How it works

Where the data comes from

Every month a coupon book is published, plus weekly deal posts and holiday ads. We read each page, record the product, item number, discount, sale price and dates, and keep the history.

How predictions work

For each product we merge overlapping sales into one “sale event”, measure the gaps between events, and project the next one. A solid pattern means at least four sales with very similar gaps; likely means a looser but still consistent rhythm; early signal means only two sales so far. When the gaps vary too much we say so instead of guessing.

Limits

• Readings come from scanned pages and can be wrong. Entries we were unsure about are marked.
• Costco may run sales that never appear in the coupon book, and may change a schedule at any time.
• This site is independent and not affiliated with Costco Wholesale.