How do I know if buying in bulk is actually cheaper?
Use the bulk buy calculator prompt from the guide. The key math: per-unit cost of bulk vs. per-unit cost on sale. Many items are cheaper bought individually during sales than in bulk at "regular" price. Bulk wins when: the item never goes on sale, you'll use it all before expiration, and you have storage space.
What about Costco vs. Amazon vs. regular stores?
The honest answer: it varies by item. No single retailer wins on everything. AI can compare specific items across retailers: "Is [product] cheaper at Costco, Amazon, or Target per unit, factoring in my Costco membership cost?" The membership fee changes the math — you need to buy enough to justify the annual cost.
Does bulk buying make sense for a household of 1-2 people?
For some items, yes (paper products, cleaning supplies, canned goods). For perishables, rarely — you'll waste more than you save. For items with multiple sizes, sometimes the "bulk" option at a regular store beats the warehouse club bulk option. AI can calculate the break-even for your specific household size.