Scale or Reason? A Compute-Equivalent Analysis of Reasoning Distillation

Nicolas Boizard, Hippolyte Gisserot-Boukhlef, Kevin El Haddad, Celine Hudelot, Pierre Colombo


Abstract
Distilling reasoning traces from strong teacher models has become the standard recipe for building capable small language models. Yet reasoning traces are 5-20× longer than standard instruction fine-tuning (IFT) outputs, meaning every practitioner who chooses reasoning distillation implicitly forgoes training a larger IFT model on the same compute budget. Whether this trade-off is worthwhile remains unaddressed. We study it with a controlled experiment: a single teacher generates paired IFT and reasoning outputs for identical prompts by toggling only its reasoning mode, isolating supervision format as the sole variable. Training students at five scales (0.5B to 14B) and evaluating on 18 benchmarks, we find that at matched FLOPs, IFT lies on or near the Pareto frontier across the majority of configurations. Reasoning reaches the Pareto frontier only on open-ended tasks at 7B and above. Even there, a sequential curriculum mixing just 25-50% reasoning data with IFT captures most of the accuracy benefit at far lower compute cost.
Anthology ID:
2026.emnlp-main.776
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
Note:
Pages:
18040–18064
Language:
URL:
https://aclanthology.org/2026.emnlp-main.776/
DOI:
Bibkey:
Cite (ACL):
Nicolas Boizard, Hippolyte Gisserot-Boukhlef, Kevin El Haddad, Celine Hudelot, and Pierre Colombo. 2026. Scale or Reason? A Compute-Equivalent Analysis of Reasoning Distillation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 18040–18064, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Scale or Reason? A Compute-Equivalent Analysis of Reasoning Distillation (Boizard et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.776.pdf