A customer checks out, then places a second order minutes later. If you fulfill both as-is, you pay for two labels, two boxes, and two trips through your packing process - to send items to the same address. Here is how to combine shipping on Shopify instead.
The short answer: Shopify has no combined shipping feature for existing orders. Either fulfill both orders in one physical package (and handle tracking and any shipping refund manually), or merge the orders into one with an app like MergeIt so there is only one order to fulfill and one label to buy.
What Double Orders Actually Cost You
Every unmerged double order costs you:
- A second shipping label - typically $8-12 for domestic packages, far more internationally
- A second box and packing materials
- Handling time - picking, packing, and processing two shipments
- Customer confusion - two tracking numbers, two delivery windows, and "where is the rest of my order?" emails
If your store sees ten double orders a month at a $10 average label cost, that's $100+ a month in pure waste before counting packaging and time.
Option 1: Ship Both Orders in One Package (Manual)
You can simply pack both orders into one box, buy one label, and mark both orders as fulfilled with the same tracking number.
✅ Pros:
- No app, no order changes
- Works for a rare one-off
🚨 Cons:
- Both orders still exist - reports show two shipments that were really one
- You have to remember to add the same tracking number to both orders
- The customer paid shipping twice and expects a refund you must process manually
- Easy to miss double orders entirely unless someone checks addresses on every order
The hard part is the last one: spotting double orders. On a busy store, nobody notices that order #1042 and #1047 go to the same person.
Option 2: Merge the Orders, Then Ship Once
The cleaner fix is to combine the two orders into one before fulfillment, so there is only one order, one shipping line, and one fulfillment. Shopify can't do this natively (see how to combine orders on Shopify), but an order merging app can.
How it works with MergeIt:
- MergeIt spots new orders from the same customer for you
- A smart rule auto-merges them - for example when placed within 24 hours with the same shipping address - or sends you an email suggestion to confirm
- The merged order keeps sales and tax data intact, so your reports stay accurate
- You fulfill one order, buy one label, and the customer gets one tracking number
MergeIt shows you the shipping saved per merge, and every merge can be undone from the merge history if plans change.
Don't Forget the Customer's Shipping Fee
If the customer paid for shipping on both orders and you ship once, refund the second shipping fee. It prevents support tickets and chargebacks, and you still come out ahead: you keep one shipping fee and pay for one label instead of two.
Some merchants keep both fees when shipping was underpriced to begin with - but silently pocketing a fee for a shipment that never happens is how you lose repeat customers.
When Combining Shipping Is Worth It
| Double orders per month | Recommendation |
|---|---|
1-2 | Handle manually, watch for repeat patterns |
3-10 | Merging app pays for itself in labels alone |
10+ | Auto-merge rules, hands-off |
MergeIt starts at $14.99/month including 50 merges with a 7-day free trial - at a $10 average label, two merges a month break even. Install it from the Shopify App Store.
🎯 Key Takeaways
- ✓ Shopify has no combined shipping for existing orders - it's manual or an app
- ✓ Every unmerged double order costs you a label, a box, and handling time
- ✓ Merging orders before fulfillment gives you one order, one label, one tracking number
- ✓ Refund the second shipping fee when you ship once - you still save money
- ✓ Auto-merge rules catch double orders you'd never spot by hand