Is the Bigger Bag Really Cheaper?

Two bags of oats sit on a shop shelf. One costs$ 2, and the other costs$ 3.60. Which is the better buy? The price alone cannot tell you. You also need to know how much each bag contains—and how much you will actually use.

The smaller bag holds 500 grams, while the larger one holds 1,000 grams. To compare them fairly, calculate the price for the same amount. For every 100 grams, the small bag costs 40 cents and the large bag costs 36 cents. The larger bag costs less per gram, even though you pay more at the checkout.

The price for a fixed amount is called the unit price. Some shops show it on the shelf label. If they do not, divide the price by the amount, then multiply by a useful number, such as 100. This is particularly useful when different package sizes make the choice unclear.

Check the units carefully. You cannot directly compare a price per kilogram with a price per 100 grams. Compare similar products, too: plain oats and a mixture containing nuts are not exactly the same food.

Next, consider waste. Suppose a 200-gram bag of fresh salad costs$ 2, while a 400-gram bag costs$ 3. The larger bag costs less by weight. But if you eat only half before the rest goes bad, you have paid$ 3 for the amount you could have bought for$ 2.

Storage space and your budget also matter. A large bag may offer good value but leave little room in your cupboard or cost more than you can spend today. Special offers may have conditions, so read the label before deciding.

The useful question is not simply,"Which package is cheapest?" It is,"Which choice gives me what I need, at a fair price, without buying too much?"