How Costco Built the Membership Flywheel

1.The Original Problem Was Retail Economics

A traditional retailer has to earn enough gross profit from merchandise to pay for stores, labor, logistics, advertising, shrink, corporate overhead and capital investment.

That often creates pressure to raise merchandise margins.

The membership warehouse model changes the equation.

Members pay an annual fee before making most of their purchases.

Costco can therefore earn part of its economics outside the markup on each item.

In fiscal 2025 Costco reported:

Net sales
$269.912B

Merchandise gross margin
$30.026B

Membership fees
$5.323B

Costco's merchandise gross margin percentage was only 11.12%. [S1]

The point is not that membership fees replace merchandise economics.

They do not.

The point is that recurring membership revenue gives Costco more room to treat low merchandise prices as a strategic tool rather than requiring every product category to carry a conventional retail margin.

2.Membership Changes What "Customer Value" Means

A Costco member has already paid for access.

That creates an unusual burden on the retailer:

The member must repeatedly feel that the annual fee was worth paying.

This is why Costco's membership documents connect fees and low prices.

When Costco raised U.S. and Canada membership fees in September 2024, it said membership fees help offset operating costs and support the company's ability to keep prices low. [S8]

That creates a circular relationship.

member pays fee
↓
Costco must create visible value
↓
low prices make fee feel worthwhile
↓
member shops more
↓
renewal becomes more likely

Membership is therefore both a revenue source and a promise about value.

3.Low Prices Create Volume

Costco's FY2025 filing describes its model as selling a limited selection of nationally branded and private-label products at low prices to produce high sales volumes and rapid inventory turnover. [S1]

That logic matters.

A retailer can make money in two broad ways:

higher margin × lower volume

or:

lower margin × much higher volume

Costco is deliberately built around the second direction.

Low prices can increase purchase frequency, basket size, traffic and unit volume.

That volume becomes useful in the next stage of the flywheel.

4.Volume Concentrates Buying Power

Costco does not try to carry every version of every product.

Its core warehouses generally carry fewer than 4,000 active SKUs. [S1]

That means demand is concentrated.

Imagine two retailers each sell the same total number of bottles of detergent.

One spreads those sales across 40 options.

The other spreads them across 8.

The second retailer can place larger orders behind each winning item.

That can strengthen supplier negotiations, production planning, freight efficiency and inventory productivity.

The model becomes:

fewer items
↓
more volume per item
↓
stronger buying economics
↓
lower unit cost
↓
lower member price

Membership does not create buying power by itself.

Member demand combined with limited assortment does.

5.Limited Assortment Also Reduces Operating Complexity

The SKU model affects more than procurement.

Fewer items can mean simpler receiving, less shelf management, less merchandising complexity, higher sales per SKU and faster inventory movement.

Costco reinforces that with a no-frills warehouse format.

Products can arrive on pallets or in manufacturer shipping cartons and move quickly to the sales floor.

The company also uses cross-docking depots to move some merchandise through the distribution system without holding it for long periods. [S1]

That helps keep handling costs low.

The store is designed around product movement more than elaborate presentation.

6.Rapid Turnover Changes Working-Capital Economics

Costco's filing says its high sales volume and rapid inventory turnover can allow it to sell inventory and receive cash before it is required to pay some merchandise vendors. [S1]

This is a subtle but important part of the model.

In a slow-turn business:

buy inventory
↓
cash leaves
↓
inventory waits
↓
customer buys later

In a faster-turn business:

inventory arrives
↓
customer buys quickly
↓
cash is received
↓
supplier payment may come later

When that happens consistently, inventory can consume less working capital than a casual observer would expect from such a large retail operation.

Rapid turnover therefore supports low prices in two ways:

1. it reduces the cost of holding merchandise; 2. it can improve cash-flow timing.

7.The Warehouse Format Protects the Cost Structure

The membership flywheel would weaken if the retailer spent the savings somewhere else.

Costco therefore historically emphasized large warehouse buildings, palletized merchandise, limited decor, little traditional advertising, a relatively narrow assortment and operational simplicity.

Jim Sinegal described the early philosophy in terms of eliminating conventional retail costs such as fancy displays and sales overhead while running a tight operation. [S18]

The economic logic is:

low prices only work
if
low prices are matched by low operating cost

A low-margin retailer with a high-cost structure has little room for error.

8.Membership Renewal Is the Scorecard

A subscription business can report membership growth even if customers quietly become dissatisfied.

Costco therefore watches renewal.

