Blog · Finance metrics and formulas · Supply chain
Carrying cost measures the expense of keeping inventory available. Calculate capital, storage, service, and risk costs, then reconcile the total by product and warehouse.
Carrying cost is the expense of keeping inventory over time: capital, storage, inventory services, and inventory risk. Add those costs for a defined period, then divide by average inventory value if you need a percentage. The useful comparison shows both dollars and the rate by SKU and warehouse.
Inventory carrying cost = Capital charge + Storage cost + Inventory service cost + Inventory risk cost
Carrying cost rate = Period carrying cost / Average inventory value for that period
The first result is an amount in dollars. The second expresses that amount as a share of the inventory investment. An annual rate needs annual costs and an inventory average representative of that year.
This is a management measure. It is distinct from the amount recorded as the inventory asset. For purchased merchandise, IRS Publication 538 describes inventory cost as purchase price after appropriate discounts plus transportation and other acquisition charges, subject to applicable capitalization rules. Do not add every management carrying cost estimate to the ledger inventory balance.
The tradeoff between placing orders and keeping stock belongs in ordering cost and carrying cost. Here the question is which costs accumulate while goods remain on hand.
Capital. Apply a finance-approved annual capital rate to average inventory value. State whether this represents borrowing expense, an opportunity cost, or another internal charge. If the chosen rate already represents financing, adding the same financing expense again counts it twice.
Storage. Include the storage portion of occupancy, utilities, equipment, and warehouse labor. Allocate by a physical driver such as occupied pallet positions or pallet-days. Receiving and dispatch labor may belong to separate transaction costs, so document the boundary.
Service. Include inventory insurance and other costs directly associated with keeping the stock. Use the actual policy or charge allocation where available. A blanket share of all corporate administration rarely explains a warehouse difference.
Risk. Include recorded obsolescence, shrinkage, damage, and spoilage within scope, net of identified recoveries. Keep an expected-loss estimate separate from realized losses. Combining both for the same exposure overstates the result.
For shared expenses, activity-based costing explains how to choose and reconcile allocation drivers. Each source expense should enter one pool once, with an owner who can explain its assignment.
Bring dated inventory valuations with SKU, warehouse, quantity, unit cost, and extended value. Bring matching expense detail with account, period, location, amount, and allocation driver. Keep write-offs linked to the affected inventory wherever the records allow.
Use daily values if inventory moves materially within a month. If only monthly snapshots exist, describe the approximation. A year-end balance can miss a seasonal buildup and make the annual carrying rate misleading.
For this illustrative US distributor, the inventory averages below are calculated from equally weighted daily closing valuations. The capital rate is an explicitly assumed 10.0% annually. Storage, service, and risk amounts are assigned annual expense pools, not industry benchmarks.
All amounts cover the same illustrative year. Percentages are shown to one decimal place; dollar calculations use unrounded inputs.
| SKU / warehouse | Average inventory (USD) | Capital at 10.0% (USD) | Storage (USD) | Service (USD) | Risk (USD) | Carrying cost (USD) | Rate |
|---|---|---|---|---|---|---|---|
| Valve A / Dallas | 200,000 | 20,000 | 18,000 | 4,000 | 6,000 | 48,000 | 24.0% |
| Pump B / Dallas | 150,000 | 15,000 | 18,000 | 3,000 | 9,000 | 45,000 | 30.0% |
| Seal C / Phoenix | 50,000 | 5,000 | 9,000 | 1,000 | 4,000 | 19,000 | 38.0% |
| Total | 400,000 | 40,000 | 45,000 | 8,000 | 19,000 | 112,000 | 28.0% |
For Valve A, capital is 200,000 × 10.0% = $20,000. Its total is 20,000 + 18,000 + 4,000 + 6,000 = $48,000, and its rate is 48,000 / 200,000 = 24.0%.
With the table's columns in A:H and product rows in 2:4, enter capital in C2, total cost in G2, and the rate in H2, respectively:
=B2*10%
=SUM(C2:F2)
=G2/B2
Fill the row formulas down. Enter =SUM(G2:G4) in G5 and =G5/SUM(B2:B4) in H5. The total rate comes from summed costs divided by summed inventory, rather than an average of the displayed rates.
First, reconcile each assigned expense pool. Storage assignments sum to $45,000, service to $8,000, and risk to $19,000. Their source reports must equal those amounts, with any exclusions listed separately. The capital charge is 400,000 × 10.0% = $40,000.
Second, reconcile across the calculation: 40,000 + 45,000 + 8,000 + 19,000 = $112,000. The product totals also give 48,000 + 45,000 + 19,000 = $112,000. A difference means an allocation was duplicated, omitted, or assigned outside the period.
Third, test the weighted rate in Excel:
=SUMPRODUCT(B2:B4,H2:H4)/SUM(B2:B4)
It returns 28.0%. Microsoft documents SUMPRODUCT as summing products of corresponding arrays. Use full-precision rates in the cells even when the display is rounded. Covirage is not affiliated with Microsoft.
Seal C has the highest rate, but Valve A has the largest dollar cost. The first flags cost intensity; the second flags total exposure. Investigate the component that drives each result before choosing an action.
Suppose Pump B's average inventory falls from $150,000 to $100,000 while the assumed capital rate remains 10.0%. Its capital charge falls from $15,000 to $10,000, a $5,000 reduction. That does not establish a storage saving or predict lower damage. Those changes need separate evidence.
Read the result alongside inventory turnover, which measures movement, and working capital, which puts the inventory investment in its broader funding context. A slow product with required service stock may still justify its carrying cost.
Upload your inventory valuation and cost allocation file, or bring a Google Sheet; Covirage maps the columns, and its tools compute and check the carrying costs by SKU and location. The external AI model explains the result with every figure traced to its rows. Create a free Covirage account and bring a sample of your own data; creating the account takes about a minute.
See Covirage for supply chain teams for the related business context.
Inventory value is the recorded cost of the goods held. Carrying cost measures the expense of keeping those goods over time. A management capital charge can be part of carrying cost without becoming part of the goods' accounting value.
Include the portion of warehouse rent assigned to inventory storage under your stated scope. Explain the allocation basis and distinguish allocated rent from avoidable expense. Reducing inventory does not save rent unless the business can release space or avoid additional capacity.
A common percentage can support an initial estimate, but it hides differences in storage intensity, insurance, damage, and obsolescence. Use a common capital rate where appropriate, then allocate the other costs using evidence specific to each product and location.