Sales are up 20% this quarter. That sounds like good news.
But before concluding that Marketing is working better or that the Sales strategy is succeeding, there is a more useful question:

Where did that 20% growth actually come from?

Perhaps more first-time customers entered the business.
Perhaps existing customers returned.
Perhaps the same customers purchased more often.
Or perhaps the customer base did not grow at all and Average Order Value increased because pricing or Product Mix changed.
Each type of growth suggests a different business action. That is why decomposing Sales Growth is more useful than looking at the top-line percentage alone.

Sales growth does not always mean the same type of growth

Short answer: break Sales Growth into customer volume, purchase frequency and value per purchase.

At a simple level, Revenue can be understood through: Customers × Purchase Frequency × Value per Purchase

Where customer-level data is available, the business can then ask:

• Are we acquiring more New Customers?
• Are previous customers coming back?
• Are customers purchasing more frequently?
• Is each Order becoming more valuable?

This is the basic idea behind Growth Decomposition: breaking overall Revenue into components that help explain where growth is coming from. The goal is not to create a complicated formula. It is to identify where the business should act next.

1. Are you acquiring more New Customers?

Start with New Customers - people making their first purchase during the period. Shopify distinguishes First-time Customers from Returning Customers based on whether a customer already has previous order history.
If Revenue increases alongside a substantial rise in New Customers, part of the growth is likely acquisition-led.
But a rise in New Customers does not automatically mean acquisition performance has improved.

Ask:

• How much did it cost to acquire them?
• What was their first-order AOV?
• What was the Margin on the first purchase?
• Did they return for another purchase?

A business can acquire more customers while Customer Acquisition Cost rises enough to weaken the economics of that growth.
‍What this metric tells you: Are more people making a first purchase?
‍What it does not tell you: Whether those customers are profitable or likely to return.

2. Are more previous customers returning?

The second driver is Returning Customers - customers with an existing purchase history who buy again during the period. If Returning Customers rise alongside Revenue, the existing customer base may be contributing more to growth.
One distinction matters:

Returning Customer does not automatically mean Loyal Customer.

A customer may return because of a promotion, convenience, category purchase cycles or limited alternatives.
For a stronger view of retention, consider additional measures such as:

• Repeat Purchase Rate
• Retention Rate
• Time to Second Purchase
• Revenue from Returning Customers
• Customer Cohorts

Shopify separately reports First-time vs. Returning Customer Sales and Repeat Purchase Rate. Repeat Purchase Rate measures the proportion of customers who make more than one purchase.
‍What this metric tells you: Is more Revenue coming from people who have purchased before?

3. Are existing customers purchasing more frequently?

Returning Customer count and Purchase Frequency are not the same thing. Suppose you had 1,000 Returning Customers last year who purchased twice on average. This year you still have 1,000 Returning Customers, but they purchase three times on average. Your customer count has not increased, yet Revenue can grow through Frequency Expansion. Salesforce reports Average Purchase Frequency as a separate customer metric representing average Orders per customer.

A basic calculation is: Purchase Frequency = Number of Orders ÷ Number of Customers

You can also calculate it specifically for Returning Customers when analysing the existing customer base.
Example:

Period A: 1,000 customers × 2 Orders
Period B: 1,000 customers × 2.5 Orders

The growth is not coming from a larger customer base. It is coming from customers purchasing more often.

4. Or are customers simply spending more per Order?

Another common growth driver is Average Order Value (AOV).
AOV is calculated as: Average Order Value = Revenue ÷ Number of Orders

If customer count and Orders remain unchanged while AOV increases from THB 500 to THB 600, Revenue can still grow.
AOV can rise for several reasons:

• Higher prices
• More units per Order
• Upselling or Cross-selling
• Product Mix changes
• Customers choosing higher-value products
• Bundles or Promotion structure

A higher AOV therefore does not explain the cause by itself. If AOV rises because prices increase while Order volume falls, Sales and Margin should be examined together before concluding that the change is positive.

