I will never forget the Great Hoodie Mix-up of 2021. I was running a small streetwear brand out of my garage, and I thought I was too cool for "corporate" things like Stock Keeping Units (SKUs). I just organized things by "piles." That worked fine until Black Friday hit. I received 50 orders in an hour. In the chaos, I grabbed what I thought was a "Black Hoodie Size Large" and shipped it to a customer in Texas. It turns out, I actually shipped a "Navy Blue Hoodie Size Medium." They looked identical under my dim garage lights. The return shipping, the angry email, and the lost customer cost me about $60, but the embarrassment was priceless.
That was the day I realized that organized data isn't boring; it is profitable. Whether you are scaling a vintage shop on Depop or managing a warehouse for Shopify, you need a system to track your stuff. If you are looking for a sku generator to save you from the "pile system," you are taking the first step toward a real business infrastructure.
What Is a SKU Number Generator? (And Why Random Numbers Fail)
If you search for a sku number maker, you will find tools that spit out random strings like 8374920. Do not use these. A random number tells you nothing. A proper SKU is "human-readable." If I see a code VINT-LEVI-501-3234, I know exactly what it is without looking at the computer: Vintage Levi's 501, size 32x34.
How to make sku numbers correctly involves creating a "logic stack."
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Brand/Category: First 3-4 letters.
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Attribute: Next 3 letters (Color/Material).
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Size/Variant: Final 2-3 characters.
Opinion Statement: I honestly believe that if your warehouse staff (or just you) cannot identify the product solely by reading the SKU on the picking list, your system is broken. Barcodes are for computers; SKUs are for people.
How to Generate SKU Numbers: The Manual Formula
Before you download a free sku generator, try building a formula in Excel or Google Sheets. It is the best way to understand your own data structure.Here’s where it gets interesting... You can use the CONCATENATE function to build thousands of SKUs in seconds.
The Formula:=CONCATENATE(LEFT(Brand,3), "-", LEFT(Color,3), "-", Size)
My Spreadsheet Anecdote: In 2023, I had to upload 200 pairs of sneakers to eBay. I used a spreadsheet to pull the first three letters of the brand (NIK for Nike), the model (Dun for Dunk), and the size (10.5). The result: NIK-DUN-10.5. It took me 10 minutes to generate sku codes for 200 items. If I had typed them manually, it would have taken all day.
Does Shopify Generate SKU? (The Platform Trap)
A common question is: does shopify generate sku numbers for you?No, generally it does not. When you create a product in Shopify, the SKU field is blank. You have to type it in. There are apps in the Shopify App Store (like "SKU Generator" or "Easy SKU") that can do it for a fee, but the native platform assumes you already have a system.
Comparison Table: Platform SKU Capabilities
Parenthetical Aside: (I once listed 50 items on Shopify without SKUs. When I tried to sync them to a 3rd party shipping tool later, the tool rejected all 50 listings because the "SKU" field was null. I had to go back and edit every single product manually. Always fill the SKU field, even if you just make it up.)
Closo Can Generate SKU: The Automated Solution
If spreadsheets scare you, automation is the answer. The Closo 100% Free Crosslister isn't just for moving listings; it manages the data behind them.Closo can generate SKU codes for you as you list.
The Workflow: When I import a listing from Poshmark to Closo, the tool can assign a unique identifier if one is missing.This is critical for cross-listing. If you sell the same item on Depop and Ebay, you need the SKUs to match so that when it sells on one, your inventory software knows which item to deduct. I use Closo to automate my inventory sync – saves me about 3 hours weekly of chasing down duplicate listings.
Sourcing Smarter: Closo Demand Signals
Generating SKUs is about managing what you have. But what about what you should buy? You can generate sku codes for 1,000 bad products, and you will just have 1,000 organized failures. I use Closo Demand Signals to ensure I am assigning SKUs to winners.
How Closo helps me predict demand across categories 6 weeks ahead is by analyzing search trends before they hit the mainstream.
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The Scenario: I was prepping my Q4 inventory in 2025.
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The Signal: Closo showed a massive spike in "Heavyweight French Terry Hoodies" (GSM 400+) while generic "Hoodies" were flat.
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The Action: I bought heavyweight blanks and assigned them premium SKUs (
HVY-HOOD-BLK). -
The Result: They sold out in November because I caught the "quality" trend early, while competitors were stuck with thin, cheap hoodies.
