Returning Customer MER: Repeat Order Marketing Efficiency

Returning Customer MER measures what percentage of returning customer order revenue is spent on advertising—marketing efficiency for retention.

Formula

RC MER = ( Ad Spend ÷ RC Order Revenue ) × 100

Formula Components

Metric	Definition
Ad Spend	Total advertising spend
RC Total Revenue	Revenue from returning customer orders
customer_type = returning_customer	Filters to repeat buyers

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

Example

Your store spent $20,000 on ads and returning customers generated $120,000 in revenue.

Component	Value	Calculation
Ad Spend	$20,000	Total advertising
RC Revenue	$120,000	Repeat buyer revenue
RC MER	16.7%	$20,000 ÷ $120,000 × 100

How It Works

RC MER shows marketing efficiency for returning customers. It’s typically lower than NC MER because repeat customers don’t require acquisition cost—they’re already in your database. The gap between NC MER and RC MER shows the efficiency gain from retention.

When to Use

Scenario	Action
Measuring retention efficiency	Track RC MER vs NC MER
Validating retention value	Lower RC MER = more efficient repeat business
Budget allocation	Shift spend toward segments with better MER
LTV modeling	Use RC MER for lifetime value projections

Metric	Relationship
MER	Overall marketing efficiency ratio
NC MER	MER for new customers
LTV	Customer lifetime value

See all Performance metrics →