Grocery Shopping 101

One common trap with buying in bulk is the fact that on some products, the higher volume version often has a higher cost per unit than the smaller version. For example, I recently spied two cans of tuna on the shelf at my local grocery store. The same brand (Starkist) featured a 5 ounce can for $1.29 and a 12 ounce can for $3.19. Per ounce, the smaller can featured tuna for $0.258 per ounce, while the larger can cost $0.265 per ounce, making the smaller can the better deal. This stuck in my head, so I went home and did some research on these price differences.

This “feature” crops up in many different products is called quantity surcharge, and it’s been prevalent in the supermarket and department store since the 1970s at least. Recently, while browsing through the Journal of Consumer Affairs (seriously – I live not too far from an academic library, and JoCA has lots of interesting material in it that serves as great food for thought), I came across an older article entitled Measurement of Incidents of Quantity Surcharge Among Selected Grocery Products. The article identified ten specific products where quantity surcharges often occur.

So, without further ado…

10 Products to Study Carefully Before Buying in Bulk

I went to the store and tried to find them myself – my notes on what I found follow each item.

Tuna fish

In the article’s survey, tuna suffered from quantity surcharge 84.4% of the time. In other words, the best deal on tuna is usually the small cans, not the bigger cans, as I noticed above.


In the article’s survey, ketchup suffered from quantity surcharge 45.0% of the time. When looking for this, I observed it with Heinz ketchup. I also noticed that a ketchup multipack of smaller bottles was actually the best deal.

Canned beans

In the article’s survey, canned beans suffered from quantity surcharge 40.7% of the time. When I looked for this one, I noticed it in virtually every type of Bush’s baked beans in my local store – most other brands had almost identical prices per unit in all sizes.

Salad & cooking oil

In the article’s survey, oils suffered from quantity surcharge 36.5% of the time. This was perhaps the worst example I found. I found a store brand of olive oil in two different sizes, with the larger size costing almost 40% more per ounce than the smaller size. Even a cursory glance at the prices made it clear that the prices were out of whack.

Dishwashing detergent

In the article’s survey, dishwashing detergent suffered from quantity surcharge 34.1% of the time. I found this in the store brand of dishwashing detergent – the name brands were cheaper to buy in bulk.

Laundry detergent

In the article’s survey, laundry detergent suffered from quantity surcharge 33.3% of the time. Similarly, I found the store brands actually had a quantity surcharge, while the name brands did not.

American cheese

In the article’s survey, American cheese suffered from quantity surcharge 31.6% of the time. Yet again, the store brand seemed to do this, while the name brand did not.

Canned vegetables

In the article’s survey, canned vegetables suffered from quantity surcharge 13.0% of the time. I only found one incidence of this after examining quite a few canned vegetables, and that incidence was the result of a sale on the smaller cans.

Jams and jellies

In the article’s survey, jams and jellies suffered from quantity surcharge 12.1% of the time. I couldn’t actually find different volumes of most jams and jellies.


In the article’s survey, syrups suffered from quantity surcharge 5.2% of the time. I didn’t actually find any when I looked around.

What lessons can we learn?

The best strategy is to always calculate the cost-per-unit yourself

Or use stores that calculate it for you. Many stores give you the cost-per-unit right on the shelf. If your store does that, use the cost-per-unit as your metric for making a purchase. If your store does not, you can calculate it yourself very easily and quickly with a pocket calculator.

Sales and coupons easily make this confusing

Most of the time, sales alter the picture, but not always in the obvious way. I saw several incidences of the large and small versions both being on sale, where the regular prices had the smaller version being a better deal and the sale prices had the larger version being a better deal. This wasn’t clear, either, since the “sale” tags didn’t have the price per unit on it. Again, it pays to be able to calculate it yourself.

Store brands seem to do it more often than name brands

This might just be a quirk of my observations, but I consistently found quantity surcharges more often in store brands than in name brands.

Multi-packs were usually the best deal

Multi-packs of the smaller version of most items was the best deal overall – but it does require you to do things like buy three bottles of ketchup or dish soap at once.

Warehouse stores add to the confusion

I tried doing price comparisons between my local warehouse store (a Sam’s Club) and my preferred grocery store. I found that on almost every item I compared, the warehouse club was cheaper per unit than the same brand at the grocery store. However, the brands carried at each were often vastly different, so it’s hard to get a full picture.

In the end, though, the key is to just focus on the cost per unit. The larger item is usually the best deal, but as you’ve seen above, it’s not the best deal often enough that it’s well worth your time (and money) to pay attention when shopping.

Good luck!

Trent Hamm
Trent Hamm
Founder of The Simple Dollar

Trent Hamm founded The Simple Dollar in 2006 after developing innovative financial strategies to get out of debt. Since then, he’s written three books (published by Simon & Schuster and Financial Times Press), contributed to Business Insider, US News & World Report, Yahoo Finance, and Lifehacker, and been featured in The New York Times, TIME, Forbes, The Guardian, and elsewhere.

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