Stitch Fix uses AI and machine learning models to forecast future demand, optimize inventory levels across warehouses, and inform purchasing decisions for new clothing. These tools are used internally by merchandising and operations teams.

Stitch Fix's algorithms tour describes using a model of system dynamics fitted to historical data to answer questions such as how much of each style to purchase, which items to allocate to which warehouses, and when to retire old inventory. Stitch Fix's VP of Product confirmed proprietary demand prediction tools help anticipate 'not only the styles clients want today but also the trends they'll desire tomorrow.' In 2025, Stitch Fix publicly said its AI merchandising tool contributed to a 20%+ expansion in shoppable Freestyle selection without increasing inventory ownership.