Returning Customer MER (Net Sales): Retention Net Efficiency

Returning Customer MER (Net) measures what percentage of your returning customer net sales (after discounts and refunds) is spent on advertising.

Formula

RC MER (Net) = ( Total Ad Spend ÷ RC Net Order Sales ) × 100

Formula Components

Metric	Definition
Total Ad Spend	Combined advertising spend across all connected platforms
RC Net Revenue	Net order sales from returning customers after discounts/refunds

Metadata
Type	Percentage
Data Source	Shopify, Meta Ads, Google Ads
Aggregation	Ratio

Example

Your Shopify store generated $110,000 in returning customer net sales while spending $40,000 on advertising.

Metric	Value	Calculation
Total Ad Spend	$40,000	All ad platforms
RC Net Sales	$110,000	After discounts/refunds
RC MER (Net)	36.4%	($40,000 ÷ $110,000) × 100

A RC Net MER of 36.4% means you spend $0.36 on advertising for every $1 of returning customer net sales actually collected.

How It Works

RC Net MER uses returning customer net sales as the revenue base, accounting for loyalty discounts and refunds. This gives you the most accurate view of retention efficiency relative to revenue actually kept from repeat customers.

When to Use

Scenario	Action
True retention cost analysis	Include discount and refund impact
Heavy loyalty discount strategies	See real MER after promo impact
High repeat customer refund rates	Understand true marketing cost
Setting retention budget limits	Ensure RC MER allows for positive margins

Metric	Relationship
RC MER	RC MER using total revenue
RC MER (Gross)	RC MER using gross revenue
MER (Net)	Net MER for all customers
RC Net Revenue	The denominator in this calculation

See all Performance metrics →

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​Formula

​Formula Components

​Example

​How It Works

​When to Use

​Related Metrics

Formula

Formula Components

Example

How It Works

When to Use

Related Metrics