Do the math: unit price − waste + storage/time; keep your target unit prices on your phone for quick retrieval
Bulk wins: paper goods, trash bags, laundry/dish tabs, AA/AAA, cheese/meat if you freeze, coffee you’ll finish in 6–8 weeks
Buy small on promos: condiments, cereal, pasta/sauce, spices, snack packs, short-fuse produce, bread (unless you freeze), brand-name drinks; follow finish windows (berries 2–4d, deli 3–5d, oils 4–6mo)
If you’ve ever tossed a 16-count package of guacamole in your cart and thought, “This is definitely cheaper… right?”, this one’s for you. Warehouse math isn’t just about unit price, you need to factor in unit price minus waste, plus storage space, plus time, minus any coupons or loss-leaders you’d grab at a regular grocery store. Do the math wrong and your “deal” turns into a science experiment in the back of the fridge.
Here’s a no-nonsense playbook: 8 items where bulk wins at Costco/Sam’s, and 8 items that are usually better as non-bulk buys with grocery coupons or weekly ads.
First, the quick “warehouse math” rules
Be sure to start with the unit price (price ÷ ounces/sheets/loads) and use that as your baseline. Then adjust for your reality. Meaning what you’ll use before it spoils, the storage it takes up, and the time you save by making fewer trips.
And always keep in mind that coupons and loss-leaders (pasta, cereal, condiments) can often beat warehouse pricing when buying smaller packs.
Pro tip: write down the target unit price on your phone for the top 20 products you always buy. Then when you see it below the target, you buy it, regardless of the store.
8 bulk buys that usually win at Costco/Sam’s
1. Toilet paper & paper towels
A giant pack equals a lower cost per 100 sheets/square feet, and zero spoilage. Which means as long as you keep it dry, you’ll use it and save money.
Math cue: Compare cost per 100 sheets (TP) or per sq ft (towels). Warehouse pricing almost always beats grocery store “sale” pricing over a month.
2. Trash bags
With the Kirkland and Member’s Mark brand you’re getting the same (or better) brand-level quality for less per bag, thicker plastic that’s less likely to poke/tear, and enough on hand that you’re not doing the “last bag” panic.
Math cue: Compare cost per bag on the size you actually use (13-gal kitchen or 30–33-gal outdoor). Example: 200-ct box for $22 = $0.11/bag; grocery 45-ct for $8 = $0.18/bag which equates to about 40% more
3. Laundry detergent (pods or big jugs)
Club sizes bring Kirkland/Member’s Mark down to rock-bottom ¢/load, so one purchase covers months without emergency restocks at a very competitive price.
Watch-out: Don’t buy a scented variety that you’re unsure of in a 2-gallon drum. Try a small bottle first before you go all in.
4. Dishwasher detergent tab
Cost per tab plunges at the warehouse. Plus, dishwasher tabs store forever and won’t spill.
Math cue: Price ÷ tab count. Easy win.
5. Batteries (AA/AAA)
Crazy high unit savings, especially when you buy Kirkland or Member’s Mark, plus they still have a long shelf life. The Costco CEO even revealed that Duracell makes Kirkland batteries so you know the quality is good.
Pro tip: Store a sleeve in a Ziploc bag in a cool spot to keep them fresh.
6. Cheese blocks & shredded (if you freeze)
Cheese from Costco and Sam's wins on unit price, and most firm/semi-hard cheeses (cheddar, low-moisture Mozzarella, Jack, Colby, provolone, Parm) freeze well so waste won’t be an issue. I recommend portioning or pre-shredding before freezing and use straight from frozen for hot dishes.
Math cue: Buy a 2-lb block, shred half, freeze in flat bags. No waste = true savings.
7. Meat in value packs (when you portion + freeze)
Warehouse meats often win on price per pound, and you get to control the cuts and serving sizes. I’m a huge fan of splitting big packs into meal-size portions, press flat, label, and freeze.
Pro tip: Skip the “enhanced” chicken (you’re paying for brine), factor in trim/bones for true $/lb, and thaw in the fridge or cold water for easy weeknight meals.
8. Coffee beans/grounds
Coffee from warehouse clubs typically wins on cents-per-ounce, with solid house and national brands. Buy what you’ll drink in 6–8 weeks (or portion and freeze).
Watch-out: I recommend buying whole bean and grind as you go as pre-ground stales quickly once the bag has been open.
8 things to skip at the warehouse (buy smaller with coupons/weekly sales)
1. Condiments (ketchup, mayo, mustard) you use slowly
Why grocery wins: You’ll find frequent BOGO/coupons at most supermarkets that undercuts the warehouse club price. Not to mention that the jumbo tub may expire before you finish it.
Rule: If it takes you 6+ months to finish, buy smaller.
2. Cold cereal
Grocery stores beat the warehouse on most cold cereal because they run constant promos like digital coupons, BOGOs, and “mix & match” deals. These drive the unit price way down on, especially on family-sized boxes.
Math cue: Warehouse is fine for in-house brands, but flashy name brands often go cheaper at Kroger, Publix, Winco, and Grocery Outlet on promo.
3. Pasta & pasta sauce
Grocery stores treat pasta and mainstream sauces as classic loss leaders, so weekly promos and digital coupons often push unit prices well below what you’ll see at Costco or Sam’s Club.
Strategy: Stack a store sale with a manufacturer coupon and beat warehouse per-unit easily.
4. Spices you use once a month
Big jars of spices lose potency before you’re halfway through.
Buy: Smaller bottles on sale, or hit the ethnic aisle/bulk bins for even more savings.
5. Snack variety packs for picky families
At warehouse clubs, you end up paying for a bigger assortment of snacks like chips or cookies, then half of the flavors end up not getting eaten.
Buy: Focus on the smaller sale boxes of the specific flavor your kids will actually eat.
6. Fresh produce with a short shelf-life
Things like berries and spring mix lettuce spoil quickly, so if you buy the larger Costco size they often spoil before you can finish them.
Rule: If you can’t eat it in 3–4 days, buy the grocery-size on sale and restock more often.
7. Bread and buns (unless you freeze)
Mold happens. Grocery stores run weekly deals and bakery markdowns that often make more sense unless you have the freezer space.
Do this: If you do end up buying bread in bulk, keep a few days’ worth, then freeze the rest in a zip bag with the air pressed out. Then periodically take out what you need and the rest will last for 2-3 months in the freezer.
8. Soda, sparkling water, and brand-name beverages
Grocery chains treat beverages like a weekly foot-traffic magnet.
Math cue: Watch for “4 for $12” or “Buy 2, get 2” style promos that easily beat warehouse per-can prices.
How to make the math brain-dead simple
I’m a big fan of setting “finish windows” which is how long it usually takes my family to finish a product.
Quick freshness rules (buy only what you’ll finish in this window):
- Milk: 5–7 days after opening. Yogurt: 1–2 weeks. Deli meat: 3–5 days.
- Produce: berries 2–4 days, leafy greens 3–5 days, hardy vegetables (carrots/onions) 1–2 weeks.
- Cheese: soft cheese 1 week after opening; shredded 1–2 weeks; hard/block 3–4 weeks.
- Pantry staples: about 60–90 days once opened. Oils: 4–6 months (with cool, dark storage).
If you won’t finish it in that time window, and freezing is not an option, don’t buy it in bulk.