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Supermarket Savings Tip #3: Bring a Calculator With You When You Shop

One simple way to save money on your grocery bill is to always bring a calculator with you when you shop. I’ve done this for years and it’s been a huge help.

Why You Should Always Shop With a Calculator

1. You can keep a running total to make sure you’re not going over budget.

Since I use cash when I shop, it’s important to keep a tally of how much I’ve spent so far so that I don’t get up to the register and not have enough money to pay for my groceries. Keeping a running total also encourages me to carefully evaluate all purchases as I put them into my cart–and it helps ward off the temptation to make impulse purchases on things I don’t really need to buy.

2. You can easily compare the cost per ounce.

Some grocery stores have the cost per ounce right on the price tag, but many stores don’t. This is when a calculator is your best friend. Instead of trying to stand there and work out the equations in your head or scratch them out with a pen on your grocery list, whip out your calculator and you can quickly figure out which product is a better deal to purchase.

3. You can quickly tell if you were incorrectly charged at checkout.

I can’t tell you how many times I’ve been overcharged at the checkout lane because something didn’t ring up right, they didn’t scan all of my coupons, or my coupons didn’t deduct the right amount. If you keep a running total of how much you’ve spent, you’ll instinctively know if something’s amiss at checkout and you can immediately check the receipt to figure out the issue and get it corrected.

Do you use a calculator when you shop?

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  • Kaylee says:

    I always use a calculator (on my phone) when I shop. It helps me see if my total is getting too high and if I need to reevaluate what I am putting in my cart. It also lets me double check to see if a surprise sale or clearance item works out to be a good deal after coupons so I can make sure I am not wasting my money on an impulse buy : )

  • NaDell says:

    I keep a tally on my grocery list of the four 1111’s and then across to keep track. I think it takes less time and I already have my pen to cross out things on the list anyway, so I might as well write that quickly. It works very well, I think.

  • Amanda says:

    No, but I keep a total in my head, especially when shopping at a place like Fresh & Easy, where you need a minimum to use their coupons. It’s one of the times that being arithmomanic is actually helpful in everyday life. I do sometime use my phone to do the math on unit prices, though.

  • Jessica says:

    I also use a calculator, but I round everything up to the nearest dollar amount, so if something is $2.75 I put it in as $3, if it’s $3.30 I put it in as $4. Rounding up and making sure I stay within my budget always makes for extra money when I leave the store.

  • I do not use a calculator when I shop. Because I would need a third arm to keep the list, the kids, and the calculator all under control.

    It’s a good idea, though. Once the kids are older I’ll probably switch back from the “running total in my head” approach.

    • You’re doing better than me! I can’t even keep a running total in my head because either the baby is crying or my other kids are fighting with each other. I can’t wait until the day where grocery shopping will be my peaceful “me” time again!

    • Susan E. says:

      So true, so true! I wish I could use the calculator but the kids fight over playing with it! I guess I should bring 3 calculators. If they are behaving well, sometimes I will keep a running total on a piece of paper. But that doesn’t happen often. Our time will come…someday…I hope!

  • Lorelei says:

    I feel a calculator is a must when grocery shopping! In addition to all the reasons above, I have found that entering a product’s price into the calculator helps you remember that price. So, if later, you find a good deal on an item and you want to swap it for something already in your cart or just need to trim down your cart to make your budget, you can simply glance at what you have so far and determine what can go. Another tip that has helped me a lot is to save your receipts for the past 3-4 months and have them handy when you make your list. That way you know your approximate total before you even get to the store, which helps me determine just how strong my tunnel vision needs to be when avoiding those impulse buys.

  • Catherine says:

    I domt add, I subtract. I put the amount of cash I have into my calculator and then as I add its to my cart, I subtract (always rounding up). This way I can see how much I have left as I go through and get my items.

    • Catherine says:

      Also, I get the variable price items first, then the fixed price items – produce, deli counter first, then cereal, bread, milk, etc. so I can always skip a box of cereal if the apples were a bit more per lb than I had planned.

    • Lee says:

      That is smart. I never thought of that. Last week I went over my budget by $5 and I could tell adding up, but it would have hurt more had I seem negative numbers and I would have probably put something back. 🙂

    • Amy says:

      Definitely a subtractor…seeing how much I have left always helps when making decisions on what to get.

    • Wendy says:

      What a great idea! I will have to try this.

  • Victoria says:

    I forgot mine when I was shopping yesterday and I really missed it.

  • Lee says:

    I don’t always bring my calculator, but I just recently made the switch to cash and it is becoming more important.

  • Carla says:

    I think I will start doing this because trying to do things in my head is not the best way to do it!
    Thanks for this latest of your posts.

  • Bethann says:

    I always use the calculator on my phone, and I was recently “told off” by a very irate lady who thought I was ‘texting’ all the way through the store. Oh, dear!

  • Meredith says:

    I know a lot of people advise against bringing a spouse but I bring my husband (and daughter) believe it or not. He’s a cost analyst and it like having a human calculator with me. By the time I figure it out myself, cost per unit/best deal, it’s been too long. He drastically shortens the process and I spend less. So I guess my advice is to marry a financial analyst! Ha.

  • Cindy says:

    I might add, make that a real calculator, not your phone calculator. They are simply not easy enough to use in the hustle and bustle of the grocery store, especially if you have a smartphone. Funny how those touchscreens get touched so often and you lose your work. 😉

    • carole says:

      i agree!! i love my smartphone for just about everything EXCEPT trying to calculate in the store!! :-=)
      i’m gonna start doing the subtracting thing- that will work much better for me. thanks for the tip!!

