA), trained from scratch on a 5-source corpus.

See how it compares to similar models here: Open SLM Leaderboard

Benchmarks

All evaluations use zero-shot multiple-choice scoring. Normalized accuracy is reported where available.

Benchmark	Score
HellaSwag	26.89%
ARC-Easy	31.57%
ARC-Challenge	21.93%
ARC Average	26.75%
PIQA	55.17%
ArithMark 2	25.16%

Architecture

Component	Details
Position encoding	RoPE, theta=2,500
Normalization	RMSNorm
Feed-forward	SwiGLU
Attention	Exclusive Grouped-query attention, 4 query heads / 2 KV heads
Embeddings	Weight tied
Context length	384 tokens

Config

vocab_size       = 4,096
hidden_size      = 128
num_layers       = 5
num_heads        = 4
num_kv_heads     = 2
head_dim         = 32
intermediate     = 341
block_size       = 384
rope_theta       = 2,500

Training

GPT-S-1.4M was trained from scratch for 6B tokens on a mixed English corpus built around educational web text, synthetic textbook-style material, and higher-quality web text.

Source	Dataset	Mix	Purpose
FineWeb-Edu	HuggingFaceFW/fineweb-edu	15%	Primary educational web text
Cosmopedia v2	HuggingFaceTB/smollm-corpus	30%	Synthetic textbook-style coverage
FineWeb-HQ	epfml/FineWeb-HQ	20%	Higher-quality general web text
Ultra-FineWeb QA	openbmb/Ultra-FineWeb L3 English QA slice	20%	Question-answer style web text
Ultra-FineWeb Multi-style	openbmb/Ultra-FineWeb L3 English multi-style slice	15%	Broader writing-style coverage

Hyperparameters

Hyperparameter	Value
Optimizer	AdamW
Adam betas	0.9 / 0.95
Weight decay	0.01
Peak learning rate	3.5e-3
Minimum learning rate	0
LR schedule	Warmup-stable-decay
Warmup steps	2,000
Decay start	80% of configured training run
Training tokens	6B
Total batch size	294,912 tokens
Microbatch	256 x 384 tokens
Gradient accumulation steps	3
Gradient clipping	1.0
Precision	bfloat16 autocast

Usage

from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

model_name = "AxiomicLabs/GPT-S-1.4M"

tokenizer = AutoTokenizer.from_pretrained(model_name, trust_remote_code=True)
model = AutoModelForCausalLM.from_pretrained(
    model_name,
    trust_remote_code=True,
    torch_dtype=torch.bfloat16,
    device_map="auto",
)

prompt = "The future of AI is"
inputs = tokenizer(prompt, return_tensors="pt").to(model.device)

with torch.inference_mode():
    output = model.generate(
        **inputs,
        max_new_tokens=80,
        do_sample=True,
        temperature=0.8,
        top_p=0.95,
        repetition_penalty=1.1,
        no_repeat_ngram_size=4,
    )

print(tokenizer.decode(output[0], skip_special_tokens=True))

Limitations

This is a very small base language model. It is not instruction tuned, has limited factual capacity, and uses a 384-token context window.