How do you calculate slow-moving inventory exposure?

Multiply the number of slow-moving SKUs by the average inventory value per SKU, multiply that by the write-down probability percentage, then add the fixed disposal and handling charge. With 180 SKUs at $640 each, a 45% write-down probability, and a $2,500 disposal charge, exposure is 180 x 640 x 0.45 + 2,500 = $54,340.

What counts as slow-moving inventory?

Typically any SKU whose on-hand quantity exceeds a threshold of demand — for example more than 12 months of supply, or items with no shipment in 6-9 months. The exact cutoff is a policy decision; what matters is applying it consistently so your exposure trend is comparable period to period.

What is the difference between slow-moving and obsolete inventory?

Slow-moving inventory still has demand but turns far below target, so only a fraction is at risk (the write-down probability). Obsolete inventory has no forward demand and is effectively a 100% write-down. This calculator handles the slow-moving middle ground where probability, not certainty, drives the reserve.

What is a good write-down probability to use?

There is no universal figure; it should come from your own scrap history. Many discrete manufacturers land between 30% and 60% for genuinely slow movers. The 45% used here means you expect to recover roughly half the on-hand value through eventual sales, rework, or discounting.

How does the disposal charge affect total exposure?

The disposal and handling charge is a fixed adder that applies regardless of how much inventory is written down — it covers scrap hauling, hazardous handling, or restocking fees. In the example it adds $2,500 on top of the $51,840 variable exposure, giving $54,340 total, or about $301.89 per SKU.

How often should I recalculate exposure?

Monthly at minimum, aligned to your close cycle, and again whenever a product is discontinued or a large customer program ends. Slow-moving exposure grows silently, so a monthly cadence catches accumulation before it becomes a material year-end surprise.

S&OP, Demand Planning & Forecasting calculator

Slow Moving Inventory Exposure Calculator

Slow-moving inventory exposure quantifies the dollars at risk when parts, components, or finished goods stop turning and drift toward obsolescence. Materials managers, S&OP leads, and plant controllers use it to size the potential write-down before it hits the P&L, so excess-and-obsolete (E&O) reserves are funded intentionally rather than discovered at year-end audit. It matters because slow movers tie up working capital, consume rack space, and eventually get scrapped at pennies on the dollar — and a single aging product line can quietly accumulate six figures of exposure. Running this number monthly turns a vague inventory-health worry into a defensible reserve figure and a disposition priority list.

What this calculator does

Estimates the dollar value tied up in slow-moving stock that is likely to be written down or disposed of.
An inventory planner uses it to size the obsolescence reserve before an S&OP markdown decision.
It computes the total dollar exposure of your slow-moving inventory by applying a write-down probability to on-hand value and adding fixed disposal and handling costs.

Formula used

Total exposure = slow-moving SKUs x value per SKU x write-down probability % + disposal charge
Exposure per SKU = total exposure / slow-moving SKUs

Inputs explained

Slow-Moving SKUs On Hand:
Average Inventory Value per SKU:
Write-Down Probability:
Disposal & Handling Charge:

How to use the result

Use it during monthly E&O reserve reviews, ahead of physical inventory, or when a product line is being phased out and you need to size the liquidation liability.
A single blended write-down probability across all slow-moving SKUs hides item-level variation — a discontinued custom casting may be 100% write-down while a slow but current fastener is near 0%, so segment high-value SKUs before trusting the total.

Current U.S. benchmarks

The producer price index for steel mill products stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 3,569 primary metal manufacturing establishments employing about 354,911 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate slow-moving inventory exposure? Multiply the number of slow-moving SKUs by the average inventory value per SKU, multiply that by the write-down probability percentage, then add the fixed disposal and handling charge. With 180 SKUs at $640 each, a 45% write-down probability, and a $2,500 disposal charge, exposure is 180 x 640 x 0.45 + 2,500 = $54,340.
What counts as slow-moving inventory? Typically any SKU whose on-hand quantity exceeds a threshold of demand — for example more than 12 months of supply, or items with no shipment in 6-9 months. The exact cutoff is a policy decision; what matters is applying it consistently so your exposure trend is comparable period to period.
What is the difference between slow-moving and obsolete inventory? Slow-moving inventory still has demand but turns far below target, so only a fraction is at risk (the write-down probability). Obsolete inventory has no forward demand and is effectively a 100% write-down. This calculator handles the slow-moving middle ground where probability, not certainty, drives the reserve.
What is a good write-down probability to use? There is no universal figure; it should come from your own scrap history. Many discrete manufacturers land between 30% and 60% for genuinely slow movers. The 45% used here means you expect to recover roughly half the on-hand value through eventual sales, rework, or discounting.
How does the disposal charge affect total exposure? The disposal and handling charge is a fixed adder that applies regardless of how much inventory is written down — it covers scrap hauling, hazardous handling, or restocking fees. In the example it adds $2,500 on top of the $51,840 variable exposure, giving $54,340 total, or about $301.89 per SKU.

Last reviewed 2026-05-12.