Aldi, Lidl, Walmart or Costco: The Cheapest Grocery Store for Meal Prep

Every "cheapest supermarket" article ends the same way: Aldi wins, go to Aldi. The rankings are real, but they are answering a question that has almost nothing to do with how a person who meal preps actually shops.

Because the cheapest store on a basket comparison is not the cheapest store for you. It depends on how much you buy at once, how fast you cook it, and whether it survives until you do. And meal prep changes all three of those at the same time.

So here is the 2026 ranking, and then the part nobody writes down: what to do with it once you cook in batches.

updated

August 2026

stores

5 compared

biggest gap

21.4%

annual saving

up to $1,284

#Which grocery store is cheapest in 2026?

Costco, by a clear margin — its average prices run about 21.4% below Walmart's, against roughly 8% for Aldi and Lidl. That gap is far larger than the one people usually argue about.

The figures come from 2026 basket comparisons in which the same list of common groceries is priced across chains nationwide. A Consumer Reports basket study put Lidl 8.5% and Aldi 8.3% below Walmart, with the regional chain WinCo 3.3% below. Separate analyses covered by Tasting Table put Costco furthest ahead of all of them.

#How these comparisons are made, and where they mislead

They price a fixed basket of identical or equivalent items at each chain, which is fair — and which quietly assumes you can buy every item at every store.

You cannot. Aldi carries roughly a tenth of the range a full supermarket does, and Costco sells almost nothing in a size that suits one person. A basket comparison prices the shop it can complete, not the shop you would really do.

That is the gap this article is about.

#How much cheaper is Aldi than Walmart, really?

About 8% on a like-for-like basket, and 10-15% on the fuller comparisons — call it $40 to $60 a month on a $500 grocery budget.

That is a genuinely good saving for a store you can be in and out of in fifteen minutes. Aldi's model is a narrow range, almost all own-brand, minimal staff, and no negotiation with suppliers over shelf position — and the saving is real rather than a loss-leader trick.

#What Aldi gives up to get there

Range, mostly. If your recipe needs fish sauce, gochujang, buttermilk or a specific cut of meat, you will be making a second trip.

For meal prep this matters less than it sounds. Batch cooking runs on maybe twenty ingredients you buy every single week — onions, garlic, tinned tomatoes, rice, beans, oats, eggs, chicken, frozen vegetables — and every one of those is in Aldi's core range.

#Is Costco actually the cheapest, or does the membership eat the saving?

The membership is trivial next to the saving. A Gold Star card costs $65 a year, and at a 21.4% price advantage it pays for itself once you have spent about $304 there.

That is a single large shop. Almost anybody who walks into a Costco more than twice a year is ahead.

#Which membership tier should you take?

#Gold Star at $65 a year

The default, and the right answer for almost everyone. At a 21.4% price advantage it clears its own cost after roughly $304 of spending — one large shop.

#Executive at $130 a year

Adds 2% cash back, so the extra $65 only comes back once you spend $3,250 a year in store, about $270 a month. Below that, as WTOP's break-even analysis lays out, the basic card is the better card.

#Why the 21% number is true and useless at the same time

Because it is a per-unit saving, and per-unit savings only exist if you use the unit.

#The six-pound chicken problem

A six-pound pack of chicken thighs at Costco is cheaper per pound than anything Aldi sells. It is also six pounds. If you are two people and it goes in the fridge, a third of it is in the bin by Friday, and your 21% saving has quietly become a 20% loss.

This is the reason most one and two-person households conclude that Costco "isn't worth it". They are right, given how they shop.

#Why meal prep changes which store is cheapest for you

Because batch cooking removes the exact failure that makes bulk buying a bad deal: the food sitting there un-cooked while the clock runs.

A meal prepper does not put six pounds of chicken in the fridge. It gets cooked the day it is bought, portioned, and half of it goes in the freezer within two hours. At that point the pack size stops being a risk and the per-unit price becomes the only number that matters.

That is the whole argument, and it flips the ranking. For someone who cooks in batches, Costco is roughly 14% cheaper than Aldi. For someone who shops daily and cooks tonight's dinner tonight, Aldi wins and Costco is a trap.

#What freezing does to the arithmetic

It converts a three-day shelf life into a three-month one, which is the difference between a bulk pack being a saving and being a gamble.

Cooked chicken keeps three to four days refrigerated and about three months frozen. That single fact is what makes a warehouse pack rational for a two-person household — and it only works if the freezing happens on shopping day, not on day three when you notice the date. Our freezer guide covers what survives and what does not.

#What should you buy at each store?

Split the list by how the store is built rather than by chasing the lowest number on every line.

#How the split works in practice

#Costco — proteins and anything that freezes

Chicken, mince, eggs, rice, oats, oil, frozen vegetables, hard cheese. Everything on that list either freezes or keeps for months unopened, which is what makes the pack size safe.

#Aldi or Lidl — produce, dairy and the weekly top-up

Small pack sizes, fast trip, and the fresh items you want to buy in the quantity you will finish. This is the weekly shop.

#Walmart — the one ingredient the others do not stock

Range, not price. Treat it as the shop you visit when a recipe needs something specific, not as the shop you build a budget around.

#Proteins are where the money is

Because protein is the most expensive line on any grocery list, and the one where pack size moves the price most.

At current national averages, dried beans deliver protein at about $1.78 per 100 g against $7.83 for ground beef — a spread I worked out from BLS average price data in our cheap weekly plan. Bulk-buying the expensive protein is where a warehouse card earns its keep; bulk-buying rice saves you pennies.

#What never justifies the bigger pack

Anything with a shelf life measured in days and no freezer route. Salad, soft herbs, bananas, avocados, fresh bread.

Buying these in warehouse quantities is the single most common way people lose money while believing they are saving it.

#Is a two-store shop worth the extra trip?

Only if the trips are on different schedules. One Costco run a month for proteins and freezer staples, plus a weekly Aldi shop for produce and dairy, is the version that survives contact with real life.

Two weekly shops is not a saving, it is a hobby. The time cost is real and most households abandon it inside a month.

#The version that actually sticks

Monthly warehouse run, weekly discounter run, and a standing rule that nothing from the warehouse goes into the fridge un-portioned.

#How much does this save in a year?

On a $6,000 grocery year — $500 a month — the gap between shopping Walmart and shopping well is roughly $1,200.

Subtract the $65 membership and the Costco route still clears $1,200. That is not a rounding error; it is a month of groceries.

#The number nobody puts in these comparisons

Waste. The USDA estimates a large share of household food is thrown away, and for most families that loss is bigger than the difference between any two supermarkets on this list.

Meal prep attacks that number directly, which is why it beats store-switching as a saving strategy — and why doing both is better than doing either.

#What this comparison cannot tell you

Which of these stores is near you. Aldi and Lidl coverage is patchy, WinCo is regional, and a 21% saving that requires a 40-minute drive is not a saving once fuel is counted.

Prices also move. These figures are August 2026 basket comparisons, and grocery inflation this year has been fast enough that any ranking has a short shelf life. What does not change is the method: rank by per-unit price on the things you buy in volume, and ignore rankings on the things you buy one of.

And none of it helps if the food is not cooked. A cheaper chicken that goes off is more expensive than a dearer one that got eaten.

#Do one warehouse run this month

Pick the two proteins you cook most, buy them in the largest pack you can portion in an hour, and get half into the freezer before you sit down. That single trip is where the $1,200 comes from — everything else on this page is bookkeeping.

If you want the session that turns a bulk pack into a week of dinners, our 90-minute Sunday plan is the order of operations.