The secrets of Costco revealed

Costco is unlike almost any other shop – a supermarket-wholesaler hybrid, with seemingly random membership rules and aisles brimming with oversized groceries. 

But should you give it a try? Here, Which? reveals some of the secrets behind this mighty American brand and offers hints and tips for getting the most out of it.

We explain what shoppers like to buy there, how they rate it for value, what's really behind its exclusive membership rules, and how to shop there even if you don't think you qualify for full membership. 

1. What do people buy at Costco? 

While Costco sells an enormous range of products, from bicycles to blenders, food and drink were the most popular items bought by non-wholesale Costco members in our survey*. 

This was followed by household products, such as laundry or cleaning items, and then alcohol. 

Costco sells both well-known brands and own-label items under the Kirkland Signature name. Lots of shoppers said they bought toilet rolls and kitchen rolls in bulk, and others praised it for its range of party food and cheap fuel prices. 

But many warned that you need freezer or storage space for buying in bulk, and others said availability was patchy.

• Find out more: best supermarket food and drink

2. What do shoppers like about Costco?

Shoppers we asked were pretty happy with Costco, with 83% saying they were either fairly or very satisfied with their shopping experience in the previous 12 months. A similar proportion (79%) rated it good for value for money. 

Costco is also in our tech and home appliance retailer surveys, where it performs decently. 

It's ranked fifth out of 19 retailers in our tech survey, with a customer score of 83%, and joint 10th out of 33 retailers in our appliance survey, where it gets 82%. 

The non-wholesale shoppers in our latest survey told us they love Costco's generous returns policies, and several mentioned the quality of its meat and fish. But others warned of limited stock, and some said prices weren’t always lower than those in conventional supermarkets. 

Their top tips? Avoid peak times, compare prices, and don’t buy what you don’t need. 

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3. How does Costco compare on price?

We checked the Costco website on a snapshot day in February. 

First, we looked at Cushelle Quilted 3-ply Longer Toilet Roll. A 32-roll pack was £19.89 online at Costco – that's 62p per roll. 

At Tesco on the same day, a 12-roll pack (the biggest it sold) of the same toilet rolls was £13.25 – that's £1.10 per roll. 

Meanwhile, at Sainsbury's, the same 12-roll pack was also £13.25, but its Nectar price was £8.50 – making it 71p per roll. 

That means Costco was the cheapest, not accounting for the membership fee. 

We also checked Yorkshire tea bags. Costco's website had 600 for £14.99, which is 2.5p per bag.

Aldi was selling a 210-bag pack for £5.79 – that's slightly more per bag, at 2.8p. At Tesco, the cheapest unit price was also 2.8p per bag, whereas at Sainsbury's, it was 3p per bag.

But at Asda, a big pack of 480 Yorkshire tea bags was £11.92 – that's the same unit price as Costco (2.5p per bag) but without the membership cost on top, showing it can pay to shop around. 

• Find out more: what's the cheapest supermarket?

4. Why does Costco have such odd membership rules? 

Only members of certain professions can shop in Costco stores. Accountants and doctors qualify, but not charity workers or plumbers, for example. 

This is due to planning rules; because it’s officially classified as a ‘membership club’ rather than a normal retailer, Costco is allowed to open in locations where other shops might not be able to – but only on condition that it restricts access by not opening to everyone. 

Annual membership costs from £42. Business owners and managers qualify for a separate trade membership, too.

5. How to get around the rules if you don't qualify 

If you don’t qualify for store membership, don’t give up hope. Anyone aged 18 and over can pay for an online membership (which also costs from £42 annually). 

You can be of any profession (or none), but you won’t be able to shop in Costco stores or its fuel stations. 

However, Costco’s website warns that the same items might be cheaper in its stores, so you might not always get the lowest price. You may also have to pay for delivery.

If you have an in-store Costco membership, you can also shop online if you prefer.

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