Inventory Days Coverage & Reorder Frequency Calculator
Free inventory days coverage calculator. Instantly calculate how long your inventory will last and how often to reorder using lead time and daily usage.
Inventory days coverage calculator (days of inventory)
Reorder frequency formula based on lead time
How long will my inventory last?
Inventory days coverage tells you how many days your current stock will last at your average usage rate. It is a key metric for operations and supply chain planning. The formula is:
Days Coverage = Current Inventory ÷ Average Daily Usage
Reorder frequency tells you how often you should place orders to avoid running out of stock, based on your lead time and coverage. The formula is:
Reorder Frequency = Days Coverage ÷ Lead Time
Example: If you have 500 units in stock, use 50 units per day, and your lead time is 7 days, your inventory will last 10 days. You should reorder every 0.7 lead times to avoid stockouts.
Frequently Asked Questions
Divide your current inventory by your average daily usage. This gives you the number of days your stock will last at the current rate.
Reorder when your days of coverage is less than your lead time, or use the reorder frequency formula to plan regular orders and avoid stockouts.
Longer lead times require more inventory coverage to avoid stockouts. Always ensure your coverage exceeds your lead time for smooth operations.
If your average daily usage increases, your days of coverage will decrease. Update your numbers regularly for accurate planning.
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