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There are a number of
measures that get used for tracking inventory performance. One of the most
popular is ‘stock outs’. A ‘stock out’ occurs when there is demand for an
inventory item but there is no stock.
It is essential to
measure the availability of stock, after all that is why the investment is
made in the first place. However, measuring stock outs can be a limiting way
to measure inventory as it only measures one dimension of inventory, that
is, availability. This is limiting because one way to ensure a low number of
stock outs is to over invest in inventory so that stock is always available
no matter what. This is sometimes referred to as ‘just in case’ inventory.
What is a ‘Stock
Turn’?
As inventory requires
a significant financial investment and that investment involves significant
ongoing costs it is also important to measure the financial performance.
Tracking the value of inventory is important for cash management. However,
an additional financial measure that often gets overlooked is the stock turn
ratio.
The ‘stock turn’ is
calculated by dividing the annual usage of the inventory (in dollars) by the
value of the inventory held (also in dollars).
For example, if a
company holds $5M worth of inventory and issues $2.5M worth of that
inventory in a year, the stock turn ratio is 2.5/5.0 = 0.5. That is the
company ‘turns over’ its inventory at the rate of one half per year.
Obviously, the higher the stock turn ratio the better.
What ‘Stock Turns’ Tells Us
Stock turns measures
the efficiency of the inventory investment by telling us whether we have
over invested in inventory and whether we have the right mix of inventory.
(Note however, that it won’t tell us about specific inventory items.)
For example, if the
number of stock outs is low (which is good) and the stock turn ratio is also
low (which is bad) it is an indicator that there may be an over investment
in inventory.
If the number of stock
outs is high (which is bad) and the stock turn ratio is low (which is also
bad) this indicates that we may have invested in the wrong inventory. That
is, that that our money is tied up in stock that doesn’t turn over and we
hold too little of the stock that is in demand.
Stock Turn Targets
An appropriate target
for stock turns in your business will be influenced by a range of issues,
some within your control and others outside of your control. For example, if
you have spares that are imported from somewhere far away or you are in a
remote and isolated area then you are likely to hold more safety stock and
therefore have a lower stock turn. If your processes don’t adequately
control decision making on inventory stocking you are also likely have a low
stock turn. The book
Smart
Inventory Solutions details the 12 reasons why companies may
hold more inventory than they really need.
Using ‘Stock Turns’ as a Key
Measure
The key thing to remember when using a stock
turn ratio is that it must be applied across the entire inventory. You
cannot ‘cherry pick’ elements of inventory. The reason for this is that some
inventory items will naturally have a high turn over and some will be low.
The aim of the ratio is to measure the overall efficiency of the inventory
investment.
In one recent case an inventory manager tried
to justify the size of his inventory by pointing out that one section of
inventory had a stock turn of 5 (very good in his circumstance) and that
another section had a stock turn of 0.2 (very bad). The justification was
that insurance spares caused the low stock turn and therefore nothing
further could be done. This analysis, however, ignored a large component of
inventory that could be managed down and it ignored the possibility of
consignment stock for the fast movers.
‘Stock turns’ is also
a great measure to use when you have multiple sites or locations within the
one company. As an internal benchmark, stock turns readily shows which sites
have better control over their inventory.
‘Stock turns’ is an
essential measure of inventory performance because it measures the inventory
efficiency. When used in conjunction with other measures such as stock outs,
the overall performance of your inventory investment can be determined.
About The Author
Phillip Slater is the
author of the book
Smart
Inventory Solutions and the developer of the
Inventory
Cash ReleaseTM System - ICRTM06, a world’s best practice
approach to inventory management and reduction.
For more information visit
his website at
http://www.InitiateAction.com.
Note:
You are welcome to reprint this article online on the condition that it
remains complete and unaltered (including the ‘About the author’ info at the
end) and you send a reprint to
enquiries@InitiateAction.com
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