How to add SKU to product variants on Shopify
SKUs (Stock Keeping Units) – These are internal codes assigned to specific variants within your product’s inventory. An example of a SKU for the Classic Tee (shown above) would be “CTEE-RED-M” which clearly indicates to your fulfillment team that they are picking a Classic Tee, Red, Medium. Without SKUs, the fulfillment team would need to read the variant titles such as “Red / Medium” which is slower, more prone to errors and does not integrate with any inventory management systems.
Shopify automatically assigns a SKU field to every variant, but it is optional and will default to nothing. Many shop owners opt to leave this field blank, especially when they are first starting to build their store. They do not think about all of the complexities that come with managing a larger number of products. It is not until they have built a large store with 500 products that they can no longer keep track of their inventory levels, can not integrate with their 3PL, or can not match the items that need to go back to customers. It is very painful to go back through a large store and assign SKUs to all of the products. It is easier to do it from the start.
In this post
- Why SKUs matter
- Adding SKUs manually
- SKU naming conventions
- Bulk editing SKUs
- Adding SKUs via CSV
- FAQ
Why SKUs matter
- Warehouse efficiency. A picker scanning “CTEE-RED-M” finds the item faster than reading “Classic Tee Red / Medium” on a packing slip.
- 3PL and fulfillment integration. Third-party logistics providers match incoming orders to physical stock using SKUs. Without them, integration breaks.
- Inventory tracking. SKUs let you track stock levels per variant in spreadsheets, ERP systems, and accounting software. “How many CTEE-RED-M do we have?” is a quick lookup. “How many Red Medium Classic Tees?” requires parsing text.
- Returns processing. Matching a returned item to the correct variant is instant with a SKU scan. Without one, staff has to visually identify the color and size and manually find the variant.
- Google Shopping feed. SKUs populate the
idoritem_group_idfields in your product feed. Consistent SKUs improve feed quality and ad performance.
Adding SKUs manually
- Go to Products and open a product
- Scroll to the Variants section
- Click a variant to expand it
- Fill in the SKU field
- Repeat for each variant
- Save
This is fine for small shops with a handful of products. If you have a large catalog of hundreds of products with thousands of variants, use the bulk editor or the CSV import instead.
SKU naming conventions
A good SKU system should have consistency, scannability, and scalability. One common format to follow is [PRODUCT]-[OPTION1]-[OPTION2]
| Product | Color | Size | SKU |
|---|---|---|---|
| Classic Tee | Red | Small | CTEE-RED-S |
| Classic Tee | Navy Blue | XL | CTEE-NAV-XL |
| Leather Wallet | Brown | Standard | LWLT-BRN-STD |
| Ceramic Mug | White | 12oz | CMUG-WHT-12 |
Rules that prevent headaches later:
- Uppercase only. Avoids case-sensitivity issues in external systems.
- Hyphens as separators. More readable than underscores and do not cause issues in spreadsheets or databases.
- 3 to 4 letter abbreviations. “RED” not “R”, “NAV” not “NAVYBLUE”. Short enough to scan, long enough to be unambiguous.
- No spaces or special characters. Spaces break CSV imports and barcode scanners. Stick to letters, numbers, and hyphens.
- Unique across your entire catalog. No two variants anywhere in your store should share a SKU. If they do, inventory tracking, order management, and analytics all break.
Bulk editing SKUs
For existing products that need SKUs added:
- Go to Products
- Select the products you want to edit
- Click Edit products (bulk editor)
- Click Columns and add “SKU”
- Fill in SKUs in the spreadsheet view
- Save
The bulk editor will display every variation for the selected products in a table format to make editing faster and easier. You can enter the SKU’s manually, or copy and paste a long list from a spreadsheet such as Microsoft Excel or Google Docs. If you have patterns in your store with the same base product prefix and incrementing suffix (e.g. p001, p002, p003 etc) then it is recommended to first generate and prepare the long list of correct SKUs in a normal spreadsheet, then paste the column of SKU’s into the appropriate column in the Shopify bulk editor.
Adding SKUs via CSV
For large catalogs, the CSV method is fastest:
- Export your products as CSV from Products > Export
- Open in Google Sheets or Excel
- Find the “Variant SKU” column
- Fill in SKUs using formulas or manual entry
- Import the updated CSV back to Shopify
Formula to automatically generate sku from column headers: =UPPER(LEFT(A2,4)&”-“&LEFT(B2,3)&”-“&C2). For this example, A2 would be product title (e.g. Classic Tee), B2 color (e.g. Red), C2 size (e.g. M). It would return CLAS-RED-M. You would have to review and alter to suit your needs. Once correct, you can paste into bulk import.
SKUs are especially important when working with variant images. Apps like Rubik Variant Images use variant data (including SKUs) when doing AI auto-assign and bulk operations. Consistent SKU naming helps with matching images to variants because the patterns are predictable. And for stores using Rubik Combined Listings to group separate products, each product maintains its own SKU scheme, keeping inventory clean across the group.
“I have been really impressed with this app. Even though it is simple in it’s purpose, it is easy to use, and does exactly what I need. I also like how responsive the support is too. I had a small suggestion for an improvement, and the team tried to understand my use case, then actually implemented a change to it that same day! I wish some of my other app providers were as responsive as these guys.”
Daily Bloom, US, Rubik Variant Images on the Shopify App Store
Frequently asked questions
Are SKUs required on Shopify?
Optional. SKU’s are not required for Shopify to function. However they are highly recommended for any volume sellers, 3PL users or businesses that are integrating with external products and inventory systems. Without SKU’s businesses typically resort to manually entering product information which can be time-consuming and error prone.
What is the difference between SKU and barcode on Shopify?
SKUs are internal codes you create (like “CTEE-RED-M”). Barcodes are standardized codes (UPC, EAN) used for scanning at point of sale and by retailers. A variant can have both. SKUs are for your internal operations. Barcodes are for external systems and retail partners.
Can two variants have the same SKU?
Shopify allows you to duplicate SKUs but it is very bad practice. Your inventory management, your order fulfillment and even external integration will all be negatively affected if you have duplicate SKUs. Every variant within your store should have a unique SKU.
Can I change a SKU after the variant has orders?
Yes. Existing orders will continue to have the original SKU assigned to them at time of purchase. Future orders will use the new SKU for products with updated SKUs. It is recommended that integration partners update SKUs in external systems as well.
How do I generate SKUs for hundreds of variants?
Export all products out as a CSV file, then use spreadsheet formulas to produce the SKUs based on the product title and the option values. Fill in some placeholder information in the title, color, and size fields, and then use the following spreadsheet formula to create the SKUs: =UPPER(LEFT(title,4)&”-“&LEFT(color,3)&”-“\&size) > Make sure you review these SKUs for any edge cases before importing them in.