  • Jan says:

    I always used a written list in the past (categorized loosely by aisle) (because I’m OCD sometimes) 😀 and would keep a running, rounded-up total off to the side of it as I checked off each item. I’ve recently been experimenting with the shopping list on the Cozi app (LOVE it!) and have noticed I’ve been spending more than I planned each trip. Reading this just made it dawn on me – I need a way to keep that running total again! I’m glad you post the basics like this, as good reminders to keep doing the things that work, when we change techniques!

  • Elizabeth says:

    I’ve always kept a calculator to figure cost per ounce and that kind of thing and just written tally marks on my list for a running total, but I’ve recently found that keeping that running total on my calculator keeps me much more accurate. Also, don’t forget to add the tax! (to those things that are taxable)

  • Krystal says:

    I always use the rounding up idea too, it usually covers what I will be using in tax too. Since I always have my four kids with me, I have the oldest help add it up and make it a game for the younger ones to try to remember the number. At the end of the aisle I ask “What are we at?!” It helps keep them occupied and helps with their math skills. But honestly it’s to keep my head on straight! 😉

  • I don’t carry a calculator but I do remember the prices (or rough pricing) and will stop and add things up during diff parts of the store. I also add them up in my head while placing them on the conveyor belt at the checkout. My husband thinks it’s crazy I can remember it but it saves us a ton of money and then I have a rough estimate to know if something didn’t ring up correctly!


    • Andrea says:

      I do this, too.

      Also, before I leave for the store, I make an estimate of how much my shopping trip “should” cost.

      I typically don’t bother with a calculator, because using my brain is good mental exercise.

  • Katheryn F. says:

    I notice that when I use my calculator shopping I truly am more careful. If I forget my calculator, well, my cart is definitely filled with more frivolous things. So, yes, using a calculator is so helpful in monitoring what goes in because you can always see where you are at and if its worth the extra.

  • Lis says:

    If something rings up wrong, I have found that it is easier if you bring it to their attention BEFORE you finish checking out rather than after. It just seems to take less time and eliminates standing in line at customer service. But you need to know how much your total should come to.

  • Marlana says:

    Nope, I don’t. But I do add up the groceries as I go in my head (the currency where I live is easier to add up than the dollar because we don’t break things up as low as a penny), and my kids are always amazed that I’m never farther than $3 off.

  • MK Jorgenson says:

    It used to drive me crazy that my mom carried around a pen and paper and made little tally marks as she went through the grocery store (because, obviously, everybody was watching every move we made and judging me based upon my mother’s actions…or so go the thoughts of every tween and teen ;))…and now I do the same thing!

    And really, since my list is made ahead of time, I know about what I’m going to spend before I leave home. But I do pull out my phone to use the calculator if I think I’ve found a good, unexpected deal and need to do a little ounce-for-ounce math.

  • Emilie says:

    I shop mostly from the ads and so I write the prices on the side of my list. I know roughly ahead of time how much it should be. I canthen add in something nto lsited if something I wanted is out of stock and stay within by cash amount.

  • tracy says:

    I have noticed that some stores and/or corporations have realized we assume things are cheaper when they’re a larger size, and they use that assumption against consumers and sometimes actually make the per-ounce price more for a larger size. I definitely notice that with toothpaste. And it can be maddening to figure out comparison prices; with paper towels I resort to looking at the total square footage when trying to figure out which package (double rolls! supersized rolls! six actually equals eight) to choose.

    • Jessica says:

      Oh, that’s my current pet peeve with papertowels and toilet paper. There seems to be an imaginary roll they keep comparing it too! Also things that just are labeled as 13 for $9 or some other ridiculous number.

  • Charissa says:

    Our local Stop and Shops have the hand-held scanners. I use those primarily b/c I can keep a running total.

  • Kara M says:

    I believe that using a calculator is one of the main reasons my grocery budget is able to stay so low. It’s a HUGE help and I can’t imagine going through the store without one now. I will have to say my husband was horrified when he went to the grocery store recently with me–I told him to just get over it.

  • CJ says:

    I use a solar calculator at the grocery which works great during the day when the store is well lit. But I’ve found it doesnt work in the aisles if I shop late at night – my store must dim the lights at night. I bet I looked strange on a recent late night trip as I kept having to walk to the back of the store where the lights were brighter in order to use my calculator!

  • Lori says:

    Just had to comment on the photo – I’m not a vegetarian but the thought of putting your wallet or your hand-held calculator on packages of raw meat – yucko. It may seem wasteful, but I always use the clear bags at the meat dept. to wrap the clear-packaged meat in (two per bag, back to back for easy check out scanning) to prevent any gross spills from packaging leaks, etc.

    • Heather says:

      I used to work as a cashier at a grocery store, and I loved it when customers did that! You don’t want blood all over your groceries, but the cashiers don’t want it all over their hands and work area. On particularly bloody things, you can try double-bagging them, with the bags opening in opposite directions. I always use the bags, too.

      Monitoring the items as they ring up also helps. If you know what the prices for your items are, you can catch things right away, and the cashier can often fix it. They don’t know all the prices for every item in the store, and they’re usually too focused on getting everything scanned quickly to be able to pay that much attention to the prices as they ring up anyways.

  • Liz says:

    I use a calculator when I shop. I have noticed that often on the price tags, there will be a cost per ounce/item/unit. But it doesn’t always have the same measure even on similar items…I was at Sam’s Club recently and needing facial tissue…one of the price tags listed the cost per tissue, but another listed the cost per box. So keeping a calculator handy makes it very convenient for me to make sure I’m getting the best deal.

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