What Is ABC Analysis?
ABC analysis ranks inventory into three tiers — A, B, and C — based on each item's contribution to value. Here is the definition, the formula, a worked example, and how it compares to XYZ analysis.
Free Starter plan · Export product data · No credit card
01 — Overview
ABC analysis, defined
ABC analysis ranks your products by how much value they contribute to your business, then groups them into three tiers. The value used is usually annual usage value — unit cost × annual quantity — not just unit price or unit volume alone.
Rank
Calculate annual usage value per SKU: unit cost × annual quantity.
Sort
Order every SKU from highest usage value to lowest.
Split
Draw A/B/C lines where the cumulative-value curve breaks.
Control
Apply tighter rules to A, lighter rules to C.
ABC analysis ranks products into three tiers (A, B, C) by their contribution to value — usually annual usage value — not by unit count or unit price alone.
It follows the Pareto principle: a common guideline is roughly 20% of SKUs ("A" items) driving 70-80% of value, while "C" items are numerous but individually low-impact.
The point is differentiated control: tight tracking and frequent counts on A items, progressively lighter-touch management on B and C items.
02 — The A/B/C tiers
Three tiers, three levels of control
The point of the classification is differentiated effort: tight tracking where it pays off, lighter rules everywhere else.
Tier A — high value, tight control
Typically the top ~20% of SKUs by usage value, contributing roughly 70-80% of total value. These get frequent cycle counts, precise reorder points, and the most supplier-negotiation attention — the payoff from tighter control is highest here.
Tier B — moderate value, standard control
The next ~30% of SKUs, contributing roughly 15-20% of value. Standard periodic review and normal reorder rules are usually enough — not worth A-item effort, but still tracked deliberately.
Tier C — low individual value, light control
The remaining ~50% of SKUs, contributing only around 5-10% of value individually. Looser control, simpler reorder rules, and bulk ordering keep effort proportional to impact.
03 — Formula
How to calculate ABC classification, step by step
The same four-step method applies whether you have 50 SKUs or 50,000.
1. Calculate
Usage value per SKU = unit cost × annual quantity used or sold.
2. Sort
Order every SKU from highest usage value to lowest.
3. Cumulate
Running total of usage value as a % of the full catalog.
4. Classify
Draw A/B/C lines wherever the cumulative curve breaks.
These percentages are a starting guideline, not a rule to hit precisely — the point is the relative concentration of value, not an exact cutoff. Use the ABC analysis tool to run this on your own catalog.
04 — Worked example
A small catalog, classified
Five SKUs sorted by usage value, high to low, with the cumulative percentage that determines each tier.
Usage value drives the split, not unit price
Steel Hinge Pack costs $2 a unit but sells 9,000 a year — its usage value earns it Tier A alongside a $34 bar stool. A unit-price-only ranking would have missed that entirely.
- Unit cost × annual quantity = usage value
- Sort descending, then track cumulative %
- Draw tier lines where the curve breaks
05 — Vs. related methods
ABC analysis vs. XYZ analysis vs. the 80/20 rule
These terms get used interchangeably. Here is what each one actually measures.
| Method | What it measures |
|---|---|
| ABC analysis | Ranks SKUs by contribution to value (usually usage value) into three control tiers. |
| XYZ analysis | Ranks SKUs by demand variability/predictability instead of value — often combined with ABC as "ABC-XYZ." |
| 80/20 (Pareto) rule | The general principle ABC analysis applies to inventory: a minority of items driving most of the value. |
| Simple unit-volume ranking | Ranks by units sold only — can misclassify a cheap, high-volume item as more important than an expensive, low-volume one. |
For the combined method, see ABC-XYZ analysis.
06 — Pitfalls
Where ABC classification goes wrong
Most issues come from one of these four mistakes, not a flaw in the method itself.
Using unit price, not usage value
Ranking by price alone hides high-volume cheap items that actually drive real value.
Never re-running it
A one-time classification goes stale as sales mix shifts — revisit it quarterly or after big demand changes.
Ignoring lead time and risk
A low-value C item with a long, unreliable lead time can still deserve tighter control than its tier suggests.
Treating C items as unimportant
C items are low-impact individually, not disposable — a stockout still loses the sale.
Export, then classify
StockFlow doesn't auto-generate an ABC report today — export product and cost data and run the calculation yourself.
Tag items by tier
Label products A, B, or C so counting frequency and reorder rules can differ by tier.
Frequently asked questions
What is ABC analysis?
ABC analysis is a method of ranking inventory into three tiers — A, B, and C — based on each item's contribution to value, usually annual usage value (unit cost × annual quantity). "A" items are typically a small number of SKUs that drive most of the value; "C" items are numerous but individually low-impact.
What is the full form of ABC analysis?
ABC is not an acronym for a phrase — the letters A, B, and C simply label the three value tiers the method sorts inventory into, in descending order of importance.
What is ABC analysis in inventory management?
In inventory management, ABC analysis classifies SKUs into three control tiers based on contribution to value so you can apply tighter tracking, more frequent counts, and more precise reorder points to your highest-impact items, and lighter-touch management to the rest.
How do you calculate ABC classification?
Calculate annual usage value per SKU (unit cost × annual quantity), sort from highest to lowest, then split into three tiers based on cumulative value contribution — a common guideline is roughly 70-80% of value in the top ~20% of SKUs (A), 15-20% in the next 30% (B), and the remainder in the bottom 50% (C).
What are the different types of ABC analysis?
The core method (ranking by usage value) is the same; variations differ in which value is ranked — annual usage value is most common, but some businesses classify by profit margin, order frequency, or criticality instead. Combining ABC with XYZ analysis (demand variability) is a common extension called ABC-XYZ analysis.
What is an ABC ranking system?
"ABC ranking system" is another name for ABC analysis: SKUs are ranked by usage value and split into three tiers so control effort matches each item's actual impact.
What is an ABC breakdown of inventory?
An ABC breakdown shows what share of your SKUs and what share of your inventory value falls into each tier — for example, "20% of SKUs (Tier A) account for 78% of usage value."
What is the difference between ABC analysis and XYZ analysis?
ABC analysis ranks items by contribution to value. XYZ analysis ranks items by demand variability — X items have stable, predictable demand; Z items are erratic. The two are often combined (ABC-XYZ) so a high-value item with erratic demand (AZ) gets different handling than a high-value item with steady demand (AX).
Does StockFlow run ABC analysis automatically?
StockFlow does not generate an automated ABC classification report today. You can export your product and stock data (including cost) to calculate usage value and classify SKUs yourself, then tag items by tier and apply different minimum-stock-level and counting practices per tier.
How often should ABC classification be updated?
Quarterly is a reasonable default for most catalogs, or sooner after a major sales mix shift, new product launch, or seasonal swing. A classification run once and never revisited tends to drift out of sync with actual usage value.
Track the cost data ABC analysis needs
StockFlow tracks per-SKU cost and usage so you can export accurate data for classification — free for up to 25 products.