Ask what it costs to hold inventory and the usual answer references warehousing and the interest on the money tied up. Both are real and together they typically account for less than half the actual figure. The rest is distributed across lines that nobody attributes to inventory, which is why holding decisions get made as though stock were nearly free.
The Components
Capital cost. The money in stock isn’t available for anything else. Value it at your genuine cost of capital or your best alternative return, not at your bank deposit rate. For most manufacturers this is the largest single element.
Storage. Rent or opportunity cost of the space, racking, utilities, handling equipment, and the labour of moving things that didn’t need to be there.
Obsolescence and deterioration. Historically your most under-estimated line. Look at what you actually wrote off over the last three years as a percentage of average holding — the number is usually higher than the assumption people carry in their heads.
Insurance and taxes, where applicable to stock value.
Shrinkage. Loss, damage, miscounting, theft. Small percentages on large balances.
Handling and administration. Counting, moving, systems, the planner time spent managing items that exist mainly because someone over-ordered.
The Costs That Never Get Counted
Two more belong in the calculation and rarely appear.
Concealment. High inventory hides operational problems. Unreliable suppliers, unstable processes, poor scheduling, and quality issues are all absorbed by buffer stock rather than exposed and fixed. The stock is paying to avoid solving problems, which is expensive twice over.
Reduced flexibility. Committed inventory constrains what you can do. Product changes get delayed because there’s stock to run out. Design improvements wait. The option value lost is real even though it never appears anywhere.
Arriving At a Number
Add the elements you can measure and express them as an annual percentage of average inventory value. Most manufacturers who do this arrive at a figure meaningfully higher than they had been assuming — often more than double the informal number in use.
Calculate it for your own business rather than adopting a published figure. The composition varies enormously: a business holding electronic components has a very different obsolescence profile from one holding steel bar.
Recalculate annually, or whenever your cost of capital changes materially. A carrying rate set when borrowing was cheap will understate the cost of inventory considerably once rates move, and decisions made on the old figure will keep favouring larger orders than the current economics justify.
Where the Number Changes Decisions
Order quantity economics. Larger orders reduce freight and administration per unit and increase carrying cost. With an accurate carrying rate, that trade-off resolves properly instead of defaulting to whatever minimises purchase price.
Safety stock levels. Knowing the true annual cost of an additional month of cover makes the service-level conversation concrete.
Supplier selection. A distant supplier requiring larger orders and longer transit carries an inventory cost that a unit-price comparison hides entirely.
ticktick.ai applies your calculated carrying rate to order quantity and stock level recommendations, so the trade-off is priced rather than assumed.
