> ## Documentation Index
> Fetch the complete documentation index at: https://docs.upstackdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Returning Customer CM1 MER: Repeat Order Gross Margin Efficiency

> Track returning customer CM1 MER for your Shopify store. Measure gross margin generated per dollar of ad spend on repeat orders.

<Tip>
  Returning Customer CM1 MER measures how much gross margin (revenue minus COGS) you generate from repeat orders per dollar of ad spend.
</Tip>

## Formula

<Info>
  **Returning Customer CM1 MER** = **Returning Customer CM1** ÷ **Ad Spend**
</Info>

### Formula Components

| Metric                                                                                             | Definition                            |
| -------------------------------------------------------------------------------------------------- | ------------------------------------- |
| [**Returning Customer CM1**](/reference/metrics/orders/contribution-margin/returning-customer-cm1) | Gross margin from repeat buyer orders |
| [**Ad Spend**](/reference/metrics/advertising/blended/blended-spend)                               | Total advertising spend               |

| Metadata        |                                                                                             |
| --------------- | ------------------------------------------------------------------------------------------- |
| **Type**        | Ratio                                                                                       |
| **Data Source** | [Shopify](/sources/catalog/shopify), [Advertising Platforms](/sources/catalog/facebook-ads) |
| **Aggregation** | Ratio                                                                                       |

***

## Example

Your Shopify store generates **\$60,000** CM1 from returning customers and spends **\$15,000** on ads.

| Component                      | Value    | Calculation               |
| ------------------------------ | -------- | ------------------------- |
| Returning Customer CM1         | \$60,000 | Repeat order gross margin |
| Ad Spend                       | \$15,000 | Marketing cost            |
| **Returning Customer CM1 MER** | **4.0**  | \$60,000 ÷ \$15,000       |

***

## How It Works

Returning Customer CM1 MER shows gross margin efficiency for repeat customers. This is typically higher than New Customer CM1 MER because repeat customers don't require acquisition costs—they're already in your customer base.

***

## Benchmarks

| Rating     | Range     |
| ---------- | --------- |
| Excellent  | > 4.0     |
| Good       | 2.5 – 4.0 |
| Moderate   | 1.5 – 2.5 |
| Concerning | \< 1.5    |

Returning customer CM1 MER should be meaningfully higher than new customer CM1 MER.

***

## Related Metrics

| Metric                                                                                         | Relationship             |
| ---------------------------------------------------------------------------------------------- | ------------------------ |
| [Returning Customer CM1](/reference/metrics/orders/contribution-margin/returning-customer-cm1) | Numerator (gross margin) |
| [CM1 MER](/reference/metrics/orders/performance/cm1-mer)                                       | Overall CM1 efficiency   |
| [New Customer CM1 MER](/reference/metrics/orders/performance/new-customer-cm1-mer)             | First-order efficiency   |

[See all Performance metrics →](/reference/metrics/orders/performance)