When the box meets all rules, Subi automatically applies the configured discount.
Build-a-Box supports:
One-time purchases
Subscription purchases
Percentage discounts
Fixed amount discounts
Who Should Use Build-a-Box?
For Merchants
Build-a-Box is ideal for merchants who want to offer:
Custom product bundles
Subscription boxes
Flexible promotional product kits
For Customers
Customers can:
Build their own product box
Choose items from a curated product list
Subscribe to recurring product bundles
Step 1: Create a Build-a-Box Plan in Subi
Follow these steps to create your bundle.
Go to your Subi Subscription dashboard
Click Bundles
Click Create Bundle
Select Build a box
Each Build-a-Box plan contains the following configuration sections.
Plan Details
Enter the basic information for the bundle.
Plan title – The name of the bundle
Plan description – A short explanation for merchants or internal reference
Product Pool
Select the products customers can choose from when building their box.
Important:
Customers can only add products that are included in the product pool.
Box Options
Define the number of items required in the box.
Examples:
Box of 3 items
Box of 6 items
Customers must add exactly this number of items before the box can be added to the cart.
Discount Settings
Set the discount that will apply once the box is completed.
Supported discount types:
Percentage discount
Fixed discount amount
Each box option can have its own discount configuration.
Subscription Settings
If you want the box to be a subscription product, configure:
Subscription frequency
Subscription discount rules
Purchase Type
Choose how customers can buy the box:
One-time purchase
Subscription purchase
Both options
Save the Plan
After saving the plan, Subi generates a Box ID.
This Box ID is required to display the Build-a-Box widget on your storefront.
Step 2: Add the Build-a-Box Widget to Your Shopify Theme
Creating the plan does not automatically display the bundle on your storefront.
You must manually add the widget using the Shopify Theme Editor.
How to Add the Build-a-Box Widget
Copy the Box ID from your Build-a-Box plan in Subi
Go to Shopify Admin → Online Store → Themes
Click Customize
Click Add Block
Select Apps
Add the Build-a-Box widget
In the widget settings panel, paste the Box ID
Click Save
Once saved, the Build-a-Box section will appear on your storefront.
Important: If the Widget Is Not Showing
Check the following:
The Build-a-Box widget block was added to the theme
The correct Box ID was pasted into the widget settings
The theme changes were saved or published
The most common issue is an incorrect or missing Box ID.
Customer Experience
When the widget appears on the storefront, customers can:
Open the Build-a-Box section
Select a box size
Choose products from the available product pool
Add items until the required item count is reached
Add the completed box to the cart
A discount is applied only when the box meets all validation rules.
How Build-a-Box Discounts Work
Build-a-Box discounts are calculated per box group, not across the entire cart.
Each box group is identified using:
_build_box_id
This means:
Normal cart products do not affect Build-a-Box discounts
Multiple boxes can exist in the same cart
Each box is validated independently
Different boxes can receive different discounts
When a Discount Is Applied
A discount is applied only when all validation rules are satisfied.
Validation Rules
The following conditions must be met:
All items use the same box option (
_build_box_option_id)Purchase mode is consistent (one-time or subscription)
Total quantity equals the selected box size
All products belong to the allowed product pool
If any condition fails, the discount will not apply.
Discount Types
One-Time Purchase (Percentage Discount)
A percentage discount is applied to all items inside the box.
One-Time Purchase (Fixed Discount)
A fixed discount is distributed across the items in the box, rather than applied as a single discount line.
Subscription Boxes
For subscription purchases, discounts are applied in this order:
Build-a-Box discount
Subscription discount
Subi applies discounts sequentially, meaning each discount is applied to the already discounted price rather than simply adding discount percentages together.
This order may affect the final discount amount.
Troubleshooting
Build-a-Box Widget Is Not Showing
Check the following:
The Build-a-Box widget block is added to the theme
The correct Box ID is entered
The theme changes were saved or published
The most common issue is an incorrect or missing Box ID.
Discount Amount Looks Incorrect
Fixed Discounts
Fixed discounts are distributed across all items in the box, not applied as a single discount value.
Subscription Boxes
Subscription boxes apply discounts in the following order:
Build-a-Box discount
Subscription discount
This may change the final price calculation.
Need Help?
If you need assistance with Build-a-Box setup:
Live Chat
Available on the Subi website or inside the Subi admin panel in Shopify.
Email
[email protected]
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