Backlog vs Backorder: The Difference and How to Handle Each
Quick answer: A backorder is a customer order for an item you don't have in stock right now; you accept it and ship it when new stock arrives. A backlog is the whole pile of orders you have received but not yet shipped, for any reason: missing stock, a late supplier, a holiday, or more orders than the warehouse can pack. Every backorder sits in your backlog, but most backlog is not backorders. A backorder is a stock problem, a backlog is a capacity or process problem, and each needs a different fix.
The difference in one table
| Backorder | Backlog | |
|---|---|---|
| What it is | An accepted order for an item that is out of stock | All received orders not yet shipped |
| Root cause | Not enough stock | Not enough capacity, or a process holding orders up (stock shortages included) |
| Measured in | Units of a SKU waiting for stock | Number of orders, or days of work, waiting |
| Who sees it | The customer, as "on backorder" or a later ship date | Mostly you, until delivery dates slip |
| Typical moment | A bestseller sells out before the reorder lands | The days after a big promotion, or around a holiday |
| Fix | Restock sooner, plan stock better, set honest expectations | Add capacity, remove the bottleneck, ship oldest orders first |
How they overlap: an example
An illustrative case. On the Monday after a weekend sale, a store has 300 unshipped orders:
- 40 orders include a SKU that sold out on Saturday. These are backorders. Packing faster won't help; they need stock, a restock date and a message to each customer.
- 260 orders have every item in stock but haven't been packed, because the sale tripled the usual volume. That is backlog without backorders. It needs packing capacity, not stock.
Treating the whole 300 as one problem is how stores end up air-freighting stock they didn't need, or hiring help when the real issue was a sold-out SKU.
Backorder, pre-order or out of stock?
| Backorder | Pre-order | Out of stock (no sale) | |
|---|---|---|---|
| Product status | Normally stocked, temporarily sold out | Not released or not yet produced | Sold out, and you stop selling |
| Customer can buy? | Yes, with a later ship date | Yes, for a launch date | No; maybe a "notify me" signup |
| Main risk | Restock slips and customers cancel | Launch slips | Lost sales and lost ranking |
| Best for | Proven products with a confirmed restock date | New products and limited drops | Items with no reliable restock date |
Should you accept backorders?
Accept them when:
- The restock date is confirmed in writing, including production, inspection and shipping time.
- The wait is short compared with what customers expect in your category.
- The product is hard to substitute, so buyers are willing to wait.
- You can show the expected ship date before the customer pays.
Avoid them when the restock date is a guess, when the item is seasonal and the season might end before stock arrives, or when a marketplace you sell on penalizes late shipments. If Chinese New Year falls inside the wait, assume it will be longer than the supplier says; our seasonal inventory guide explains why.
Setting up backorders in your store
- Shopify. The setting is per variant. Turn on inventory tracking, then choose "Continue selling when out of stock". Stock then goes negative as orders come in. Shopify does not add a backorder label or ship date by itself, so add that message through your theme or product description.
- WooCommerce. Turn on stock management, then in each product's Inventory tab set "Allow backorders?" to one of three options: Do not allow, Allow but notify customer, or Allow. Avoid plain "Allow": the product keeps showing as in stock with no warning. "Allow, but notify customer" shows it as available on backorder.
- Every platform. Put the expected dispatch date on the product page, in the cart and in the order confirmation email. A date the customer saw before paying prevents most cancellation requests.
The US rule on shipping delays
If you sell to US customers, the FTC's Mail, Internet, or Telephone Order Merchandise Rule applies to online orders. In short:
- Ship within the time you state. If you state no time, you need a reasonable basis to expect to ship within 30 days.
- If you can't ship on time, you must ask for the customer's consent to the delay before the promised date, with a revised ship date (or a statement that you don't know it) and a way to cancel at no cost.
- If the customer cancels, or you don't get consent where it is required, you must refund promptly: within seven working days for most payment methods, in money, not store credit.
- If the new date also slips, you need to ask again, and this time silence does not count as consent.
This is a summary, not legal advice. The FTC's business guide to the rule spells out the notice wording and the exceptions.
How to clear an order backlog
- Sort by age. Oldest orders first, and flag any that are close to the delivery date you promised.
- Separate the two kinds. Orders with all items in stock go to packing; backordered orders go to a waiting list with a restock date.
- Decide on partial shipments. Shipping the in-stock items now and the rest later keeps customers happier but costs a second parcel. Our guide to partially fulfilled orders covers when splitting makes sense.
- Message waiting customers before they ask, with a date and the option to cancel.
- Add capacity or slow demand. Extra packing shifts, or pausing ads on the products that are holding things up, until the backlog is gone.
- Write down the cause. A backlog that isn't explained comes back after the next sale.
Preventing both
- Reorder on real lead times. Count production, inspection and freight, not just the factory's quote. See how to improve inventory management.
- Raise safety stock before known gaps: Chinese New Year, China's October holiday and your own promotion calendar.
- Warn your warehouse before every promotion, with expected order numbers, so packing capacity is planned rather than improvised.
- Track fill rate. Units shipped from stock divided by units ordered; a falling fill rate is the early warning for backorders.
How PackQuay helps
Stocked orders leave our warehouse in Xinxiang, Henan, within 24 hours (48 hours at peak), with a daily capacity of 8,000 orders. For products we don't hold in stock, we buy after your customer pays, which takes 4–5 days on average, so build that into the delivery promise as a short backorder. Message us on WhatsApp and we connect your Shopify or WooCommerce store for you: orders come in automatically, and tracking numbers go back to your store once parcels ship. You can also send orders as a CSV or Excel file. Storage is free for the first 2 months, which makes it cheaper to hold the safety stock that prevents backorders. See our storage service.
FAQ
What is the difference between a backlog and a backorder?
A backorder is an order for an item that is out of stock, accepted and shipped once stock arrives. A backlog is every order received but not yet shipped, for any reason, so backorders are one part of a backlog.
What does "on backorder" mean?
The item is sold out at the moment, but you can still order it. The seller ships it when new stock arrives, usually with an expected ship date shown at checkout.
Is it legal to take backorders in the US?
Yes, as long as you follow the FTC's mail and internet order rule: ship within the time you state, or 30 days if you state none, and if you can't, ask for the customer's consent to the delay and offer a prompt refund if they cancel.
How do I allow backorders on Shopify?
Open the product variant, turn on inventory tracking and select "Continue selling when out of stock". Shopify doesn't add a backorder message on its own, so add the expected ship date to the product page yourself.
How do I reduce an order backlog quickly?
Ship the oldest complete orders first, separate backordered orders with a restock date, consider partial shipments, tell waiting customers before they ask, and add packing capacity or pause promotions until the backlog clears.