The bulk purchase of an item can save a lot of money but it can cost you a bundle if you don’t establish a handful of sensible principles. If you stick to the following steps, you can save significant money with a bulk purchase.

1. Price-per-unit is king. Calculate cost per unit which requires you to figure out how many units you would actually be buying. Then take the total cost of your purchase and divide that by the number of units.

2. Never bulk buy an item you haven’t tried before. I’ve bought trash bags where the bottom has ripped out of nearly every other bag. I’ve bought hand soap that didn’t lather. Don’t waste your time bulk buying an item unless you know that it works for your needs.

3. Never bulk buy perishable goods unless you’re going to go home and process all of it immediately. The problem is even if you save 50 or 75 percent off of the item, if you don’t use a significant portion, you’re not saving money.

4. Stack coupons and sales when bulk buying. The best time to bulk buy is when you can stack coupons on top of a bulk purchase. If I happen to notice a particularly good coupon, I’ll print several copies, then hold them until there’s a sale. Most stores will work with you on this if the sale doesn’t have a limit.

5. Ensure you have adequate storage space before you buy. If you’re thinking of buying something in bulk, make sure you have storage space before you make that purchase.

6. Don’t bulk buy everything at once unless you have an enormous bankroll. You do not want to start off by heading to the store and dropping several hundred dollars if you don’t have it in hand. Don’t do it all at once unless you have that cash easily available or you undo the financial advantages of bulk buying.

7. Split up bulk buys with friends and family. A final tip: if you see a really big bulk purchase that could save you a lot of money – like a 50 pound bag of rice or something like that, talk to some friends. If you can get three friends to split that huge bag of rice, you’ll each wind up with 12.5 pounds of rice, which is much more tolerable, plus three of your friends get the same discount.