Towards a Comprehensive Scaling Law of Mixture-of-Experts

Guoliang Zhao, Yuhan Fu, Shuaipeng Li, Samm Sun, Ruobing Xie, An Wang, Weidong Han, Zhen Yang, Weixuan Sun, Yudong Zhang, Cheng-zhong Xu, Di Wang, Jie Jiang


Abstract
Mixture-of-Experts (MoE) has emerged as the dominant paradigm for parameter-efficient scaling and cost-effective deployment of Large Language Models (LLMs). However, scaling laws developed for dense models are fundamentally inapplicable to MoE architectures, owing to three critical challenges: the multiplicity of governing factors, their intricate interdependencies, and the non-monotonic nature of their effects on model performance. These challenges collectively demand a rigorous and fine-grained investigation into MoE-specific scaling laws. In this work, we present a systematic decomposition of MoE configurations, identifying five key factors that influence model performance from both size and structural perspectives: data size (D), total model size (N), activated model size (Na), number of active experts (G), and ratio of shared experts (S). We conduct 450 controlled experiments to characterize the marginal effects of each factor, culminating in a comprehensive and precise joint MoE scaling law. Building on this foundation, we derive the theoretically optimal and practically efficiency-aware optimal configurations for G, S and Na/N with detailed analyses. Our findings reveal that the optimal settings for G and S are invariant to model and data size, while the optimal activation ratio Na/N grows sparser as N increases. Our proposed MoE scaling law provides accurate and insightful guidance for future MoE model design and training.
Anthology ID:
2026.emnlp-main.1227
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
27994–28022
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URL:
https://aclanthology.org/2026.emnlp-main.1227/
DOI:
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Cite (ACL):
Guoliang Zhao, Yuhan Fu, Shuaipeng Li, Samm Sun, Ruobing Xie, An Wang, Weidong Han, Zhen Yang, Weixuan Sun, Yudong Zhang, Cheng-zhong Xu, Di Wang, and Jie Jiang. 2026. Towards a Comprehensive Scaling Law of Mixture-of-Experts. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 27994–28022, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Towards a Comprehensive Scaling Law of Mixture-of-Experts (Zhao et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1227.pdf