M3 Scaling Law: Optimizing Multi-Epoch, Multi-Lingual, and Multi-Stage Training for Low-Resource Language Models

Kosuke Akimoto, Taiki Miyagawa, Masafumi Oyamada


Abstract
In this paper, we study a fundamental design problem in pretraining Large Language Models (LLMs) for low-resource language regimes, focusing on cross-family language pairs in which English serves as the high-resource language. Existing works adopt multi-epoch, multi-lingual, and multi-stage training to utilize the limited target-language corpus efficiently, but no prior scaling law can compare recipes spanning these approaches under the same compute budget C and target-language corpus size DT, leaving the optimal training setup unclear. To address this gap, we propose the M3 Scaling Law, a unified predictive model parameterized by the model scale, the number of target-corpus epochs k, the average target-language ratio r, and the final-stage target-language ratio rf, which places monolingual single-stage, multi-lingual single-stage, and multi-lingual multi-stage recipes on a single target-language validation-loss surface. Across three language pairs (English paired with Japanese, Indonesian, and Swahili), it extrapolates to unseen hyperparameter regions more accurately than existing scaling laws. Using M3 as a surrogate objective, we derive two practical guidelines for low-resource LLM pretraining: (i) as DT decreases, the optimal recipe shifts directly from monolingual single-stage to multi-lingual two-stage training at a compute-budget-dependent threshold, with multi-lingual single-stage never optimal in our experimental grid; and (ii) the optimal number of epochs collapses onto a single curve in the scarcity variable DT/D\*(C), where D\*(C) ∝ C𝛼/(𝛼+𝛽) is the monolingual compute-optimal corpus size.
Anthology ID:
2026.findings-emnlp.2315
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
49689–49729
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URL:
https://aclanthology.org/2026.findings-emnlp.2315/
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Cite (ACL):
Kosuke Akimoto, Taiki Miyagawa, and Masafumi Oyamada. 2026. M3 Scaling Law: Optimizing Multi-Epoch, Multi-Lingual, and Multi-Stage Training for Low-Resource Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 49689–49729, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
M3 Scaling Law: Optimizing Multi-Epoch, Multi-Lingual, and Multi-Stage Training for Low-Resource Language Models (Akimoto et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.2315.pdf