What this metric tells you: Is each Transaction generating more Revenue?

Example: Three businesses grow sales by 20% - for completely different reasons

Consider three businesses that each report 20% Sales Growth.

Business A: Acquisition-led growth

New Customers +35%
Returning Customers →
Purchase Frequency →
AOV →

The business is largely growing through Customer Acquisition.
The next question should be: What does it cost to acquire those customers, and what is their quality?

Business B: Existing-customer growth

New Customers →
Returning Customers +20%
Purchase Frequency +10%
AOV →

The existing customer base is contributing more Revenue.
The next question should be: Which customer Cohorts are returning, and what is associated with that behaviour?

Business C: AOV-led growth

New Customers →
Returning Customers →
Purchase Frequency →
AOV +20%

Sales grew by the same percentage, but through Spend per Transaction.
The next question should be: Did AOV increase because of price, Product Mix or units per basket?

What should Marketing and Sales do with this information?

The action should depend on the driver.

If growth comes from New Customers

Examine:

• Acquisition Channel
• Conversion Rate
• Customer Acquisition Cost
• First-order Margin
• Second-purchase Rate

The goal is not simply to acquire more customers. It is to determine whether those customers produce attractive economics.

If growth comes from Returning Customers

Examine:

• Repeat Purchase Rate
• Customer Cohorts
• Repurchase patterns
• Time to Second Purchase
• Returning Customer Revenue

The question may shift from “How do we acquire more?” to “How do we preserve and expand value from the existing base?”

If growth comes from Purchase Frequency

Identify which Segments are purchasing more often, which products are involved, and whether the pattern persists beyond temporary Promotions.

If growth comes from AOV

Break the change into:
Price
Units per Order
Product Mix
Upsell / Cross-sell
Promotion structure

Do not interpret higher AOV as higher Customer Value automatically.

A simple Monthly Growth Review table

You do not need a sophisticated dashboard to begin.

Then add one more field:
‍“What explains the change?”
‍This distinction matters. Metrics tell you what changed. Additional evidence is usually required to explain why it changed.

One important limitation: Growth decomposition depends on reliable Customer IDs

To separate New and Returning Customers, the business needs a reasonably reliable way to recognise the same customer across Transactions.
Problems arise when:

• Offline and Online customer records are not connected
• Customers use different email addresses or phone numbers
• Guest Checkout prevents identification
• Different systems use different definitions of “New Customer”
• Comparison periods are inconsistent

For example, someone who has purchased in-store before but shops online for the first time may be classified by the Online platform as a New Customer—even though they are not new to the business. Before analysing Growth, define Customer, Time Period and Data Source consistently.

What Growth Decomposition can and cannot tell you

Growth Decomposition can show:

• Whether Revenue is growing through a larger customer base
• Whether New or Returning Customers contribute more
• Whether customers are purchasing more frequently
• Whether AOV is increasing

It does not automatically tell you:

• Which Campaign caused the growth
• Why customers returned
• Whether customers became more satisfied or loyal
• Whether the growth will continue
• Whether the growth is profitable

Answering those questions may require additional evidence such as Marketing Attribution, Customer Research, Cohort Analysis, Margin Analysis or controlled Experiments.

The takeaway: Before celebrating Sales Growth, find out where the growth came from

Knowing that Sales increased by 15% or 20% is useful. It is not enough for a good decision.
Ask next:

Did we acquire more New Customers?
Did more existing customers return?
Did customers purchase more frequently?
Did Average Order Value increase?
And did the additional Revenue generate attractive Margin?

Acquisition-led growth requires one response.
Returning-customer growth requires another.
Frequency-led and AOV-led growth require different analysis again.
So instead of ending a Monthly Review with: “How much did Sales grow?”

Add one more question:
‍“Which customers and which behaviours created that growth?”

That question often gives Marketing, Sales and Management a much clearer view of what the business should do next.