t5gemma.md

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*This model was released on 2025-04-08 and added to Hugging Face Transformers on 2025-06-25.*
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# T5Gemma

T5Gemma (aka encoder-decoder Gemma) was proposed in a [research paper](https://huggingface.co/papers/2504.06225) by Google. It is a family of encoder-decoder large language models, developed by adapting pretrained decoder-only models into encoder-decoder. T5Gemma includes pretrained and instruction-tuned variants. The architecture is based on transformer encoder-decoder design following T5, with improvements from Gemma 2: GQA, RoPE, GeGLU activation, RMSNorm, and interleaved local/global attention.

T5Gemma has two groups of model sizes: 1) [Gemma 2](https://ai.google.dev/gemma/docs/core/model_card_2) sizes (2B-2B, 9B-2B, and 9B-9B), which are based on the official Gemma 2 models (2B and 9B); and 2) [T5](https://huggingface.co/papers/1910.10683) sizes (Small, Base, Large, and XL), where are pretrained under the Gemma 2 framework following T5 configuration. In addition, we also provide a model at ML size (medium large, ~2B in total), which is in-between T5 Large and T5 XL.

The pretrained variants are trained with two objectives: prefix language modeling with knowledge distillation (PrefixLM) and UL2, separately. We release both variants for each model size. The instruction-turned variants was post-trained with supervised fine-tuning and reinforcement learning.

> [!TIP]
> Click on the T5Gemma models in the right sidebar for more examples of how to apply T5Gemma to different language tasks.

The example below demonstrates how to chat with the model with [`Pipeline`] or the [`AutoModel`] class, and from the command line.

<hfoptions id="usage">
<hfoption id="Pipeline">

```python
import torch
from transformers import pipeline

pipe = pipeline(
    "text2text-generation",
    model="google/t5gemma-2b-2b-prefixlm-it",
    dtype=torch.bfloat16,
    device_map="auto",
)

messages = [
    {"role": "user", "content": "Tell me an unknown interesting biology fact about the brain."},
]
prompt = pipe.tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)

pipe(prompt, max_new_tokens=32)
```

</hfoption>
<hfoption id="AutoModel">

```python
# pip install accelerate
import torch
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM

tokenizer = AutoTokenizer.from_pretrained("google/t5gemma-2b-2b-prefixlm-it")
model = AutoModelForSeq2SeqLM.from_pretrained(
    "google/t5gemma-2b-2b-prefixlm-it",
    device_map="auto",
    dtype=torch.bfloat16,
)

messages = [
    {"role": "user", "content": "Tell me an unknown interesting biology fact about the brain."},
]
input_ids = tokenizer.apply_chat_template(messages, return_tensors="pt", return_dict=True, add_generation_prompt=True).to(model.device)

outputs = model.generate(**input_ids, max_new_tokens=32)
print(tokenizer.decode(outputs[0]))
```

</hfoption>
<hfoption id="transformers CLI">

```bash
echo -e "Write me a poem about Machine Learning. Answer:" | transformers run --task text2text-generation --model google/t5gemma-2b-2b-prefixlm --device 0
```

</hfoption>
</hfoptions>

## T5GemmaConfig

[[autodoc]] T5GemmaConfig

## T5GemmaModuleConfig

[[autodoc]] T5GemmaModuleConfig

## T5GemmaModel

[[autodoc]] T5GemmaModel
    - forward

## T5GemmaEncoderModel

[[autodoc]] T5GemmaEncoderModel
    - forward

## T5GemmaForConditionalGeneration

[[autodoc]] T5GemmaForConditionalGeneration
    - forward

## T5GemmaForSequenceClassification

[[autodoc]] T5GemmaForSequenceClassification
    - forward

## T5GemmaForTokenClassification

[[autodoc]] T5GemmaForTokenClassification
    - forward