Junior has your smile and your spouse’s disposition. Oh, and comic-book superhero powers when it comes to going through diapers quickly. Even the average infant needs changing 2,700 times in the first year. That’s a mountain of diapers—and a pile of money.

Our undercover shoppers checked prices for five diaper brands/sizes at area supermarkets, big-box discounters, membership warehouse clubs, Amazon, and more in seven major metro areas (Boston, Chicago, Minneapolis, Philadelphia, San Francisco, Seattle, and Washington, D.C.). At each store, we also looked for its cheapest available brand, including store brands. Because same-size packages are rarely stocked from store to store, we shopped for the least expensive way to buy diapers on a per-diaper basis for each brand/size we chose. The table below shows the results.

As you can see, per-diaper prices for a typical model—Huggies Little Snugglers, size 2—at surveyed stores ranged from $.17 using Amazon Family with its Subscribe & Save discounts to $.19 at Costco to $.39 at CVS. A 20-cent price difference may not seem like a lot—unless you have small children. Those who change seven diapers a day will quickly realize (assuming sleep deprivation hasn’t destroyed their math skills) that a 20-cent per diaper difference works out to $511 per year in savings or, roughly, what you’d spend in 30 minutes at Disney.

?? For the products we priced, the clear price winner among surveyed retailers was Amazon Family (available only to Prime members), coupled with its Subscribe & Save program (both programs are described below). It offered prices 30 percent lower than the average for all the retailers we shopped, 17 percent lower even than BJ’s, the next-lowest-priced outlet. (BJ's is a chain of warehouse clubs with locations mainly on the east coast.)

Other price leaders were Walmart, Sam’s Club, Costco, and Target, which also offers a subscription discount program.

Here are more tips for saving change on your diaper changes:

• How much you spend on diapers depends as much on how you buy them as on where you buy them. In general, the more nappies per package, the lower the per-unit price. For the most part, we found that the lowest-cost retailers have enough shelf space to stock large-quantity packages. And no matter where you shop, buying a box of 120-plus diapers likely will save you 15 to 20 percent compared to purchasing packages of 20 to 30 diapers.
• Though nabbing large packages can cut per-diaper prices, for an infant don’t buy in bulk: Your little one likely will outgrow small sizes long before going through 234 diapers.
• Several of the lowest-cost sellers charge annual membership fees: BJ’s is $50; Costco’s is $60; and Sam’s Club’s is $45. To get the rock-bottom prices offered by Amazon Family, you’ll have to pay $119 a year for Amazon Prime. You’ll have to decide whether the savings and benefits you get from membership with one of these sellers justifies the annual fee.
• Amazon Family has by far the lowest prices for brand-name diapers, but you can get very low prices from Amazon without signing up for Prime by using its Subscribe & Save. You get a five percent discount on diapers if you use Subscribe & Save to schedule automatic periodic deliveries (with five to 15 percent discounts also available for other items). There are no requirements in terms of how often you have to schedule orders (you could get them every six months), you can cancel or change your order at any time before it is shipped, and you can even skip deliveries. In other words, if you want to place just one order of diapers with Amazon, you can sign up for Subscribe & Save, get a five percent discount on that order, and cancel your subscription afterward without penalty or fear of an avalanche of diapers.
• Target also offers a subscription discount when you buy online. Like Amazon’s program, Target gives a five percent discount when you schedule regular deliveries of household products, and you can cancel subscriptions at any time. But we found Amazon’s subscription prices are about six percent lower than Target’s.
• Try store brands. Among local stores we shopped, we often found store brands offered at prices that were competitive with Amazon Family and the warehouse clubs—and you don’t have to pay a membership fee or wait for deliveries.
• Before trying any new brand or size of diapers, buy a small package to see how it performs for your child. Some parents swear by inexpensive house brands sold at discount chains; others find only more expensive brand-name lines reliable enough. Since every kid is different, you’ll need a little trial and error to find out what’s best for yours.
• Because most local stores stock a small variety of diapers, if you want to buy specialty diapers you might have to shop online. Only some local stores stocked two of the brands of specialty diapers we shopped for: Seventh Generation and Huggies GoodNites.
• Cloth diapers are making a comeback. They’ve been reinvented and are more eco-friendly than disposables. Gone is the need for safety pins: Most cloth diapers are fastened with Velcro or snaps, and can be fitted with washable liners or flushable, biodegradable ones. Converting to cloth might save you money compared to buying disposables at a low-cost retailer—but only if you choose a low-cost brand and wash them yourself. (Diaper cleaning services charge higher fees than what you’d pay for disposables.) Depending on the brand, cloth diaper covers can cost anywhere from $3 to $20 apiece. That means even if you buy a large inventory of cloth diapers—and even if you replace them all annually—they’ll cost you $90 to $600 per year.
• For some families, formula is also a major expense. Our survey included two formula brands and, as with diapers, we shopped for the least expensive way to buy each brand of formula—this time on a per-ounce basis. The stores with the lowest formula prices were, for the most part, the same as those with low diaper prices.
• When using these price data, keep in mind that we shopped a sample of stores for each chain. Because store-to-store differences exist in terms of inventory, prices at your local store may not be the same as at the stores we surveyed, particularly since some stores have more shelf space available for large-size diaper packages.