Most BOM tools price one project at a time. Production rarely works that way: you build several products that share parts, and you need one order that accounts for all of them and for what you already have on the shelf. A purchase list does that.
Add the projects you plan to build to the cart, each with its build quantity, and create a purchase list. PartsBox combines their BOMs by build quantity, removes duplicates, and subtracts the stock you already hold. What is left is the shortfall — the parts you actually need to buy.
The list opens in the same pricing interface you know from pricing a single BOM. You review the offers for each line, choose a specific offer or substitute per part, and adjust quantities to meet a minimum order quantity, reach a price break, or round up to a full reel of 5000. When you settle on an offer for a line, lock it, and later re-pricing will not move it. When the list is ready, switch to the grouped-by-vendor view and PartsBox turns each group into an order. Vendor rules decide which distributors are used — a list can lock its own rule group, one client's rules for one client's work — and you can split a list across several vendors when that is cheaper.
Substitutes stay open until you order. Until you place the purchase, you keep the freedom to pick a specific manufacturer part for a meta-part or an approved substitute, so a shortage on one part never blocks the list.
A purchase list looks at your inventory before it recommends a purchase, and sometimes you need to exclude part of that inventory. A contract manufacturer holding parts consigned by several clients should count only one client's stock when buying for that client. A company with a quarantine or inspection area should ignore stock that is not yet usable. PartsBox filters on storage location, part, lot, and stock, and treats anything that does not match as if it were not there, so the list recommends buying the full quantity. This is the same filtering the advanced build system uses, so purchasing and building see stock the same way. A contract manufacturer who prefixes locations by client — CLIENT-A-, CLIENT-B-, and MTE- for their own parts — can buy for Client A against only the CLIENT-A- and MTE- locations, so another client's consigned stock is never counted.
A purchase list is the first half of purchasing: it works out what to buy, and purchase orders place it. To follow the whole flow from a shortage to received stock, see Purchase parts and receive orders.
Purchase lists are part of purchasing, which starts on the Essentials plan.