> ## 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.

# Unique Purchases: Session-Deduplicated Conversions

> Track unique purchase events for your Shopify store. Session-deduplicated count of completed orders for accurate funnel conversion measurement.

<Tip>
  Unique Purchases counts purchase events deduplicated by session, ensuring each session is counted only once regardless of multiple purchase events.
</Tip>

## Formula

<Info>
  **Unique Purchases** = **COUNT DISTINCT** ( Sessions with Purchase )
</Info>

### Formula Components

| Metric                     | Definition                                              |
| -------------------------- | ------------------------------------------------------- |
| **Sessions with Purchase** | Sessions where at least one purchase event was recorded |

| Metadata        |                                                              |
| --------------- | ------------------------------------------------------------ |
| **Type**        | Number                                                       |
| **Data Source** | [Upstack Pixel](/pixel), [Shopify](/sources/catalog/shopify) |
| **Aggregation** | Count                                                        |

***

## Example

Your Shopify store recorded **892 unique purchases** in January, even though total purchase events reached 1,024 (some sessions had multiple purchase events).

| Week   | Unique Purchases | Total Events | Deduplication Rate |
| ------ | ---------------- | ------------ | ------------------ |
| Week 1 | 205              | 238          | 13.9% duplicates   |
| Week 2 | 228              | 261          | 12.6% duplicates   |
| Week 3 | 217              | 249          | 12.9% duplicates   |
| Week 4 | 242              | 276          | 12.3% duplicates   |

***

## How It Works

The Upstack Pixel tracks purchase events when customers complete checkout on your Shopify store. Unlike total purchase event counts, Unique Purchases deduplicates by session—if a visitor triggers multiple purchase events within the same session (due to page refreshes, payment retries, or tracking redundancy), only one purchase is counted. This provides a more accurate conversion count aligned with actual Shopify orders.

***

## When to Use

| Scenario                     | Action                                                          |
| ---------------------------- | --------------------------------------------------------------- |
| Accurate conversion counting | Use when you need true order counts without tracking duplicates |
| Funnel analysis              | Measure real session-to-purchase conversion rates               |
| Attribution accuracy         | Ensure 1:1 mapping between attributed sessions and conversions  |
| Comparing against Shopify    | Validate tracking accuracy against Shopify Admin order counts   |

***

## Related Metrics

| Metric                                                                                   | Relationship                                 |
| ---------------------------------------------------------------------------------------- | -------------------------------------------- |
| [Order Placed](/reference/metrics/funnel/conversions/order-placed)                       | Total order events (may include duplicates)  |
| [Conversion Value](/reference/metrics/funnel/conversions/conversion-value)               | Total monetary value of conversions          |
| [Session Conversion Rate](/reference/metrics/funnel/conversions/session-conversion-rate) | Percentage of sessions resulting in purchase |

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