Quantity Limit — Complete Guide
Learn how to install, configure, and use Quantity Limit. This guide covers min/max purchase limits, Shopify Functions checkout enforcement, customer tags, lifetime caps, scheduled rules, and subscription product support.
Overview
Quantity Limit lets you set minimum and maximum purchase quantities per product, enforced at checkout using Shopify Functions. Limits are validated server-side, so customers cannot bypass restrictions by editing cart quantities or using scripts.
Key capabilities:
- Min/max quantity limits per product or variant
- Server-side enforcement via Shopify Functions
- Customer tag-based rules (wholesale vs retail)
- Per-customer lifetime purchase caps
- Scheduled rules with auto-activation
- Subscription product support
Unlike JavaScript-only solutions, Quantity Limit uses Shopify Functions to validate limits at checkout. This means limits are enforced server-side and cannot be bypassed by customers editing cart quantities or using browser scripts.
Installation
Install from Shopify App Store
Search for "Quantity Limit" in the Shopify App Store, or use the direct install link from the PantherCodX website. Click Add app to begin.
Authorize Permissions
The app requests the following permissions:
- Read products — to identify products and variants for limit rules
- Read customers — to support tag-based and lifetime cap rules
- Read/write checkout — to enforce limits via Shopify Functions
Click Install app to grant access.
Activate Shopify Function
After installation, the app automatically registers its Shopify Function for checkout validation. Go to Settings > Checkout in your Shopify admin to verify the function is active under "Additional scripts and functions."
Creating Limit Rules
Basic Min/Max Limits
Set simple quantity limits on any product or variant:
- Go to Create Rule > Basic Limit
- Select the target product(s) or variant(s)
- Set the minimum quantity (e.g., must buy at least 2)
- Set the maximum quantity (e.g., cannot buy more than 10)
- Add a custom error message for when limits are exceeded
Customer Tag-Based Rules
Set different limits for different customer segments:
- Go to Create Rule > Tag-Based
- Specify the customer tag (e.g., "wholesale", "vip")
- Set different min/max limits for tagged customers
- Example: minimum 10 units for wholesale customers, max 5 for retail
Per-Customer Lifetime Caps
Limit the total quantity a single customer can purchase across all orders:
- Go to Create Rule > Lifetime Cap
- Select the target product(s)
- Set the maximum lifetime quantity per customer
- The app tracks purchase history and blocks checkout when the cap is reached
Ideal for limited editions, promotional items, or preventing reseller abuse.
Scheduled Rules
Set time-based rules that automatically activate and deactivate (Pro plan):
- Go to Create Rule > Scheduled
- Set a start date and end date for the rule
- The rule automatically activates at the start time and deactivates at the end time
- Useful for flash sales, seasonal limits, or promotional periods
Plans & Limits
Free Plan:
- Up to 3 products/variants with full checkout enforcement
- Basic min/max limits
- Perfect for stores that only need to limit a few key items
Pro Plan:
- Unlimited products and variants
- Customer tag-based rules
- Per-customer lifetime caps
- Scheduled rules with auto-activation
- Priority support
Subscription Products
You can set quantity limits on any product type, including subscription boxes. Combined with per-customer lifetime caps, you have full control over purchase quantities for recurring orders.
The app recognizes subscription selling plans and applies limits accordingly.
Troubleshooting
Limits not enforcing at checkout?
- Verify the Shopify Function is active in Settings > Checkout
- Check that the rule is set to "Active" in the app dashboard
- Ensure the product/variant is correctly assigned to the rule
- Test with a fresh cart in an incognito window
Customer seeing wrong limit?
- Check if the customer has tags that match a tag-based rule
- Tag-based rules take priority over general rules
- Review the rule priority order in the app dashboard
Lifetime cap not counting correctly?
- Lifetime caps track purchase history from the date the rule was created
- Cancelled and refunded orders are still counted (by default) — check Settings to change this
- Guest checkouts are tracked by email address
Scheduled rule not activating?
- Ensure the start/end dates use your store's timezone
- Check that the rule is not paused in the dashboard
- Scheduled rules require the Pro plan
