Towards Universal Calibration for In-Context Classification

Awik Dhar, Sunita Sarawagi, Arpit Agarwal


Abstract
In-Context Learning (ICL) has received a lot of interest recently due to its ability to improve classification accuracy for new tasks without having to fine-tune the model over these tasks. However, the impact of ICL on calibration has been far less studied. Recent work has shown that ICL can have a negative impact on calibration due to biased selection of in-context examples. The existing methods for improving ICL calibration require additional task and model-specific training, detracting from the no-fine-tuning convenience of ICL. In this work, we introduce CALIBFORMER, a universal ICL calibrator for classification tasks, that generalizes to new models and tasks without further fine-tuning on these tasks. Specifically, we design a transformer-based calibrator which uses the model predictions on in-context examples to predict a confidence score for the test input. We show that the calibrator trained on three models and ten tasks, is able to generalize/calibrate ICL predictions on several new tasks and four LLMs unseen during training. Even for frontier models like Gemini, CALIBFORMER is able to obtain over 50% reduction in calibration error
Anthology ID:
2026.findings-aacl.224
Volume:
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4389–4418
Language:
URL:
https://aclanthology.org/2026.findings-aacl.224/
DOI:
Bibkey:
Cite (ACL):
Awik Dhar, Sunita Sarawagi, and Arpit Agarwal. 2026. Towards Universal Calibration for In-Context Classification. In Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026, pages 4389–4418, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Towards Universal Calibration for In-Context Classification (Dhar et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-aacl.224.pdf