SKU Naming & Barcode System Starter Kit

What an SKU actually is (and the four things it isn't)

A stock keeping unit (SKU) is an internal code you assign to one specific sellable variant of a product — the 8oz lavender soy candle, the 12oz lavender soy candle, and the 8oz lavender candle in a black tin are three SKUs, not one. The four identifiers makers most often confuse an SKU with are: a UPC/EAN/GTIN barcode (an external scannable code registered with GS1 or generated locally as Code-128); a recipe ID (the formulation, which may be reused across multiple sellable variants); a batch or lot number (one specific production run, used for traceability and recall readiness); and a marketplace listing ID (Etsy listing ID, Shopify product ID, Square ID — all assigned by the platform and changed every time you recreate a listing). Confusing any of these with an SKU is the root cause of most SKU pain in growing maker businesses.

A good SKU does three jobs. It identifies one specific variant, not a product line or a category. It stays stable across reorders — last year's 8oz lavender candle and this year's 8oz lavender candle share an SKU even if you switched wax suppliers, because the customer-facing variant didn't change. And it encodes just enough information that a human reading the code can decode the variant without looking it up — CDL-LAV-8OZ-BLK is recognizable as "Candle, Lavender line, 8oz size, Black tin" by anyone trained on the prefix scheme, while 74A92B is not.

A prefix scheme that survives variants and reorders

The pattern most operating makers eventually land on is CAT-LINE-SIZE-VARIANT — four hyphen-separated blocks, 2–4 letters each, totaling 8–14 characters. CAT is the 2–3 letter category (CDL candles, SP soap, BAK baked goods, JWL jewelry). LINE is the 3–4 letter customer-facing product-line code (LAV lavender, OAT oatmeal-honey, VANI vanilla bean). SIZE is the customer-facing size as it appears on the label (4OZ, 8OZ, S/M/L, 6PK). VARIANT is one axis only — color, scent strength, packaging, or numbered edition — and the block drops entirely when the axis doesn't apply.

Use upper-case letters and digits only, and avoid putting O next to 0, I next to 1, or S next to 5 — these characters look identical in many label-printer fonts and cause scan errors and human-entry errors at the booth POS. Never embed cost, supplier, date, or any data that changes — the SKU should outlast every supplier negotiation and every cost recalculation. Never reuse a retired SKU; a year from now neither you nor a fulfillment helper will remember which variant got the recycled code.

When barcodes start paying for themselves

Barcodes are an operational tool, not a marketing requirement. The five signals that they'll save more time than they cost: picking an order takes longer than packing it (scanning is materially faster than visually matching SKUs on a shelf, and catches the wrong-variant pick before the box leaves); you ship more than 50 orders a month from your own inventory (mis-picks start costing more in reships than the scanner cost); you sell at booths or pop-ups with a tablet POS (Square, Shopify POS, and Lightspeed all scan natively); a retailer has asked for barcoded products (any major bricks-and-mortar will eventually); or your stocktake takes a full day and the numbers still drift (scanning into a system with a running balance is the cheapest way to close manual-count error toward zero).

Two or more signals describing your business is the typical "barcodes now save more than they cost" threshold. Below that, a label printer and scanner is overkill for the volume you're running.

Do you need a UPC for Etsy, Shopify, or Amazon?

Etsy does not require a UPC, GTIN, or any external barcode — the SKU field on a listing is yours to fill with your own internal code or leave blank. Shopify has an optional Barcode (ISBN, UPC, GTIN, etc.) field that's voluntary at the platform level; it's only required when you push products to Google Shopping or Meta Shop, and Google has accepted GTIN exemptions for handmade-and-customized products since 2016. Square POS scans whatever you put in front of it and matches against whatever SKU you assigned — including a barcode you printed yourself.

Where you DO need a real registered GTIN: Amazon requires it in most categories, but offers the GTIN Exemption Program (free, applied for through Seller Central) for handmade and private-label brands. Walmart Marketplace and Target both require GS1-registered codes. Faire and indie wholesalers vary — ask before you buy. The pragmatic staged path for most makers: Stage 1, print free Code-128 barcodes of your internal SKUs for in-house ops; Stage 2, apply for the free Amazon GTIN Exemption if and when you add Amazon; Stage 3, only buy registered GS1 codes ($30 setup + ~$30/yr renewal for a single code, ~$250/yr for a 10-code prefix) if you land a national retail account.

What is an SKU and how is it different from a barcode?

An SKU (stock keeping unit) is an internal code you assign to one specific sellable variant of a product — the 8oz lavender candle in a black tin gets one SKU; the 12oz version gets a different SKU. A barcode (UPC, EAN, or GTIN) is an external scannable code: either a globally unique identifier registered through GS1 for retail compliance, or a locally generated Code-128 barcode of your internal SKU for in-house operations. You own and control your SKUs; UPCs are registered against your business through GS1. Most growing makers can use their internal SKUs printed as Code-128 barcodes for in-house ops and only need GS1-registered UPCs if they sell on Amazon, Walmart, or in national bricks-and-mortar retail.

How do I create SKUs for handmade products?

