# Gemma 3 (27B)

> Gemma's flagship text stack leans on local attention more aggressively than Gemma 2.

| Property | Value |
| --- | --- |
| Lab | Google (United States) |
| Released | 2025-03-11 |
| Decoder type | Dense |
| Family | Dense |
| Scale | 27B parameters |
| Context window | 128,000 tokens |
| Attention | GQA with QK-Norm and 5:1 sliding-window/global attention |
| Layer mix | 52 sliding-window + 10 global |
| KV cache / token (bf16) | 496 KiB (Very high) |
| License | Gemma Terms of Use + Gemma Prohibited Use Policy |

**Key detail:** Built around a 27B sweet spot with heavier local attention and a large 262k multilingual vocabulary.

## Architecture concepts

- [QK-Norm (QK-Norm)](https://llm-atlas-7or.pages.dev/concepts/qk-norm.md): RMSNorm applied to queries and keys before attention to keep logits well-behaved.
- [Grouped-Query Attention (GQA)](https://llm-atlas-7or.pages.dev/concepts/gqa.md): Several query heads share one key/value head, shrinking the KV cache with little quality loss.
- [Sliding Window Attention (SWA)](https://llm-atlas-7or.pages.dev/concepts/swa.md): Some layers only attend to a local window of recent tokens instead of the whole context.

## Benchmark (Artificial Analysis Intelligence Index)

- AA Intelligence Index v4.3.2: total 4.9 (General 6.9, Scientific 2.2, Coding 11.6, Agents 0)

## Links

- Architecture diagram: https://sebastianraschka.com/llm-architecture-gallery/images/architectures/gemma-3-27b.webp
- View in article: https://magazine.sebastianraschka.com/p/the-big-llm-architecture-comparison#%C2%A74-mistral-small-31
- From scratch: https://github.com/rasbt/LLMs-from-scratch/tree/main/ch05/12_gemma3
- config.json: https://huggingface.co/google/gemma-3-27b-it/blob/main/config.json
- License: https://ai.google.dev/gemma/prohibited_use_policy
- Tech report: https://arxiv.org/pdf/2503.19786
- Source card (source of truth): https://sebastianraschka.com/llm-architecture-gallery/#card-gemma-3-27b
- Web page: https://llm-atlas-7or.pages.dev/models/gemma-3-27b/
- JSON: https://llm-atlas-7or.pages.dev/api/models/gemma-3-27b.json

_Data from Sebastian Raschka's LLM Architecture Gallery (https://sebastianraschka.com/llm-architecture-gallery/). Synced 2026-11-04._