How to Make SKU Numbers for Bundles
How to generate a sku for a bundle (e.g., a "Outfit" of a shirt and pants) is tricky. Do not use the SKU of the shirt. Do not use the SKU of the pants. Create a new "Virtual SKU."
The Logic:
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Shirt SKU:
SHIRT-001 -
Pants SKU:
PANT-001 -
Bundle SKU:
BNDL-OUTFIT-001
Why? If you sell the bundle, your inventory system needs to know to deduct one shirt and one pant. Most basic inventory tools fail here. You need a system that supports "kitting." If you just shove the shirt SKU into the bundle listing, you will screw up your counts.
Amazon SKU Generator: The FNSKU Difference
If you sell on Amazon, you might be looking for an amazon sku generator. Amazon has its own language.
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ASIN: The product ID on Amazon's catalog.
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SKU: Your merchant ID for the product.
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FNSKU: The barcode for FBA (Fulfillment by Amazon).
Now the tricky part... Amazon will let you generate a generic SKU like X3-999-Z. But if you want to track your profit, use your own SKU logic first. When Amazon asks for the "Seller SKU," paste your NIKE-TEE-BLK-L code. This way, when you download your sales report, you know what sold. If you let Amazon generate a random string, your reports will look like algebra homework.
SKU Barcode Generator: From Screen to Label
Once you have the text (NIKE-TEE-BLK-L), you need a barcode. A sku barcode generator takes that text and turns it into scan-able lines (usually Code 128 format). You don't need expensive software. There are free fonts (like "Libre Barcode 39") you can install in Word or Google Docs.
The Process:
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Type your SKU:
*NIKE-TEE-BLK-L*(The asterisks tell the scanner where to start/stop). -
Change the font to "Barcode 39."
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Print on a DYMO LabelWriter 4XL.
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Stick it on the bag.
Honest Failure: I bought a cheap off-brand barcode scanner in 2022. It wouldn't read the barcodes I generated because I made them too small to save paper. I printed 500 labels that were unreadable.Lesson: Test your generate sku labels with a real scanner before you print the whole batch.
Organizing Without Software: The "Bin System"
If you don't have a sku generator tool yet, use the physical location as the SKU. This is called the "Bin System."
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SKU:
A1-005 -
Meaning: Shelf A, Bin 1, Item 5.
My Experience: When I started reselling on Poshmark, I used clear poly bags. I wrote "A1", "A2", "A3" on the bags with a Sharpie. In the listing description (on the hidden "Private Notes" section), I typed SKU: A1. When the item sold, I didn't care that it was a "Ralph Lauren Shirt." I just looked for bag "A1." It is the simplest free sku generator in the world.
Common Questions I See
People always ask me... Should I reuse SKUs?
Never. If you sell a "Red Dress" with SKU DRS-RED-01 and it sells out, do not use DRS-RED-01 for a "Blue Dress" next year. It messes up your historical data. If you analyze your sales in 2026, you won't know if DRS-RED-01 was the red dress or the blue dress. SKUs are permanent records.
Common question I see... How long should a SKU be?
Keep it between 8 and 12 characters. Anything shorter than 6 risks duplicates. Anything longer than 16 gets cut off on shipping labels. Amazon and eBay often have character limits (usually around 30-50), but for readability on a physical label, shorter is better.
People always ask me... Can Closo generate SKUs for Poshmark?
Yes. Poshmark has a "SKU" field hidden in the "Listing Details" section. Many sellers ignore it. Closo can populate this field when you cross-list, ensuring that your inventory tracking follows the item from Poshmark to eBay seamlessly.
Conclusion
Finding the right sku generator is not about finding a magic app; it is about adopting a mindset of order. Whether you use a spreadsheet, Closo, or a sharpie on a bag, the goal is the same: eliminate the "treasure hunt" when it is time to ship.Shipping should be boring. If shipping is exciting, you are doing it wrong.
My honest assessment is that you should start with the "Brand-Color-Size" formula in Excel today. It costs nothing, and it forces you to audit your inventory. Once you have a system, tools like Closo can help you scale it.
If you are ready to automate your inventory management across multiple channels, use the Closo Seller Hub to organize your business.
For more on managing your listings once they are organized, read our Listing Management Guide
And if you want to know which products will be filling your bins next year, check out Trending Products Forecast 2026
