I’m a bit of a numbers nerd. Long before groceries began placing the cost per unit size (cents per ounce, dollars per pound, etc.) on price tags, I took a calculator to the market when I shopped. I’d gotten out of the habit because of the convenience of the help the store provided, but I’ve begun taking a calculator once again for three reasons.
Comparing Costs per Unit in Percentages
Let’s say you’re in need of maple syrup. The grocery store sells its own brand of pure, dark maple syrup for $4.32 for a 32 ounce bottle (13.5 cents per ounce) and it also sells a national brand’s pure, dark maple syrup for $3.43 for a 24-ounce bottle (14.3 cents per ounce). You want to know what percent you would save by buying the store brand.
Remembering back to your elementary school days, you punch in (14.3/13.5 =) and you get 1.05926.
You subtract 1 from that number and multiply by 100 and you get 5.926 percent. So you’re saving about 6 percent by buying the store brand.
Comparing the prices of same size quantities
Not wanting to stop the math fun, you say, “What would a 32-ounce size of the brand name cost?” By simply multiplying the per ounce cost (0.143) and the size you want (32 ounces) and you get $4.58.
Calculating the After-Coupon Per Unit Cost
This is a bit of a word problem. A store sells a brand name item that costs $3.83 for a 16-ounce package and its own brand is $4.36 for a 20-ounce package. You have a 25-cent coupon for the name brand and the store will double the coupon (for a total savings of 50 cents). Which is a better deal per ounce?
Answer: After using the coupon, the brand name item is $3.33 for a 16 ounce package, or 20.8 cents per ounce. The store brand is 21.8 cents per ounce. You’re saving about 4.8 percent by using the coupon.
Calculators are especially important when coupons are involved in your purchasing decision since stores don’t post the after-coupon per-unit cost. You begin to realize that sometimes coupons help, and sometimes they don’t. In the example above, if the coupon was not doubled, you would have still paid more per ounce for the brand name item (22.4 cents per ounce).
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Since my cell phone has a calculator (as most do), I always have one on hand. I’ve been using it to calculate post-coupon prices and comparison shop for years. It helps save a lot, and you can often get the name-brand items for less than store brand with coupons, especially when combined with store sales. It also helps to figure out if the family-size or bulk items are actually cheaper than smaller sizes, if those per-unit costs aren’t displayed. The bulk is often actually more expensive.