The apparel industry uniquely faces the challenge of combining characteristics of make-to-stock manufacturing with consumer-driven fashion volatility. Improving demand planning at the SKU and sub-SKU level can mean the difference between success and failure of a new product introduction or an entire season. This white paper discusses how proportional profiles (also called distributions or “size curves”) are used to parse an item’s demand forecast down to the attribute level (by color, size, fabric, and more) to help develop a good attribute-level supply chain forecast; and how to automate the creation and management of proportional profiles spanning attributes such as gender, size, color, width, trim, fabric, channel, region, label/brand, and much more, for entire collections of apparel items.