# How to Lock Quantity in Shopify Cart After Booking

# 🔒 How to Lock the Quantity in the Shopify Cart After a Cowlendar Booking

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## Prevent Customers From Changing the Booked Quantity

When you enable Cowlendar’s **Lock quantity after booking** feature, customers will no longer be able to change the quantity of a booked service from the Shopify cart.

This prevents the quantity shown in the Shopify order from becoming different from the quantity selected during the booking process. It also helps prevent accidental overbooking and keeps the booking details aligned with the final order.

![Cowlendar lock quantity after booking feature](https://orka-chat.fra1.cdn.digitaloceanspaces.com/prod/help/671a5e245d077ea954b2cd4c/import/1791976329090-image.webp)

## How to Enable Cowlendar’s Cart and Checkout Validation Rule

### 1. Open Your Shopify Settings

From your Shopify admin, click **Settings** in the bottom-left corner.

![Shopify admin Settings option](https://orka-chat.fra1.cdn.digitaloceanspaces.com/prod/help/671a5e245d077ea954b2cd4c/import/1791976328381-image2_1_.webp)

### 2. Open the Checkout Section

Inside Shopify Settings, select **Checkout**.

![Shopify Checkout settings](https://orka-chat.fra1.cdn.digitaloceanspaces.com/prod/help/671a5e245d077ea954b2cd4c/import/1791976328639-image3.webp)

### 3. Find the Checkout Rules Section

Scroll to the bottom of the Checkout settings page until you see **Checkout rules**.

![Shopify Checkout rules section](https://orka-chat.fra1.cdn.digitaloceanspaces.com/prod/help/671a5e245d077ea954b2cd4c/import/1791976328883-image4.webp)

### 4. Add and Activate the Cowlendar Rule

Click **Add rule**, then choose **cart-checkout-validation** by Cowlendar.

On the rule settings page:

1. Enter a title, such as **Cowlendar**.
2. Set the rule status to **Active**.
3. Enable **Block checkout if app experiences a problem**.
4. Click **Save** at the top of the page.

![Cowlendar cart checkout validation rule enabled in Shopify](https://orka-chat.fra1.cdn.digitaloceanspaces.com/prod/help/671a5e245d077ea954b2cd4c/import/1791976328100-1785186667328-a1wtrm27y.webp)

Once the rule has been saved and activated, customers will no longer be able to change the booked quantity in a way that creates a mismatch between the Cowlendar booking and the Shopify order.
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