Grounded Multimodal In-Context Learning for Product Weight Estimation at Scale in E-commerce
Paper · 2026 · Bhavuk Singhal, Arsh Keshari and Ravindra Kumar Yadav
Summary
E-commerce logistics needs product weight to set shipping charges, but sellers rarely state it reliably. Items in the same fine-grained category can also look alike while differing by kilograms. The authors, from Meesho, treat weight estimation as grounded multimodal reasoning. A large vision-language model, Gemini 2.5 Flash, predicts one of 50 discrete 500 g buckets (500 g–25 kg) from a product's image and text, using few-shot in-context examples.
The examples are retrieved automatically from historical listings. Only products with many delivered orders are used, since their declared weights are probably correct. The examples are then sampled so that their bucket frequencies match the sub-category's real weight distribution. The approach was tested on an 18-month corpus spanning 14 sub-categories, with weights verified by experts. It beat multimodal KNN baselines and random exemplar selection.
In a production pilot covering millions of listings, exact-bucket accuracy roughly doubled and shipping revenue leakage fell by about 22%. Because the method needs no retraining, new categories can be added quickly. This makes it a cheaper alternative to manual audits or weighing hardware.
Key points
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Data and baseline:
- The evaluation uses a chronological split: 12 months form the retrieval pool and the next 6 months are the test set.
- The baseline embeds image and text with FLAVA, searches neighbours with FAISS, and predicts using either the Top-1 neighbour or a Top-5 average.
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Number of exemplars: Accuracy grows roughly logarithmically with N_shot. Beyond N_shot = 50, gains fall below 0.5% while cost and latency keep rising non-linearly, so 50 shots was chosen.
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Backbone comparison (accuracy / normalized cost):
Model Accuracy Normalized cost Gemini 2.5 Flash 73.81% 1.0x Gemini 1.5 Pro 74.23% 2.57x GPT-4o 73.89% 5.15x GPT-4o mini 66.45% 0.81x LLaVA-v1.6-34B 56.24% 0.15x Qwen2-VL-72B 59.13% 0.13x -
Production pilot: The system ran on four sub-categories (Compost & Fertilizers, Kitchen Storage, Mops with Bucket, Spice Racks), with these changes:
- accuracy rose from ~37% to ~71%;
- the undercharging rate dropped from ~70% to ~34%;
- underestimation by two or more buckets fell from ~40% to ~5%;
- revenue leakage decreased by ~22%.
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Where the gains come from: The biggest improvements were in heavy buckets, where underestimation costs the most.
Fields, topics and concepts
📚 Shelves 3The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksComputer Vision and Pattern Recognition · 2,869 works
🧭 Topics 2Research subjects and languages the work is about.Language models & pretraining · 3,320 worksVision & language · 657 works
Cite
Cite as Bhavuk Singhal, Arsh Keshari and Ravindra Kumar Yadav. 2026. Grounded Multimodal In-Context Learning for Product Weight Estimation at Scale in E-commerce. Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 6: Industry Track).
@inproceedings{singhal2026grounded,
title = {{Grounded Multimodal In-Context Learning for Product Weight Estimation at Scale in E-commerce}},
author = {Bhavuk Singhal, Arsh Keshari and Ravindra Kumar Yadav},
booktitle = {Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 6: Industry Track)},
year = {2026},
doi = {10.18653/v1/2026.acl-industry.41},
url = {https://doi.org/10.18653/v1/2026.acl-industry.41}
}References
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