Back to Reading List
[Architecture]·PAP-X5QLCL·March 17, 2026

Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsity

William Fedus, Barret Zoph, Noam Shazeer

4 min readArchitectureMoEScalingEfficiency

Core Insight

Switch Transformers scale models to trillion parameters with efficient sparsity and faster pre-training.

Origin Story

arXiv preprint, January 2021Google Brain2k citationsNoam Shazeer, William Fedus et al.

The Room

Three engineers at Google Brain, 2020. They gather in a sparse and minimalist office, the quiet hum of computers a constant backdrop. Their minds are buzzing, not with excitement, but with a nagging problem: scaling AI models is like building skyscrapers with a single crane. Too slow, too costly. Frustration lingers in the air.

The Bet

Instead of pushing dense models further, they gambled on a lighter path: sparsity. What if only parts of a model were active at a time? One evening, William almost deleted his code, doubting if this sparse approach could even work. But they pressed on, convinced this was the future despite the risks.

The Blast Radius

Without this paper, trillion-parameter models like PaLM and GPT-3 might still be dreams. Each of these models built on the idea of sparsity, making AI more accessible and efficient. The authors continued to innovate — William and Noam remain pivotal figures in AI, shaping the next wave of intelligent systems.

PaLMGPT-3Megatron-Turing NLG

Knowledge Prerequisites

git blame for knowledge

To fully understand Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsity, trace this dependency chain first. Papers in our library are linked — click to read them.

DIRECT PREREQIN LIBRARY
Attention Is All You Need

You need to understand the attention mechanisms which are foundational to transformer architectures, including Switch Transformers.

transformer architectureattention mechanismencoder-decoder structure
DIRECT PREREQIN LIBRARY
BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding

This paper introduces bidirectional transformers and helps understand how transformers can be applied for NLP tasks, a basis for the Switch Transformer model.

bidirectional transformerpre-trainingNLP applications
DIRECT PREREQIN LIBRARY
Scaling Laws for Neural Language Models

This paper discusses the scaling behaviors of model parameters and implications for training efficiency, which are crucial for understanding the scaling approach used in Switch Transformers.

model scalingparameter efficiencytraining cost
DIRECT PREREQIN LIBRARY
FlashAttention: Fast and Memory-Efficient Exact Attention with IO-Awareness

Understanding memory-efficient attention mechanisms like FlashAttention can provide insights into the efficient sparsity techniques used by Switch Transformers.

memory efficiencysparse attentionIO-awareness
DIRECT PREREQIN LIBRARY
Tree of Thoughts: Deliberate Problem Solving with Large Language Models

This paper explores deliberate problem-solving approaches in large models, which can contextualize the operational efficiencies of models like Switch Transformers.

problem-solvinginference strategieslarge model efficiencies

YOU ARE HERE

Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsity

In Plain English

s use a to assign different parameters for each input, resulting in sparse activations. This innovative architecture scales to trillion-parameter models with a 7x increase in pre-training speed using the same computational power.

Explained Through an Analogy

Imagine a tailor who picks the perfect thread color for each garment, cutting waste and speeding up production. Switch Transformers, like this tailor, selectively and efficiently activate the most relevant 'threads' of their vast parameter 'fabric' for each task.

Go deeper for $6/mo

Everything a PM needs to turn this paper into a competitive edge — in under 10 minutes.

  • 2-page deep-dive article
  • Highlighted key passages
  • Expert-mode reading layer
  • PM Action Plan — 3 moves
  • Use cases for your product
  • Meeting talking points
  • Interactive paper simulator
  • Test Your Edge quiz

Already subscribed?

Log in

How grounded is this content?

Metrics are computed from available source text only — abstract, summary, and impact fields ingested into this system. Full paper PDF is not ingested; numerical claims that originate from within the paper body will not appear in these scores.

Source Richness88%

7 of 8 content fields populated. More fields = better-grounded generation.

Source Depth~240 words

Total source text analyzed by the model. Includes extended deep-dive summary — high confidence.

Methodology: Number grounding uses regex digit extraction against source text. Quote traceability uses token set intersection on content words stripped of stop-words. Neither metric validates semantic correctness or factual accuracy against the original paper. For full verification, cross-reference with the original paper via the arXiv link above.