Calculate total inventory carrying costs including storage, insurance, obsolescence, and opportunity cost as percentage of inventory value.
Carrying inventory costs more than what you paid for it: warehouse space, insurance premiums, capital tied up in stock, and goods that lose value before they sell. This tool adds four cost buckets - storage, insurance, obsolescence or shrinkage, and opportunity cost on the capital invested - then divides the total by average inventory value to produce a single annual carrying cost rate. The relative weight of each bucket in the total depends entirely on the inputs you supply - the calculator does not assume any fixed split between storage, insurance, obsolescence, and opportunity cost, so two businesses with the same overall rate can arrive at it through very different cost structures.
A concrete input and expected output from the current implementation.
Input
Average inventory value: $200,000. Storage/warehousing cost: $12,000/year. Insurance: $2,000/year. Obsolescence/shrinkage rate: 4% of inventory value. Opportunity cost rate: 10% of inventory value.
Expected output
Obsolescence cost = 4% x $200,000 = $8,000. Opportunity cost = 10% x $200,000 = $20,000. Total annual carrying cost = $12,000 + $2,000 + $8,000 + $20,000 = $42,000. Carrying cost rate = $42,000 / $200,000 = 21% of inventory value.
The two percentage-based components are converted to dollars against the $200,000 average inventory value before being added to the two direct dollar entries, then the sum is re-expressed as a percentage of that same base.
You enter average inventory value once, then four cost components: storage/warehousing and insurance as direct dollar amounts, and obsolescence/shrinkage and opportunity cost as percentages of inventory value. The percentage-based components are converted to dollars by multiplying each rate against the average inventory value you entered, so a higher inventory balance raises those two components even if the rate stays fixed.
The four dollar figures are summed into one annual carrying cost total. That total is then divided by the average inventory value and multiplied by 100 to produce the carrying cost rate, the figure most finance and operations teams use to compare against a target percentage or feed into reorder-quantity formulas that require a carrying cost rate as an input.
Average. Carrying cost is meant to reflect what you typically have tied up over the year, not a one-time peak. If inventory is seasonal, calculate the average from several months of balances rather than just opening and closing figures, since a two-point average can miss a mid-year spike.
Not as separate lines. The calculator itemizes only storage, insurance, obsolescence/shrinkage, and opportunity cost - if your locality taxes inventory as property, or you want to count picking and handling labor, fold those dollars into the storage figure yourself before entering it, or the result will understate your real carrying cost.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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