Use a short repeatable prefix pattern: CAT-LINE-SIZE-VARIANT. CAT is a 2–3 letter category code (CDL candles, SP soap, BAK baked goods, JWL jewelry). LINE is a 3–4 letter customer-facing product-line code (LAV lavender, OAT oatmeal-honey, VANI vanilla bean). SIZE is the customer-facing size as it appears on the label (4OZ, 8OZ, S/M/L, 6PK). VARIANT is one axis only — color, scent strength, packaging, numbered edition — and you drop the block entirely when the axis doesn't apply. Use upper-case letters and digits only, 8–14 characters total, avoid characters that look alike (O/0, I/1, S/5). Three example SKUs in this format: CDL-LAV-8OZ-BLK (lavender soy candle, 8oz, black tin), SP-OAT-1BAR (oatmeal-honey soap, single bar), JWL-HOOP-GF-M (gold-fill hoop earrings, medium).

Do I need a barcode or UPC for my Etsy shop?

No. Etsy does not require a UPC, GTIN, or any external barcode for any listing — the SKU field on each listing is yours to fill with your own internal code or leave blank. Etsy will never reject a listing for missing a barcode. Most Etsy sellers run their entire shop without a barcode for years, and only revisit the question if they expand to Amazon (which offers a free GTIN Exemption for handmade and private-label brands), Walmart, Target, or national bricks-and-mortar retail.

Do I need a barcode for Shopify?

Not at the platform level. Shopify has an optional Barcode (ISBN, UPC, GTIN, etc.) field on every product, but it's voluntary and you can leave it blank. The only time Shopify's barcode field becomes required is when you push products to a downstream channel that needs one — Google Shopping and Meta Shop both ask for a GTIN by default, though Google has accepted GTIN exemptions for handmade-and-customized products since 2016. For Shopify POS at a booth or pop-up, the barcode field can hold any code (including a Code-128 of your internal SKU that you printed yourself) and the POS will scan it.

How much does a GS1 UPC cost?

GS1 US (gs1us.org, the only authorized US issuer of registered GTINs) charges a one-time $30 fee for a single GTIN, then $0–$2/year renewal. For a 10-code prefix (which gives you a registered GS1 company prefix that can encode up to 10 unique products), it's ~$250/year. For 100 codes, ~$500/year. Brokers like Speedy Barcodes and Nationwide Barcode resell unused company-prefix tiers from older businesses at $5–$15 per code — these scan fine at most retailers but are not accepted by Amazon (since 2016), Walmart, or Target, because those retailers cross-check the prefix against the registered brand. For most maker businesses, the pragmatic answer is to use free Code-128 barcodes of your internal SKUs in-house, apply for the free Amazon GTIN Exemption if you add Amazon, and only buy GS1-registered codes when a major retailer specifically requires them.

What is the Amazon GTIN Exemption Program?

A free program administered through Amazon Seller Central that lets sellers list products without a GTIN (UPC/EAN) in eligible categories — including most handmade and private-label categories. You apply per-brand-per-category, submit images of the unbranded product or branded packaging, and Amazon typically approves within 48 hours. The exemption is the right answer for handmade brands on Amazon: free, official, and avoids the need to buy GS1 codes you don't otherwise need. The exemption can be denied if Amazon decides a category should require GTINs, in which case GS1-registered codes become the only path.

Why shouldn't I buy a $5 UPC from a broker?

Resold broker UPCs ($5–$15 each from sites like Speedy Barcodes or Nationwide Barcode) are technically legitimate GS1 codes — they come from company prefixes assigned years ago and never used. The codes scan fine at most retailers and on most POS systems. The problem is that Amazon, Walmart, and Target all cross-check the GS1 prefix against the registered brand, and a code that scans as belonging to a defunct 1990s company doesn't pass that check. Amazon banned resold UPCs in 2016 specifically because the brand-to-prefix mismatch was causing listing-merge errors. If you might ever sell on Amazon, Walmart, or Target, don't buy resold codes — apply for the Amazon GTIN Exemption (free) or buy directly from GS1.

Should I reuse SKUs that I've retired?

No. Once an SKU is retired, it stays retired — a year or two from now you won't remember which variant got the recycled code, and a part-time helper, a wholesale buyer, or your future inventory software definitely won't. The cost of "saving" an SKU code is essentially zero (the SKU namespace is enormous); the cost of a customer receiving the wrong product because two variants shared a code across time is large. Treat retired SKUs as permanently retired, and pick the next sequential or descriptively-different code for the new variant.

How many characters should an SKU be?

8–14 characters is the practical sweet spot. Long enough to encode CAT-LINE-SIZE-VARIANT without abbreviating beyond recognition; short enough to fit on small product labels, in Etsy CSV exports (which truncate long SKUs in some report views), and on wholesale purchase orders without wrapping. SKUs shorter than 6 characters tend to lose readability — you can't tell what variant they encode. SKUs longer than ~16 characters start being hard to read aloud over the phone to a wholesale buyer and start truncating in some software UIs. Aim for the band, hyphens between blocks, upper-case letters and digits only.