Carrying Costs Explained: The Hidden Price of Overstocking on Shopify

Inventory carrying costs are the total annual expenses of holding unsold stock, covering capital tied up in product, storage space, insurance, shrinkage, and obsolescence risk. For most Shopify merchants, those costs run between 20% and 30% of average inventory value every year. That means a store holding $200,000 in stock is quietly spending $40,000 to $60,000 simply to keep that inventory sitting on shelves.

Key takeaways

• Carrying costs typically equal 20-30% of total inventory value per year, across capital, storage, risk, and service costs.
• Capital cost (the opportunity cost of money locked in stock) is usually the single largest component, around 15% of inventory value on its own.
• Overstocking costs global retailers an estimated $800 billion annually, a figure that compounds when slow-moving SKUs are ignored.
• The formula is simple: Carrying Cost % = Total Annual Holding Costs ÷ Average Inventory Value × 100.
• Knowing your carrying cost per SKU changes reorder decisions from gut feel into math you can defend.

What exactly is a carrying cost (and what does it include)?

A carrying cost, also called a holding cost, is every dollar you spend owning inventory before it sells. It is not just a warehouse bill. It has four distinct layers:

• Capital cost: the opportunity cost of cash locked in product. If your cost of capital is 10-12%, every dollar tied up in slow stock costs you that rate in foregone returns or interest. This is typically the largest slice, around 15% of inventory value by itself.
• Storage cost: warehouse rent, utilities, security, and maintenance. The average US warehouse charges $15-25 per pallet per month, so a 500-pallet overstock adds $7,500, $12,500 in direct monthly cost.
• Service cost: insurance, inventory software, labor for cycle counts, and taxes on goods in hand.
• Risk cost: shrinkage, damage, expiration, and the markdown exposure on fashion or electronics that depreciates the moment a new season or model arrives.

For a deeper look at how each of these feeds into your reorder math, see the inventory forecasting glossary.

How to calculate your carrying cost percentage

The standard formula:

Carrying Cost % = Total Annual Holding Costs ÷ Average Inventory Value × 100

A worked example: if you hold an average of $300,000 in inventory and your combined annual holding expenses (storage, insurance, capital cost, shrinkage) total $72,000, your carrying cost rate is 24%. Every SKU in your catalog is, on average, costing you 24 cents per year for every dollar of product value it represents.

Where most Shopify merchants go wrong is measuring only the warehouse bill. When you leave out capital cost and risk cost, you systematically underestimate the true drag on margin, sometimes by a factor of two.

The four cost categories benchmarked by industry

Carrying costs are not uniform. Electronics sellers face faster depreciation; apparel merchants face seasonal obsolescence; consumables face expiration. Here is a practical benchmark table:

If your store sits in the 20-30% band, you are in the typical range for multi-channel ecommerce. If you are above 30%, excess stock is almost certainly the cause, not your cost of space.

Why overstocking accelerates carrying costs (the compounding problem)

Overstocking is not a one-time mistake. It is a compounding one. Consider a product that is 300 units overstocked relative to actual 90-day demand. Each week it sits, you pay:

1. Capital cost on the full value of those units.
2. The same storage footprint as fast-moving SKUs, which means your best sellers compete for the same shelf space.
3. Increasing markdown risk: a product that has been in warehouse for six months is far harder to sell at full price than one that arrived last month.
4. Opportunity cost on the cash that could have funded a reorder of a genuine best-seller running low.

With a standard 25% annual carrying rate, $100,000 in dead or slow-moving overstock costs $25,000 in year one, $50,000 cumulative by year two. The stock does not need to become worthless to be expensive. It just needs to sit.

IHL Group research cited in Shopify's own inventory data estimates that overstocks alone account for roughly $800 billion of the global $1.77 trillion inventory distortion figure. For a mid-market Shopify merchant doing $500,000 in annual revenue, even a modest 3% overstock drag equals $15,000 in eroded margin per year.

Before vs. after: reorder decisions with and without carrying cost visibility

How to reduce carrying costs on Shopify without creating stockouts

Reducing carrying costs is not the same as ordering less of everything. That route trades an overstock problem for a stockout problem. The goal is precision: ordering the right quantity at the right time, for each SKU individually.

• Calculate days-of-supply per SKU, not just units-on-hand. A product with 500 units but 600 days of supply is overstock. A product with 50 units but 6 days of supply is a pending stockout. The number alone tells you nothing without velocity context.
• Rank slow movers by capital-at-risk, not just quantity. A high-value SKU with 200 days of supply ties up far more cash than a low-cost one with the same days-of-supply. Prioritize clearance by dollar value frozen, not unit count.
• Resist "just-in-case" buying without data to back it. Supply chain variability is real (Netstock's 2025 research found lead-time variability was the top challenge for 68% of businesses), but blanket buffer buying amplifies carrying costs across your entire catalog.
• Tie reorder quantity to your actual carrying cost rate. If your rate is 25%, the cost of holding an extra month of safety stock on a $10,000 SKU is roughly $208. Weigh that against the cost of a stockout before you over-buffer.
• Review turnover by category quarterly. A healthy inventory turnover for most Shopify stores is 4-8 turns per year. SKUs turning fewer than 2 times annually are almost always carrying cost problems waiting to be named.

This is where a tool with transparent, per-SKU math earns its place. Stockcast: Inventory Forecast surfaces dead-stock flags and days-of-supply rankings daily, so you can see exactly which SKUs are silently accumulating carrying costs before the quarterly stocktake reveals the damage. Every recommendation shows the underlying calculation, not just a colored dot.

The bulk-discount trap: when saving per unit increases total cost

One of the most common ways Shopify merchants accidentally inflate carrying costs is by accepting a supplier's bulk discount without running the full math. The logic feels sound: lower unit cost means higher margin. But it ignores what happens to the units that do not sell for six months.

A simple test: if the discount saves you $X on a larger order, but the additional carrying cost of the extra units exceeds $X over their expected holding period, the discount is a net loss. For a worked example of this calculation in a real purchase order context, see our supplier and PO case studies.

FAQ

What is a good carrying cost percentage for a Shopify store?

Most multi-channel ecommerce businesses maintain carrying costs between 18% and 30% of inventory value annually. Rates below 18% typically indicate efficient inventory turnover or lower-risk product categories like durable hard goods. Rates above 30% usually signal excess stock, slow-moving SKUs, or high-risk categories like electronics or fashion that need tighter reorder controls.

How do I calculate the carrying cost of a single SKU?

Multiply the unit cost by your carrying cost percentage, then divide by 12 to get a monthly holding cost per unit. For example, a product that costs $50 at a 24% annual carrying rate costs $1.00 per unit per month to hold. Multiply by units on hand to see the total monthly drag from that SKU.

Is it better to have lower inventory to reduce carrying costs?

Not universally. The goal is not minimal inventory but optimal inventory: enough to fill demand without excess. Cutting stock too aggressively creates stockouts, which carry their own cost in lost sales and customer churn. The right lever is improving the accuracy of reorder timing and quantity, so safety stock is calibrated to actual lead time and demand variability rather than a rough guess.