SALT LAKE CITY — If you have a family, you know grocery shopping can eat up a big chunk of your monthly budget.

According to the U.S. Department of Agriculture, a family of four that’s counting its pennies can wind up spending more than $600 a month. A family that’s not as thrifty can wind up spending as much as $1,300 a month.

With that in mind, the KSL Investigators wanted to know if purchasing a warehouse membership would shave a significant amount of money off a family’s grocery budget.

The cost to shop at a warehouse club depends on the type of membership a customer purchases. The basic annual membership for Costco is $60, and at Sam’s, it’s $45. An enhanced yearly membership costs more — $120 and $100 respectively — but earns cash back with purchases.

With a list of 58 items — from eggs, to milk, diapers, batteries, snacks, poultry and a whole lot more — the KSL Investigators hit aisles at Winco, Smith’s, and Walmart. They also researched the cost of similar items at online retail giant Amazon.

They wanted to know how prices at Costco and Sam’s Club stacked up.

To keep their survey as fair as possible, the team compared regular, not sale prices; and did not use any coupon discounts for the test. They also stuck with name-brand items instead of the traditionally less-expensive store or generic brand.

After hours of pushing carts around while jotting down prices and quantities, they grabbed calculators and started tallying price per ounce, price per item, price per pound.

And with the results, the team was sold: If a family wants to cut its grocery budget, a warehouse membership is worth the cost to shop.

Teresa Hunsaker, a consumer science educator at Utah State University, agrees. “It’ll pay for itself,” she said.

Sam's Club offered the best deal for 34 items, or more than half of the items on the team’s shopping list. For example, milk was $3.21 a gallon cheaper than ordering it from Amazon. The team saved $1.60 on 10 yogurts compared to Smith’s. Sam's beat Costco’s price on lunchmeat by $2.50 per pound.

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Overall, Costco's prices came in second and Winco was a close third. Amazon and Walmart finished behind Smith’s in our survey.

Bottom line: regular trips to the grocery aisles at the warehouse club can recoup the annual fee and, in the long run, save money on groceries. But there’s a caveat.

“It’s probably worth it if I have done my homework on prices, if I have taken a look at what we actually need, in the quantities that we will actually use them,” Hunsaker said.

Warehouse stores sell items in bulk and, in some cases, even a family of four might not eat through a gallon of ranch salad dressing before it spoils or a six-pound bag of pretzels before it goes stale. And figuring out where to store 45 rolls of toilet paper can be … well, challenging.

In fact, a recent study by Dartmouth's Tuck School of Business said warehouse shopping can make you spend 5 percent more because you can overspend. Again, buying in bulk can mean you’ll end up feeding your garbage disposal with a lot of food that’s gone bad before it’s eaten.

Plus, consider all those impulse buys that can happen inside a warehouse store packed with everything from kid’s clothes to office chairs. So, maybe it's not always about price per ounce.

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