At the end of fiscal 2025, renewal rates were:

U.S. and Canada
92.3%

Worldwide
89.8%

In Q3 fiscal 2026 they remained:

U.S. and Canada
92.2%

Worldwide
89.7%

[S1][S4]

Renewal is important because it compresses many questions into one behavior:

Did members find enough value?
Did they shop often enough?
Did they save enough?
Did they trust the assortment?
Was the warehouse convenient enough?

A high renewal rate does not prove every member is equally satisfied.

But it is one of the clearest signals that the overall value proposition remains durable.

9.Executive Membership Deepens the Loop

Costco Membership includes an Executive tier.

An Executive member pays more but can earn a 2% reward on qualifying purchases, up to an annual cap. [S7][S9]

The commercial mechanism is:

higher annual fee
↓
2% reward
↓
more incentive to consolidate spending at Costco
↓
higher Costco sales
↓
reward becomes more valuable
↓
renewal / continued use

By Q3 fiscal 2026 Costco reported:

Executive memberships
41.2M

Executive sales penetration
75.0%

[S4]

That does not mean the reward causes all of that spending.

Executive members are also likely to be Costco's more engaged shoppers.

But the product is clearly designed to reinforce spending concentration.

10.Gas Extends the Membership Habit

Costco Gas is a useful example of a lower-margin business that can strengthen the whole membership proposition.

Costco says gasoline carries lower margins than much of its merchandise business, but gas stations can increase warehouse traffic. [S1]

The flywheel becomes:

member wants low-cost gasoline
↓
visits Costco property
↓
membership feels more useful
↓
may combine gas + warehouse trip
↓
more Costco spending

Gas is therefore not best understood as an isolated convenience-store business.

It is part of membership utility.

11.Kirkland Signature Reinforces Price Credibility

Kirkland Signature adds another layer.

Costco says Kirkland products are generally priced lower than national brands and generally earn higher margins than national-brand merchandise. [S1]

That can create a useful combination:

member gets lower price
+
Costco gets attractive merchandise economics
+
product is exclusive to Costco

The product therefore strengthens both membership value and retailer differentiation.

A national brand can be sold by multiple retailers.

Kirkland Signature cannot.

12.Travel, Business Services and Other Ancillaries Make the Fee Easier to Justify

A membership becomes more defensible when it creates value across more categories.

Costco extends the membership into travel, gasoline, optical, hearing aids, pharmacy in relevant markets, Business Centers, e-commerce and delivery.

Costco Travel is especially revealing.

A warehouse club does not need to sell vacations to operate a grocery business.

But travel gives members another reason to think:

"I get more value from this membership than warehouse access alone."

That makes ancillary services part of retention economics.

13.The Flywheel Also Disciplines Costco

Membership creates recurring revenue, but it creates a constraint too.

If Costco were to maximize short-term product markups aggressively, it could weaken the reason members pay the fee.

The company's 10-K says management believes members are attracted by the availability of quality merchandise at consistently lower prices and that the membership format is integral to profitability. [S1]

That creates tension:

raise merchandise margin
→ more profit per sale today

but possibly
→ weaker price reputation
→ lower member value
→ weaker renewal / traffic tomorrow

The membership model therefore makes long-term price credibility economically important.

14.Why Costco Does Not Need to Maximize Membership Fees Either

The same logic applies to the annual fee.

A company with high renewal rates could theoretically push prices harder.

But membership itself is the gateway to merchandise volume.

If the fee rises too aggressively:

membership friction rises
↓
fewer / less engaged members
↓
less warehouse volume
↓
weaker buying concentration
↓
less purchasing advantage

Costco has historically raised fees infrequently rather than treating membership as a subscription whose price should be optimized every year.

The September 2024 increase was the first U.S./Canada fee increase since 2017. [S8]

15.The Flywheel Is More Than a Loyalty Program

Many retailers have loyalty cards.

Costco's model is structurally different because shopping access itself is tied to paid membership for most warehouse purchases.

That changes customer selection, economics, pricing, renewal behavior and purchasing frequency.

A loyalty program sits on top of a retail business.

At Costco, membership is inside the business model.

16.What Could Break the Flywheel?

A flywheel is not automatic.

Several things could weaken it.

Prices stop feeling special

If members can routinely find better value elsewhere, the fee becomes harder to justify.

Assortment becomes too narrow

Limited selection creates concentration benefits, but Costco still has to choose items members actually want.

Suppliers lose interest

High volume is attractive only if supplier economics remain acceptable.

Warehouse experience deteriorates

Crowding, checkout friction or stockouts can reduce member satisfaction.

Digital convenience falls behind

Members increasingly compare Costco with delivery and omnichannel retailers, not only physical stores.

Regulation or cost inflation changes ancillary economics

Gas, pharmacy, payments and other services have their own operating constraints.

The model works because several pieces stay aligned.