Days of Cover
Also known as: DOC, Days of Stock, Inventory Days on Hand
How many days your current inventory will last at recent sales velocity — the most useful number on your inventory dashboard.
Days of Cover (DOC) is the number of days your current on-hand inventory will last given recent sales velocity. The formula is DOC = on-hand units / average daily sales. A SKU with 100 units on hand selling 10/day has 10 days of cover.
Why DOC is the most useful inventory metric: it abstracts away absolute unit counts and converts everything to a single time-based number that's directly comparable across SKUs. A SKU with 1,000 units of cover can wait. A SKU with 12 days of cover and a 14-day lead time is already late on the reorder. DOC turns the question "do I have enough?" into "do I have enough TIME?"
A good restock workflow ranks SKUs by DOC ascending and processes the lowest-DOC items first. SellerVault's Restock Planning page does exactly that, with the addition of capacity-limit awareness and case-pack rounding. Spreadsheet-based restock workflows usually skip DOC entirely and that's why they miss stockouts on fast movers.
You have 240 units of a SKU on hand. Average daily sales over the last 30 days is 8 units. DOC = 240 / 8 = 30 days. Your supplier lead time is 21 days, so you have 9 days of buffer before you need to ship in your next order — before factoring in safety stock.
DOC-driven restock recommendations
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