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Stock Cover Calculator

Work out how many days your current stock will last at today’s demand.

Days of cover is the runway metric. Units on hand tell you nothing on their own — 1,800 units is a year of stock for one item and four days for another. Cover converts the quantity into the only unit that matters operationally: time before you run out.

Days of cover

How long on-hand stock lasts before it runs out at current demand.

Weeks of cover
Days of cover incl. on order

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Your numbers

units
units/day
units

Confirmed purchase orders not yet received.

The formula

Days of cover = On-hand ÷ Average daily demand

Add stock already on order to see how far the incoming delivery pushes the runway out.

What it means

Days Inventory Outstanding — full definition

Read in the glossary

How to use it

  1. 1

    Count only sellable on-hand stock. Quarantined, damaged and allocated units are not cover.

  2. 2

    Use recent daily demand — the last four to eight weeks — rather than a long-run average that smooths away the trend you are trying to see.

  3. 3

    Compare the result to lead time. Cover below lead time means the stockout is already booked; the order simply cannot arrive in time.

Where it goes wrong

  • Cover measured against a stale demand rate is worse than no metric at all. A line whose demand has doubled will show comfortable cover right up until the day it empties.

  • Very high cover is a cash problem, not a safety achievement. Anything above 120 days on a non-seasonal item deserves a look for slow-moving or dead stock.

Worked example

When cover is shorter than lead time

1,800 units on hand against 40 units a day is 45 days of cover — comfortable. But if that same item sold at 200 units a day, cover collapses to 9 days. With a 14-day supplier lead time, the stockout is unavoidable: the only remaining decisions are which customers to disappoint and whether to pay for air freight.

Common questions

How is days of cover different from DIO?

DIO is a backward-looking financial average across a whole portfolio. Days of cover is forward-looking and per item, driven by current on-hand and current demand — it is the operational version of the same idea.

How much cover should I target?

At minimum, lead time plus your review period plus a buffer. Below that you are relying on luck; far above it you are financing stock that could be cash.

Should I include stock in transit?

Track it separately, as this calculator does. On-hand cover tells you when you run out; cover including on-order tells you whether the fix is already in motion.

Let AWRA do this on your live data

This calculator works on one set of numbers. AWRA OpsHub keeps stock cover calculator results current across every item, supplier and location — automatically.