> ## 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.

# Cost per Add to Cart: Acquisition Efficiency

> Track the average cost to generate an add to cart event. Calculate Channel Spend divided by Add to Cart Events to optimize your funnel efficiency.

<Tip>
  Average ad spend required to generate one add to cart event tracked by the Upstack pixel.
</Tip>

## Formula

<Info>
  **Cost per Add to Cart** = **Channel Spend** ÷ **Add to Carts**
</Info>

### Formula Components

| Metric                                                                                  | Definition                                               |
| --------------------------------------------------------------------------------------- | -------------------------------------------------------- |
| [**Channel Spend**](/reference/metrics/advertising/blended/blended-spend/channel-spend) | Total advertising spend across all channels              |
| [**Add to Carts**](/reference/metrics/funnel/engagement/add-to-carts)                   | Count of add to cart events tracked by the Upstack pixel |

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

***

## Example

Your campaigns spent **\$12,000** and generated **2,400 add to carts** this month:

| Channel    | Spend        | Add to Carts | Cost/Add to Cart |
| ---------- | ------------ | ------------ | ---------------- |
| Meta Ads   | \$7,200      | 1,800        | \$4.00           |
| Google Ads | \$3,600      | 480          | \$7.50           |
| TikTok Ads | \$1,200      | 120          | \$10.00          |
| **Total**  | **\$12,000** | **2,400**    | **\$5.00**       |

***

## How It Works

Cost per Add to Cart measures how efficiently your advertising converts browsers into potential buyers. Lower values indicate more cost-effective top-of-funnel acquisition. The metric uses pixel-tracked add to cart events, ensuring accurate measurement regardless of platform reporting discrepancies.

***

## When to Use

| Scenario                        | Action                                                        |
| ------------------------------- | ------------------------------------------------------------- |
| Evaluating creative performance | Compare cost per add to cart across ad sets                   |
| Optimizing funnel efficiency    | Identify channels with lowest acquisition costs               |
| Budget reallocation             | Shift spend toward lower-cost channels                        |
| Diagnosing conversion drops     | Check if add to cart costs increased before purchases dropped |

***

## Related Metrics

| Metric                                                                              | Relationship                        |
| ----------------------------------------------------------------------------------- | ----------------------------------- |
| [Add to Carts](/reference/metrics/funnel/engagement/add-to-carts)                   | The denominator in this calculation |
| [Channel Spend](/reference/metrics/advertising/blended/blended-spend/channel-spend) | The numerator in this calculation   |
| [Conversions](/reference/metrics/funnel/conversions/conversions)                    | Next step after add to cart         |

[See all Engagement metrics →](/reference/metrics/funnel/engagement)