Inventory days of supply calculator
How many days your on-hand stock will last.
Formula
Days of supply = (on-hand inventory value ÷ annual COGS) × 365
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Inventory days of supply
50.0
days of supply on hand
Worked example
$740,000 of on-hand inventory against $5,400,000 of annual cost of goods is 50.0 days of supply. Take it to 40 days and you release roughly $148,000 of cash without changing a single price.
When you reach for this
The bridge between an inventory conversation and a cash conversation. Every extra day of supply is working capital sitting in a warehouse instead of in the bank.
How to read the number
A company-wide figure hides the problem. Calculate it per SKU class and you will usually find the average is the midpoint between stock you cannot get and stock you cannot move.
Metrics that travel with it
Questions operators ask about this metric
Should I use cost or retail value?
Cost on both sides. Mixing retail inventory value with cost of goods inflates the day count by your entire margin and makes the position look far worse than it is.
Why does the company-wide number mislead?
It blends two opposite failures into one comfortable-looking average. Split it by SKU class and the overstock separates from the stockouts immediately.
How does this relate to inventory turns?
They are one fact stated two ways: 365 divided by days of supply gives you turns. Days of supply travels better with a planner, turns with a CFO.
What is the right number of days to hold?
Whatever your replenishment lead time plus safety stock requires, which is a supply chain answer rather than an industry benchmark. Holding fewer days than your lead time guarantees stockouts.
Stop calculating this by hand
Every number on this page comes out of data you already have — orders, shipments, inventory, deductions. Endless keeps those in one source of truth instead of four exports, so the metric updates on its own and agents watch it for you.