📅 Free Supply Chain Tool

Days of Inventory (DOI),
The Most Overlooked Supply Chain KPI

Days of Inventory (DOI) tells you how many days your current stock will last at current consumption rates. Most SMEs never calculate it, and it shows.

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📊 DOI & DSI
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Days of Inventory Calculator

Days of Inventory (DOI) Calculator

Calculate your Days of Inventory Outstanding (DOI) and Days Sales of Inventory (DSI) to understand how long your current stock will cover demand.

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Total stock value at cost price
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Annual COGS from your accounts
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Total annual sales revenue
Days of Inventory Results
Days of Inventory (DOI)
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Days current stock will last
Days Sales of Inventory (DSI)
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Based on revenue
Industry Benchmark
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Target range for your sector
DOI vs Benchmark
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Days above or below target

Days of Inventory Formula

DOI = (Inventory Value / COGS) × 365
DSI = (Inventory Value / Revenue) × 365

DOI uses COGS for a cost-basis view • DSI uses revenue for a sales-velocity view • Both are valid KPIs

What Is Days of Inventory?

Days of Inventory (DOI), also called Days Sales of Inventory (DSI) or Days Inventory Outstanding (DIO), measures how many days your current stock will last before it runs out, assuming current consumption or sales rates continue. It is one of the most important supply chain KPIs, and one of the least commonly tracked by Pakistan SMEs.

Why DOI Is the KPI Nobody Talks About

A business with 180 days of inventory has six months of cash tied up in stock. At a 25% annual holding cost rate, that is 12.5% of inventory value spent on carrying costs alone. Reducing DOI from 180 to 90 days would release 50% of working capital and halve holding costs without impacting service levels, if done properly.

DOI vs Inventory Turnover Ratio

DOI and inventory turnover ratio (ITR) are inverse measures. An ITR of 4 equals 91 days of inventory. An ITR of 6 equals 61 days. DOI is more intuitive for operations teams because it speaks in days rather than a ratio. Use both, they tell the same story from different angles.

What is a good DOI for a Pakistan manufacturing SME? ▼
It depends heavily on your industry and supply chain structure. FMCG businesses typically target 30-45 days. General manufacturing 45-75 days. Industrial and engineering businesses with long-lead-time imported components often carry 90-120 days of stock. The key is benchmarking against your own industry, not across sectors.
How do I reduce Days of Inventory? ▼
Start by running an ABC analysis to identify which SKUs are carrying disproportionate days of stock. Focus on A items first. Then review safety stock levels, reorder points, and minimum order quantities for your highest-DOI items. Eliminating dead stock (items with zero movement in 12+ months) often provides the fastest reduction.
Can DOI be too low? ▼
Yes. Very low DOI creates stockout risk, especially when lead times are long or variable. The right DOI balances working capital efficiency against service level risk. Use the Safety Stock and Reorder Point calculators alongside this tool to find the optimal balance for your specific situation.
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