One good thing about HEB (the grocery store chain in Texas) is that all price labels show unit price as well. I’m constantly comparing unit prices.
You would think when something is larger that it will always be a better deal based on unit price, but I have found quite a few times where it wasn’t.
It’s also a good way to comparison shop when there are a lot of options. I do this for honey because there are so many brands on the shelf. I use quite a bit for my oatmeal, so I don’t mind buying a bigger bottle that is 10 cents an ounce (or whatever the cost is) versus buying a smaller bottle that is 18 cents an ounce.
Just be careful when buying bigger amounts. Make sure you’ll actually be able to consume all of that before it goes bad. I wouldn’t buy 5 pounds of tomatoes because I know I’d never eat them fast enough, so I’d actually be wasting money. But for things with a long shelf life it’s OK.