I have to admit that math isn’t really my thing. Sure, I can hold my own when it comes to early elementary skills, but I’d rather diagram a sentence any ‘ol day of the week. It’s too bad that diagramming sentences doesn’t save a single dime at the grocery store. Bummer!
Thankfully, the math skills required for figuring unit prices, and therefore discovering the best price, are fairly simple and can be accomplished easily with the help of a calculator and a few tips. Of course, most grocery stores also list the unit price on the shelf sticker, but that doesn’t help much when it comes to produce or sale items. Bummer, again!
Decide What Units to Use
Before we start, we need to decide what units to use when comparing prices. Sometimes there’s an obvious choice, but don’t overlook how you plan to use the product.
For example, if I’m buying a children’s over-the-counter medication, I’ll figure out how many doses are in each package before I figure out the unit price. If my sick kid has to drink twice as many teaspoons to get the same result, I can’t simply compare the number of ounces in the bottle. I use the same principle when buying laundry detergent and other things where strength or quality matter.
Also, we use some products differently. When I buy a bag of apples or oranges, I don’t worry much if one bag that’s labeled “3-pounds” happens to weigh a little more than another bag with the same weight label. My family doesn’t eat their apples by weight. We eat one piece of fruit at a time, so I prefer to count how many apples are in the bag and choose the one with the most fruit. In the end, that will feed more people at my house.
It’s the same principle for things like granola bars, bagels, and other items that are individually packaged or portioned. Each person will eat just one or two at a time, so if there isn’t a noticeable difference in the size of the serving, I figure the unit price based on how many individual servings are in the package.
Bread is another food that doesn’t always follow the weight rule. I use two slices of bread to make a sandwich, regardless of how thick or wide the bread is. Therefore, I can make more sandwiches out of more slices. Yes, I’m the one holding two loaves up side-by-side or counting the slices. Try not to point and laugh the next time you see me shopping.
Figuring Unit Prices
The “unit price” of an item is simply the cost per ounce, pound, serving, etc. You figure the unit price by dividing the total cost by the number of units. Here’s an example:
A bottle of ketchup is on sale at $1.27 for 36-ounces.
$1.27 ÷ 36 = $0.035 per ounce
Comparing Unit Prices (Method 1)
The unit price of an item only helps our grocery budget if we are able to use it to purchase the best deal (or walk away from a bad one).
To compare unit prices, you can simply figure out the unit price for each product (as shown above) and see which one has a lower price per unit.
But my brain gets tired easily. I might as well just admit it. Trying to remember the unit price of the first item while figuring the unit price of the second item sometimes makes me want to cry in the ketchup isle. Well, almost.
My mental breakdown has led me to discover a little trick….
Comparing Unit Prices (Method 2)
If your brain is mushy like mine, you can try this trick: Find the unit price of the first item, then multiply it by the number of units in the second item. Here’s an example:
One bottle of ketchup is $1.27 for 36-ounces. Another bottle of ketchup is $1.54 for 42-ounces.
First, we figure the unit price for one of the bottles: $1.27 ÷ 36 = $0.035 per ounce
Then, we multiply that amount by the number of units in the second bottle: $0.035 x 54 = $1.47
So, the first bottle is the better price because if the second bottle would have been priced at the same unit cost, it would have been cheaper than the price listed ($1.54 in the is case). To prove it, let’s figure the unit price of the second bottle:
$1.54 ÷ 42 = $0.036 (See? It has a higher unit price.)
Boy, I’m confusing! Let’s do a second example using the exact calculator functions:
One can of tomatoes is $0.99 for 15-ounces. Another can is $1.39 for 28-ounces.
.99 ÷ 15 = (.066 shows on calculator) x 28 = $1.84
Since $1.84 is more than the listed price of $1.39 for the 28-ounce can, I know the price for the larger can is a good deal. basically, this figure shows that if the 28-ounce can was priced using the same unit cost as the 15-ounce can, it would be more expensive.
Does that make any sense? Any at all?
Warehouse Club Warning
Be extra careful when comparing grocery store products to warehouse club, or big box store, prices. The warehouse club regularly sells products in different units and sizes than a traditional store. Be sure you are always considering how you will use the product, rather than simply buying the item because it is cheaper per ounce.
Now that I’ve thoroughly confused you, get out there and do some math in the middle of the grocery store!
Do you figure the unit prices of the items you buy? Do you have any extra tips or tricks to share?