Free tools
Inventory calculators
6 free inventory calculators: safety stock, reorder point, EOQ, inventory turnover, GMROI and days of cover. Each shows the formula and the working.
Safety stock calculator
Safety stock is the extra inventory you hold to cover swings in demand and supplier lead time. This calculator uses z × √(lead time × σ² of demand + demand² × σ² of lead time).
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Reorder point calculator
The reorder point is the inventory level at which you place a new order: demand during the supplier lead time plus safety stock.
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EOQ calculator
Economic order quantity is the order size that minimises the combined cost of placing orders and holding stock: EOQ = √(2 × annual demand × cost per order ÷ holding cost per unit).
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Inventory turnover calculator
Inventory turnover is cost of goods sold divided by average inventory at cost. It shows how many times you sell through your stock in a period; days of inventory is the period divided by turnover.
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GMROI calculator
GMROI, gross margin return on inventory investment, is gross margin divided by average inventory at cost. A GMROI of 2.0 means each dollar of inventory returned two dollars of gross margin.
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Days of cover calculator
Days of cover is the number of days current stock will last at the current rate of sale: (on hand + on order) ÷ daily velocity.
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Calculations run in your browser and nothing you enter is sent anywhere. New to the terms? See the glossary.
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