How it works
You select a collection and set a base discount percentage. Every item in the collection gets that base discount. Then the cheapest item in the customer's cart from that collection is automatically reduced to $0 — completely free.
This is more powerful than a standard BOGO because the base discount applies to everything, not just the "buy" item. The customer gets a percentage off on every item plus one free item on top. It's a stacked deal that drives significantly higher average order values.
🎁 Example: "50% Off Fall Collection, Cheapest Item Free"
Your fall collection is 50% off, and the cheapest item is free. A customer adds 3 items:
✓ Two items at 50% off + the beanie is completely free. Total savings: $168.00. The customer feels like they got an incredible deal and you moved 3 items.
Why "free" is the most powerful word in retail
Research consistently shows that "free" triggers a stronger emotional response than any percentage discount. A $28 item at 100% off feels dramatically more exciting than the same $28 savings spread across other items. Customers will add items to their cart specifically to claim the free item — increasing units per transaction.
By combining a base discount with a free item, you're creating a double incentive. The sale gets them in the door, and the free item gets them to add one more.
Real-world use cases
🛍️ Accessory Bonus
30% off dresses, cheapest item free. Customers add a scarf or clutch knowing they'll get it for free. Drives accessory sales alongside higher-ticket items.
💅 Beauty Bundle
20% off skincare, cheapest item free. Customers build a routine (cleanser, serum, moisturizer) and get the cheapest product free. Perfect for introducing new products.
🏃 Clearance Blowout
60% off clearance, cheapest item free. When you need to clear inventory fast, this is the nuclear option. Customers load up knowing they're getting the best possible deal.
🎄 Holiday Gift Promotion
25% off gifts, cheapest item free. Market it as "buy gifts for everyone on your list and get one free." Makes customers feel like they're being rewarded for their generosity.
Setting it up takes 2 minutes
Select "Buy X, Get Y Free"
Choose this promotion type from the new promotion screen.
Pick your collection
Select which collection gets the sale + free item deal.
Set the base discount
Enter the percentage off for all items (e.g., 50%). Set to 0% if you only want the free item without a base discount.
Activate
Save and go live. The cheapest item automatically becomes free at checkout.
How this differs from Shopify's Buy X Get Y
Shopify's native "Buy X Get Y" discount has several limitations. It requires a specific quantity to trigger, doesn't combine with a base percentage discount, and the setup is confusing for non-technical users. Custom Promos simplifies the entire experience: pick a collection, set a base discount, and the cheapest item is free. Done.
More importantly, Shopify's version can't stack the free item with a collection-wide percentage discount. With Custom Promos, every item gets the base discount AND the cheapest item is free — a true stacked promotion.
Frequently asked questions
Custom Promos lets you apply a base sale percentage to a collection and make the cheapest qualifying item completely free in the same promotion — something Shopify's native BOGO can't combine with a collection-wide discount.
The cheapest qualifying item in the cart is the one that becomes free, which is the standard and most customer-friendly way to run a free-item promotion.
Yes. You set the qualifying conditions during setup, so the free item only triggers when the customer meets them.
No. Custom Promos applies the discount automatically at checkout based on what's in the cart. There's no code for customers to remember, type, or get wrong — they simply see the savings as they shop.
Your discount codes work normally when no Custom Promos promotion is active. When a Custom Promos promotion is running, discount codes can't be stacked on top of it — this is intentional, to stop customers from combining a promotion with a separate coupon and discounting more than you planned.
Custom Promos runs on Shopify Functions, which are available on all standard Shopify plans. You don't need Shopify Plus.
Most promotions take under two minutes. You pick the promotion type, choose your collection with a visual picker, set your numbers, and activate. No code, no collection IDs, no developer.
Ready to offer a free item with your next sale?
Collection sale + cheapest item free. The promotion that practically sells itself.
Get Started — $24/mo →Explore other promotion types
🔥 Collection Sale + Volume Bonus
50% off + extra 10% for buying 4+
📈 Tiered Volume Discount
Buy 2 get 10%, buy 3 get 15%, buy 4+ get 20%
💰 Spend Threshold Bonus
Spend $150+ get 15% off the collection
🎯 Buy X, Get Y for Flat Price
50% off collection, cheapest item just $10
⭐ Discount on Select Item
20% off the most expensive item
🏪 Multi-Collection Sale
Shoes 50% off, clearance 75% off, buy 5+ and everything goes to 80%
🏷️ Storewide Sale with Exclusions
Everything 50% off, except Clearance