Reader Rob is a longtime reader and very familiar with our “Target Math” series of posts, so he knows to check the actual price per ounce on items he plans to buy. Especially, he notes, at Target. This recent promotion for laundry detergent demonstrates why.

That’s a nice deal, right? It makes each bottle cost $9.49 as long as you eventually remember to use that gift card. Under normal circumstances, though, the larger bottle of the same product would be a better deal per ounce. It’s not.

“That’s 18.7 cents/oz for the medium-sized bottle, and 19.9 cents/oz for the larger one,” Rob observes. At least the amount of detergent in a load is consistent across the sizes: 1.56 ounces. However, he points out, you don’t even need that gift card as an inducement to buy two smaller bottles instead. You don’t have to buy two bottles to get the gift cards at all, because the smaller bottle is a better deal. “Even without the $5 gift card with purchase of 2 bottles, the smaller package was still the better deal,” Rob observes.

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