ABC Analysis of Inventory: Applying 80/20 to Your Stock

A typical inventory has hundreds — sometimes thousands — of items. Spending equal management attention on each is a guaranteed way to waste time and lose the plot. ABC analysis applies the 80/20 principle to inventory: the vital few items deserve tight control, the trivial many can be managed loosely. Here is how to do it well.

The basic idea

When you sort inventory items by annual usage value (annual quantity × cost per unit), the distribution is almost always heavily skewed:

• A small number of items (~10–20%) make up a large share (~70–80%) of total value — Class A
• The next chunk (~20–30%) make up the middle (~15–25%) of value — Class B
• The bulk of items (~50–70%) make up the tail (~5–10%) of value — Class C

Class A is where the money is — and where management time should be.

How to do the classification

A practical, no-frills method:

1. List every active item with annual quantity sold × cost per unit (annual usage value)
2. Sort descending by usage value
3. Compute the running cumulative share of total value
4. Apply the cut-offs (typical: 70% / 90% / 100% of cumulative value)
5. Tag each item A, B or C

The exact percentages do not matter — what matters is that the cut-offs separate the items that demand attention from those that do not. A purist 70/20/10 split, an 80/15/5, or a 75/15/10 all work. Pick one and apply it consistently.

Why this matters

The control regime differs sharply between classes, which is where the time saving comes from:

Class A — tight control:

• Frequent reordering in small quantities to keep inventory low
• Tight forecasting with revisions monthly or even weekly
• Multiple supplier relationships for resilience
• Cycle counts every month (or even weekly for the top A items)
• Daily availability checks by the operations team
• Negotiated pricing, volume agreements, formal contracts

Class B — moderate control:

• Standard reorder point and economic order quantity
• Quarterly forecasting reviews
• Cycle counts every quarter
• Standard procurement terms

Class C — loose control:

• Bulk orders when needed (the carrying cost is trivial)
• Annual or half-yearly count is enough
• Simple min-max rules — when stock hits min, order to max
• Single supplier is fine, since the value at risk is low
• Do not waste meeting time on individual C items

The freed-up management bandwidth is the real prize. You stop micro-managing screw inventory and start watching the high-value materials that actually move the P&L.

A worked example

A workshop has 200 items in active inventory. Sorted by annual usage value:

• Top 30 items (15%) account for ₹85 lakh of ₹1.05 crore annual usage = 81% → Class A
• Next 50 items (25%) account for ₹15 lakh = 14% → Class B
• Remaining 120 items (60%) account for ₹5 lakh = 5% → Class C

The Class A items get the disciplined process. The Class C items get reordered when someone notices the bin is low. Both regimes are appropriate to the value at stake.

Combining ABC with criticality (the FSN / VED extensions)

ABC by value is the first cut. Two other dimensions are sometimes layered on:

• FSN — Fast / Slow / Non-moving — classification by movement rate, not value
• VED — Vital / Essential / Desirable — classification by criticality (a low-value item that, if missing, halts production is vital)

A combined ABC-FSN or ABC-VED matrix gives you a more nuanced control regime. A Class C item that is also "Vital" (e.g. a specific fuse or fastener critical to the line) needs tighter availability management than its value alone suggests.

For most SMEs, the basic ABC by value covers 80% of the benefit. Add FSN or VED only if the basic ABC misses obvious cases.

Revisiting the classification

Item values shift over time — a Class C item can grow into Class B as demand picks up, and vice versa. Re-classify annually for most businesses, quarterly if your product mix changes fast.

Items just below a cut-off are the volatile zone — a small change in usage can flip them. Watch the borderline cases more often than the deep-A or deep-C items.

The pitfall: managing by class only

ABC is a first lens, not the whole picture. Two warnings:

• Do not ignore C items entirely. A loose regime is not the same as no regime. C items still need a clean min-max and basic count.
• Do not stretch A controls to B and C because "more discipline is better." It is not — it is wasted time. Calibrate.

How Booksmor helps

Booksmor automatically computes ABC classification by annual usage value across your inventory, with the ability to override the cut-offs to match your industry, and recommended reorder rules per class. The classification updates as item movement changes, so you do not work off a stale list. Start a 30-day free trial and stop spending equal time on items that deserve unequal attention.