How to Read a Price History Chart Before You Buy

Read a price history chart in under a minute: find the floor, check how recent it is, and recognize the five shapes that tell a real deal from a marked-up one.

"30% off" tells you nothing until you know what it's 30% off of, and the regular price on the tag is set by the retailer, not by what the item has actually sold for. A price history chart swaps that number for the real record. Once you know what to look for, reading one takes less than a minute.

Find the floor first

ShelfAware records a product's price every time it changes. The lowest point on the chart is the cheapest that item has sold for while ShelfAware has been watching it. If today's price matches or beats it, you're about as close to a guarantee as pricing gets.

Then check how recent it was

A low from last month counts for more than one from a year ago, since prices and availability drift. Also keep in mind that a chart only goes back as far as ShelfAware has been tracking that item. A short history is still useful. It's just less conclusive.

Five shapes worth recognizing

A dip that comes back up. A temporary sale, like a Walmart rollback. If you missed it, there may well be another one.
A step down that stays down.A permanent markdown, usually clearance. It can step down again if the item still doesn't sell.
A sawtooth. The price goes up and down on a regular rhythm. Never pay the high side. Wait for the next low.
A jump right before a "sale."The regular price went up, then got cut back. The real discount is smaller than the tag says, and sometimes it's zero.
Flat for months, then a new low. The rarest shape and the strongest signal. Something changed, and it may not last.

One price for the country, or one per store

At retailers that price nationally, like Best Buy, Staples, and Sport Chek, one history covers every store. At Canadian Tire, Home Depot, and Home Hardware, prices can differ between locations, so ShelfAware records them store by store. For those retailers, the store you'd actually shop at is the one whose history counts.

When you've found the floor, set a price alert at or near it and let the chart do the waiting. Search a product to see its chart, and read how to pick an alert target if you're not sure where to set it.