SKU Numbering System: Design the Code, Then Audit It

Use three segments: three capital letters for the category, a four-digit family number taken from a running sequence, and a short variant code. FAN-0012-WH is a white variant of the twelfth fan family. It is 11 characters, readable at a glance, and nothing in it can go stale when a supplier or price changes.

A family is all the variants of one model. The family number carries no meaning, so a supplier change or a revised material never makes the code wrong. A fully descriptive code such as FAN-CEIL-48-WHT-ORIENT breaks the first time any of those details changes.

On length, Amazon's guide to SKUs for sellers in India puts the typical SKU at 8 to 12 characters. We recommend that as your target, and 16 as the ceiling for any code. Longer codes are harder to read aloud, key in and fit on a label.

Plan the sequence for headroom. Take 5 categories × 40 models × 6 sizes × 8 colours. That is 9,600 variants, our illustration and not a measured catalogue. A single flat four-digit sequence tops out at 9,999, so that catalogue would use 96% of it on day one. Splitting the code into category, family and variant keeps every segment small.

Write the allowed values for each segment down once, in one place. An inventory data dictionary is the right home for that list.

Only details that never change belong in the SKU: category, family and the variant attributes. Everything that can change or that identifies something other than the product belongs in its own field. Warehouse is the easiest detail to get wrong: a SKU names a product, and your stock system records where it sits.

If you add a warehouse suffix such as -BLR (Bengaluru) or -HYD (Hyderabad), one product becomes two. Stock totals split, reorder levels double up and reports need merging. Keep one code per variant and read the stock per warehouse from the system.

SKU lists break through small, avoidable inconsistencies, not through bad design. These are the faults we check for:

• Letter and digit confusion. FAN-BLU-001 and FAN-BLU-OO1 look identical on a label and are two different products in your system.
• Case. Shopify's developer documentation defines a variant's SKU as a case-sensitive identifier (as of November 2026), so abc123 and ABC123 are different codes. Use capitals only.
• Lost leading zeros. A spreadsheet can treat 012345 as a number and show 12345. Start every code with a letter.
• Spaces and symbols. A slash, space or full stop can break an import or a label print. Use capitals, digits and the hyphen only, and test-print one label before you commit.
• Two spellings of one thing. One team writes MD and another MED for medium, and the same item gets two codes. A fixed list of variant values prevents this.
• HSN codes inside the SKU. Keep HSN codes in a tax field, not in the SKU, because the HSN depends on the product's tax classification and can be revised.
• Reused codes. A retired code given to a new product mixes two products' sales and stock history. Never reuse one.

Export your list and run seven pass-or-fail tests. Tests 1 to 4 are in the script below; test 5 is a sort by description in a spreadsheet; tests 6 and 7 need a scanner and a spreadsheet.

Tests 1 to 4 are in this script:

import re, collections

def norm(s):
    s = s.upper().replace("O", "0").replace("I", "1").replace("L", "1")
    return re.sub(r"[^A-Z0-9]", "", s)

def audit(skus, lo=4, hi=16):
    issues, seen = [], collections.defaultdict(set)
    for s, n in collections.Counter(skus).items():
        if n > 1: issues.append((s, "exact duplicate"))
    for s in skus: seen[norm(s)].add(s)
    for group in seen.values():
        if len(group) > 1: issues.append((sorted(group), "look-alikes"))
    for s in set(skus):
        if not re.fullmatch(r"[A-Z][A-Z0-9-]*", s):
            issues.append((s, "start with a letter; capitals, digits, hyphen only"))
        if not lo <= len(s) <= hi:
            issues.append((s, f"length {len(s)} outside {lo}-{hi}"))
    return issues

We ran it in November 2026 on a 10-entry test list we built: 9 distinct codes, with one entered twice.

Six of the nine distinct codes were flagged, and each flag was a genuine fault. The three misses are why test 5 exists: two codes with the same description are a fault only a description comparison can find. Test 6 checks that labels print and scan exactly as listed.

Add the new code beside the old one, never over it. Keep the old code as a cross-reference field, freeze it, and move stock and open orders in one planned cut-over. Overwriting old codes breaks every historic report and every supplier or customer document that quotes them. This is our recommendation, not a rule.

1. Export every item with its current code, description, unit and current stock.
2. Group by description to find items that already have two or more codes. Choose one family number for each and list the others as old codes.
3. Assign category, family and variant codes from your fixed lists.
4. Run the seven tests above on the new codes.
5. Load the new codes with the old code in a reference field. Count a sample of 20 to 30 items by new code against the shelf. Cycle counting gives a method for the schedule.
6. Retire the old codes. Do not reuse them.

We run your SKUs on Salesforce. You log in with Salesforce, set up your locations and products, and see stock for each product across all your warehouses and locations. We built Arka Inventory natively on Salesforce, so sales reps see the same figures where they create quotes and orders. Our inventory visibility feature covers on-hand stock, stock on order and lead times.

Because a SKU names one variant, we can show the stock for each warehouse without a warehouse suffix in the code.

What you get on each plan, with prices as of November 2026 from our pricing page:

• Basic: $199 a month, billed yearly, with one user licence (extra users $42 a month). Multiple warehouses, purchase orders and transfers, barcoding and packing slips, and inventory alerts.
• Advance: $499 a month, billed yearly, with two user licences (extra users $52 a month). Everything in Basic, plus bills of material, production and kitting, so a kit can be sold as a single item.
• Enterprise: custom-priced. Everything in Advance, plus sales orders, lot and serial tracking, and landed cost and bin tracking. Lot and serial tracking is where lot numbers, expiry dates and serial numbers live, so they stay out of your SKU.

As of November 2026, new accounts get a 15-day free trial with full access to all features and no credit card. As of November 2026, onboarding takes a minimum of two weeks. In our view an audited SKU list is the quickest way to keep it near that minimum. To see your own codes working across warehouses, book a demo with our team.