How to Fine-Tune Segment Anything 3 (SAM 3) on a Custom Dataset

Segment Anything 3 (SAM 3), developed by Meta and released on November 19, 2025, is a cutting-edge zero-shot instance segmentation model that can generate precise segmentation masks for objects in images or videos using text or point prompts. This guide provides a comprehensive walkthrough on fine-tuning SAM 3 with a custom dataset to enhance its performance in specific domains, demonstrating steps such as dataset preparation, version creation, and initiating a training job. It also details deploying the fine-tuned model using Roboflow Workflows, which allows for cloud or local deployment via a serverless API or an open-source inference server. SAM 3's unique feature, Promptable Composable Segmentation (PCS), enables it to identify objects based on text prompts, making it a versatile tool for various segmentation tasks.