Cooking from scratch vs. buying items ready-made

Today's shopping advice involves math. Sorry, but if you want to save money on groceries, you're going to have to crunch some numbers.

First math problem: Your daughter needs two dozen chocolate-chip cookies for a school party. If you make them from scratch, it's going to take a couple of hours and you will end up with more cookies than you need. If you buy them at the bakery, you'll save time. How much more will you spend? And will they taste just as good as homemade?

"Generally, convenience foods cost more than homemade," said Bill Greer of the Food Marketing Institute in Washington, D.C. "But that isn't always true. Sometimes you can save by purchasing private-label brands or finding things on sale. That's when you should stock up."

We put the theory to the test with several batches of chocolate-chip cookies. The from-scratch cookies cost about 23 cents apiece, compared with Safeway brand slice-and-bake at 16 cents each. We liked the Safeway brand almost as much as the homemade.

Second math problem: You're running late, so you dash into the grocery store and pick up a roasted chicken on your way home from work. Is the guilt you feel by not roasting the chicken yourself justified? Don't kick yourself. We're all busy, and picking up something at the grocery store that's ready to eat is sometimes worth paying extra.

"With the concerns over the economy, most people are eating out less often," said Greer. "Research shows us that 83 percent of Americans eat a home-cooked dinner at least three times a week. But they still want the convenience that comes with prepared foods, and supermarkets are a good source for ready-to-eat or ready-to-cook. Prepared foods may cost more than home-cooked from scratch, but it's still less than eating in a restaurant, and sometimes that convenience is worth paying a little more."

This math problem was easy to figure. At Safeway, a whole raw chicken was $1.59 a pound, but it would take about an hour to cook. A whole raw chicken cut into pieces was $1.99 a pound. A ready-to-eat rotisserie chicken was $7.99, or about $4 a pound. You can find better deals than $7.99, but if convenience is your goal, you don't want to drive across town.

Next math problem: Bananas are 89 cents a pound. You buy three pounds (six bananas). You eat three, but the rest turn black and you toss them into the trash. How much did those three bananas that you didn't eat cost you? $1.34.

In 2004, Timothy W. Jones, an anthropologist at the University of Arizona, measured garbage over 10 years and found that U.S. consumers could save billions of dollars each year if they just paid more attention to how much food they throw away. He estimated that most households waste about 14 percent of their food purchases — more than $600 a year. California households toss out more than 5 million tons of food scraps a year, says the California Integrated Waste Management Board.

The solution: Don't buy more perishables than you can use, even if it means more frequent trips to the grocery store and skipping some bulk-buy deals.

Next math problem: A package of 12 corn tortillas costs $1.65. If you buy a package of 36, it's $1.75. You buy the larger package and freeze what you can't use immediately. A smart buy?

Absolutely, said Greer. "Always check the cost per ounce or unit price on the shelf. Sometimes you might discover that the larger one is actually not your best deal."

As for the tortillas, the 12-pack worked out to 12.7 cents per ounce, while the pack of 36 was 5.9 cents per ounce.

Next math problem: A bag of green salad with dressing to serve four costs $3.49. A head of lettuce is 99 cents, but it will make twice as many servings as the bag. You'll need to add dressing and tomatoes, which are currently about $1.49 a pound.

Is it cost-effective to buy the bag of ready-made salad?

This one is tougher. If you make a salad from scratch, it's going to save you some cash, but if you can't eat it all before it spoils, it's a waste. If your family is eating more salad now that it's easier to make, the ready-made might be worth it. Your call.

You should also consider the higher cost of some pared vegetables before buying them. Peeled baby carrots are about $1.50 a pound. Whole carrots are about half that price. Cut, fresh watermelon is about $4.50 a pound when it's not in season. Wait till August and buy a whole watermelon for less than 50 cents a pound. On the other hand, whole fresh mushrooms usually cost more than sliced ones, so check those unit prices.

OK, math lesson is over.