Stock Holding Period Calculator for Ecommerce

Calculator Inputs

Period Days

Opening Stock Units

Closing Stock Units

Opening Stock Value ($)

Closing Stock Value ($)

Received Units During Period

Units Sold

Cost of Goods Sold ($)

Sales Revenue ($)

Storage Cost per Month ($)

Insurance Cost per Month ($)

Handling Cost per Month ($)

Financing Rate per Year (%)

Obsolescence Rate per Year (%)

Target Holding Days

Example Data Table

SKU	Opening Units	Closing Units	Units Sold	COGS ($)	Holding Period (Days)	Turnover	Status
Bluetooth Earbuds	1,000	650	850	18,700.00	59.56	1.51x	Slow moving stock
Phone Cases	2,200	1,500	2,100	14,200.00	58.63	1.54x	Slow moving stock
Smart Watches	500	420	260	14,300.00	144.76	0.62x	High overstock risk

Use the sample rows to compare fast, balanced, and aging inventory behavior across ecommerce products.

Formula Used

1. Average Inventory Value
(Opening Stock Value + Closing Stock Value) ÷ 2

2. Stock Turnover Ratio
Cost of Goods Sold ÷ Average Inventory Value

3. Stock Holding Period
Period Days ÷ Stock Turnover Ratio
This is equivalent to:
Average Inventory Value ÷ Daily COGS

4. Sell Through Rate
Units Sold ÷ (Opening Units + Received Units) × 100

5. GMROI
(Sales Revenue − Cost of Goods Sold) ÷ Average Inventory Value

6. Total Carrying Cost
Monthly Storage, Insurance, and Handling Costs for the period
+ Average Inventory Value × (Financing Rate + Obsolescence Rate) × (Period Days ÷ 365)

How to Use This Calculator

Enter the review period in days.
Fill opening and closing stock units and values.
Add received units, units sold, COGS, and revenue.
Enter monthly storage, insurance, and handling costs.
Enter annual financing and obsolescence rates.
Add your target holding days for performance comparison.
Press Calculate Holding Period.
Review the result cards, detailed table, and Plotly graph.
Use the CSV or PDF buttons to export the result.

FAQs

1. What does stock holding period mean?

It shows how many days inventory stays in stock before it is sold. Lower values usually mean faster turnover and less capital tied up.

2. Why use value-based holding days instead of units only?

Value-based holding days connect inventory directly to COGS and working capital. That makes the result more useful for cash flow and profitability decisions.

3. What is a good holding period for ecommerce?

It depends on product category, seasonality, margin, and supplier lead time. Fast fashion and electronics usually need shorter holding periods than durable or niche products.

4. How does carrying cost affect decisions?

High carrying cost means inventory is consuming cash through storage, insurance, financing, and obsolescence. That often signals overbuying or slow movement.

5. What is GMROI in this calculator?

GMROI measures gross margin earned for each dollar invested in average inventory. Higher GMROI usually indicates better stock productivity and merchandising efficiency.

6. Can I use this for seasonal products?

Yes. Use a period that matches the season, campaign, or collection cycle. Seasonal items often need separate reviews from evergreen stock.

7. Why is sell through rate included?

Sell through rate helps explain whether inventory movement is healthy relative to available units. It complements holding days by showing demand strength.

8. When should I reorder after reviewing the result?

Reorder when projected stock cover approaches supplier lead time plus safety stock. Do not rely on holding days alone for purchasing decisions.

Advanced Stock Holding Period Calculator