Free calculator
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.
- Days of cover (on hand + on order)
- 20 days
- Days of cover (on hand only)
- 20 days
- Daily velocity
- 30 units/day
- Gap before a new order could arrive
- 15 days without stock if you order today
Compares on-hand cover with the lead time.
Working
- Daily velocity: 900 ÷ 30 = 30 units/day
- Days of cover: (600 + 0) ÷ 30 = 20 days
Runs in your browser; nothing you enter is sent anywhere. Results are estimates from the numbers you provide.
The formula
Days of cover = (on hand + on order) ÷ (units sold ÷ days in window)
How it works
Velocity is units sold per day over a recent window. Thirty days suits steady products; fast movers and new launches suit shorter windows, and seasonal products need a forecast instead of a trailing average.
Comparing days of cover on hand with the supplier lead time shows whether you will run out before a new order could arrive. If on-hand cover is shorter than lead time, a gap is already baked in.
Worked example
600 units on hand and 900 sold in 30 days is 30 units a day, so 20 days of cover. With a 35-day lead time, ordering today still leaves a 15-day gap.
Watch out for
- A trailing average misses upcoming promotions, seasons and trends. Check the window against what is coming.
- Do not count stock that is damaged, reserved for other orders or held in a location you cannot sell from.
Frequently asked questions
How many days of cover should I hold?
Is days of cover the same as days of inventory?
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Stokrio runs these calculations for every product, using your own sales and supplier lead times.