The pareto reality of any catalog.
Take any retail or wholesale SKU list of meaningful size — say 5,000 SKUs in a hardware distributor — and rank by trailing 12-month sales value. Plot cumulative sales against cumulative SKU count. You will get a curve where the top 20% of SKUs (1,000 items) account for roughly 80% of sales, the next 30% (1,500 items) account for another 15%, and the bottom 50% (2,500 items) account for 5%.
The numbers vary — sometimes it is 70/20/10, sometimes 85/12/3 — but the shape is universal. Half your catalog is producing almost no value. The opposite is also true: a small core is producing most of your business. Treating these as equally important is operational malpractice.
How abc actually classifies.
A items: top 20% of SKUs by value, producing roughly 80% of sales or COGS. These are your bread and butter. Stock them deeply, count them frequently, never run out, get the best supplier terms on them.
B items: next 30% by value, producing roughly 15% of sales. These get standard treatment — adequate stock, quarterly cycle counts, normal reorder discipline.
C items: bottom 50% by value, producing roughly 5% of sales. These get the lightest treatment — minimum stock, semi-annual counts, and a hard look every 6 months at whether they belong in the catalog at all.
- Classify by value (price × quantity sold), not just price
- Re-classify quarterly — SKUs migrate between classes
- New SKUs default to B until they have 3 months of sales history
- Some SKUs are A despite low value (insulin, regulator-mandated, key brand)
A worked example for a hardware shop.
A hardware distributor in Chicago has 4,200 active SKUs. Trailing 12 months of sales total USD 1.8 million. Running ABC: top 840 SKUs (20%) produce USD 1.44 million (80%) — these are A. Next 1,260 SKUs produce USD 270,000 (15%) — B. Bottom 2,100 produce USD 90,000 (5%) — C.
Operational implications. A items: target 30 days of cover, count monthly, supplier review quarterly, reorder triggered by min/max not just visual. B items: target 21 days of cover, count quarterly, supplier review annually. C items: target 14 days of cover or less, count semi-annually, candidates for delisting if they sit stale for two consecutive quarters. Same warehouse, three different operating disciplines.
Why c items are dangerous.
C items look harmless individually — each one moves slowly and ties up little cash. The problem is volume. A 4,200 SKU catalog with 2,100 C items means half your shelves, half your bin counts, half your receiving complexity is producing 5% of value. You are paying for warehouse space, staff time, and tax-on-stock for inventory that is barely earning its keep.
The right answer is ruthless C-class management. Set a rule: any C item with under 4 turns per year for two consecutive quarters goes on the kill list. Either order it only on customer request (no stock), find a substitute that already exists in the catalog, or delist entirely. Most businesses find they can cut catalog by 15-25% with no revenue impact, freeing meaningful working capital.
When abc gets refined into abcd or abc-xyz.
Standard ABC classifies by value alone. A second axis classifies by demand variability: X items have very stable demand (low coefficient of variation), Y items have moderate variability, Z items are erratic. Crossing the two gives 9 cells: AX through CZ. The interesting cells are AZ (high value, erratic demand — needs safety stock and forecasting attention) and CX (low value, stable demand — automate the reorder, ignore otherwise).
For most growing businesses, plain ABC is enough. ABC-XYZ becomes valuable past mid-market revenue or 10,000 SKUs, where the catalog is too complex to manage by value alone. Below that, plain ABC drives 80% of the benefit.
How nonari runs abc automatically.
Nonari computes ABC quarterly based on trailing 12-month sales value per SKU. The classification feeds three downstream systems: cycle count scheduling (A monthly, B quarterly, C semi-annual), reorder point calculations (A items get tighter safety stock), and dead stock alerts (C items with low turns flagged for review).
You can also override the auto-classification for specific SKUs — a high-margin loss leader, a regulatory-required item that must be in stock regardless of velocity, a key brand item that sets the tone of your shop. Override reasons are logged so the next manager understands why a SKU is treated as A despite low value.