Returning Customer CM3 MER: Repeat Order Contribution Margin Efficiency

Returning Customer CM3 MER measures how much contribution margin (after all variable costs including ad spend) you generate from repeat orders per dollar of ad spend.

Formula

Returning Customer CM3 MER = Returning Customer CM3 ÷ Ad Spend

Formula Components

Metric	Definition
Returning Customer CM3	Contribution margin from repeat buyer orders
Ad Spend	Total advertising spend

Metadata
Type	Ratio
Data Source	Shopify, Advertising Platforms
Aggregation	Ratio

Example

Your Shopify store generates $33,000 CM3 from returning customers and spends $15,000 on ads.

Component	Value	Calculation
Returning Customer CM3	$33,000	Repeat order contribution margin
Ad Spend	$15,000	Marketing cost
Returning Customer CM3 MER	2.2	$33,000 ÷ $15,000

How It Works

Returning Customer CM3 MER shows contribution margin efficiency for repeat orders. This is typically much higher than new customer CM3 MER because repeat orders don’t carry acquisition costs—just their share of ongoing ad spend.

Benchmarks

Rating	Range
Excellent	> 2.5
Good	1.5 – 2.5
Moderate	0.8 – 1.5
Concerning	< 0.8

Strong returning customer CM3 MER indicates healthy repeat purchase contribution.

Metric	Relationship
Returning Customer CM3	Numerator (contribution margin)
CM3 MER	Overall CM3 efficiency
New Customer CM3 MER	First-order efficiency

See all Performance metrics →

​Formula

​Formula Components

​Example

​How It Works

​Benchmarks

​Related Metrics

Formula

Formula Components

Example

How It Works

Benchmarks

Related Metrics