> ## 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.

# Subscription Initial Purchase Cost: Ad Spend per New Subscriber

> Calculate advertising cost per first-time subscription order. Measure subscriber CAC.

<Tip>
  Subscription Initial Purchase Cost measures your advertising spend per new subscription acquisition.
</Tip>

## Formula

<Info>
  **Subscription Initial Purchase Cost** = **Ad Spend** ÷ **Subscription Initial Purchases**
</Info>

### Formula Components

| Metric                                                                                                     | Definition                                         |
| ---------------------------------------------------------------------------------------------------------- | -------------------------------------------------- |
| [**Ad Spend**](/reference/metrics/advertising/blended/blended-spend)                                       | Total advertising cost from connected ad platforms |
| [**Subscription Initial Purchases**](/reference/metrics/funnel/conversions/subscription-initial-purchases) | Count of first-time subscription orders            |

| Metadata        |                         |
| --------------- | ----------------------- |
| **Type**        | Currency                |
| **Data Source** | [Upstack Pixel](/pixel) |
| **Aggregation** | Ratio                   |

***

## Example

You spent **\$12,000** on advertising in January and acquired **169 new subscribers**.

| Metric                             | Value    | Notes                    |
| ---------------------------------- | -------- | ------------------------ |
| Ad Spend                           | \$12,000 | Monthly advertising cost |
| Subscription Initial Purchases     | 169      | New subscribers          |
| Subscription Initial Purchase Cost | \$71.01  | Subscriber CAC           |

***

## How It Works

This metric divides your total ad spend by the number of first-time subscription orders. It represents your true subscriber acquisition cost, excluding recurring orders that aren't new customers.

***

## When to Use

| Scenario             | Action                                                |
| -------------------- | ----------------------------------------------------- |
| Subscriber CAC       | Track true new subscriber acquisition cost            |
| LTV/CAC analysis     | Compare acquisition cost to subscriber lifetime value |
| Channel optimization | Identify efficient subscriber acquisition sources     |
| Budget planning      | Forecast spend for subscriber growth targets          |

***

## Related Metrics

| Metric                                                                                                           | Relationship                        |
| ---------------------------------------------------------------------------------------------------------------- | ----------------------------------- |
| [Subscription Initial Purchases](/reference/metrics/funnel/conversions/subscription-initial-purchases)           | The denominator in this calculation |
| [Subscription Initial Purchase Value](/reference/metrics/funnel/conversions/subscription-initial-purchase-value) | Revenue from new subscribers        |
| [Purchase Cost](/reference/metrics/funnel/conversions/cost-per-purchase)                                         | Overall purchase cost               |

[See all Conversions metrics →](/reference/metrics/funnel/conversions)