From your books
Length of the period
A year (365 days)
$
From your profit and loss. Use cost, not the selling price.
$
At cost, from the balance sheet on the first day.
$
Turnover
Average inventory
(Start + end) ÷ 2
$40,000.00
Inventory turnover
Cost of goods sold ÷ average inventory
6.00 times
Days inventory outstanding
Days in the period ÷ turnover: how long stock sits before it sells
60.8 days
Weeks of stock on hand
8.7 weeks
What counts as good depends on what you sell: a grocer may turn stock 15 times a year, a furniture or hardware store 3 or 4. Compare with your own past periods first. Use the same cost method (FIFO or average) for both inventory figures.