“We’ve worked
hard to improve our inventory turn, and we’ve made progress,
but now we seem to be stuck. We know we should be able to
turn our inventory faster, and get more out of it. Can you
help us?”
Inventory turn can be a powerful
metric for freeing up vital dollars and cents for more
productive purposes.
by Ted Hurlbut
Hurlbut & Associates
Introduction
As a business
metric, inventory turn is understood to be the key starting
point for measuring inventory productivity. Inventory turn
is the critical first piece of data for evaluating
operational efficiencies and the freshness of the inventory.
But underlying the concept of inventory turn is the fact
that there is real money involved, and that inventory turn
is a powerful metric for driving inventory reduction and
freeing up those dollars and cents for more productive
purposes.
There’s no such
thing as standing still in a dynamic business and economic
environment. If you’re not going forward, you’re most likely
going backward. It’s especially true in inventory
management. Those companies that are not continually seeking
to improve the productivity of their inventory by increasing
inventory turnover are likely to see more and more of their
dollars and cents tied up in an increasingly unproductive
inventory.
The Inventory
Turn Formula To begin to understand the power of inventory
turn, it is important to review how inventory turn is
calculated.
The basic
inventory turnover calculation is as follows:
Cost of
Goods Sold during the past 12 months
Average
Inventory at Cost during the past 12 months .
A couple of quick
notes regarding this formula:
1. Inventory
turnover is a measure of inventory productivity, thus the
cost of sales made from other than inventory on hand, such
as special orders, needs to be excluded from the cost of
goods sold.
2. Inventory
turnover is stated as an annual turnover. However, the
period being measured does not necessarily have to be a 12
month period. In certain situations, particularly for
seasonal items, inventory turn may be measured for a period
of a few months, with the result being “annualized” for
comparison purposes.
3. Average
inventory at cost is usually calculated by averaging the
ending inventories for the past 12 months. However, if
inventory fluctuates greatly from month to month, or even
within months, it may be necessary to calculate the average
inventory using weekly or bi-weekly ending inventory values.
4. Inventory turn
is a dynamic metric. As sales (and thus, cost of goods sold)
and inventory levels fluctuate so to does inventory turn. It
is not enough to measure inventory turn for each year or
quarter. At a minimum, in order to properly utilize
inventory turn as a tool it is necessary to measure it
monthly on a rolling basis.
The Power of
Inventory Turn
To fully
illustrate the power of inventory turnover to identify
opportunities to free up cash for other purposes, there is a
basic assumption which needs to be explicitly stated. The
cost of goods sold is an integral component of the inventory
turn formula. In illustrating the power of inventory
turnover, the cost of goods sold will be held constant over
a range of inventory levels.
In a real world
situation, this assumption is obvious. As inventory is
reduced, those reductions will not have the effect of
reducing sales, or, by extension, cost of goods sold (an
implicit secondary assumption is that gross profit margins
remain constant, as well). The point of inventory reduction
is to liquidate non performing inventory and eliminate
overstocks of on-going items, not to create out-of-stocks
which will directly impact sales.
To illustrate the
power of inventory turnover, let’s consider a fictitious
company, XYZ Corp. Let’s start by assuming that XYZ’s annual
cost of goods sold is $25.0 million, and hold that constant.
Let’s also start by assuming that XYZ’s average annual
inventory is $10.0 million. That will yield an annual
inventory turnover of 2.5 times. Translated into average
weeks of supply on hand, an annual inventory turnover of 2.5
times is equal to 20.8 weeks of supply on hand (52 weeks/2.5
turns).
Annual Inventory
Turnover
Annual Cost of Goods Sold (000's)
Average Inventory On Hand (000's)
Cumulative Savings
Average Weeks of Supply On Hand
2.5
$25,000,000
$10,000,000
N/A
20.8
2.6
25,000,000
9,615,385
$384,615
20.0
2.7
25,000,000
9,259,259
740,741
19.3
2.8
25,000,000
8,928,571
1,071,429
18.6
2.9
25,000,000
8,620,690
1,379,310
17.9
3.0
25,000,000
8,333,333
1,666,667
17.3
3.1
25,000,000
8,064,516
1,935,484
16.8
3.2
25,000,000
7,812,500
2,187,500
16.3
3.3
25,000,000
7,575,758
2,424,242
15.8
3.4
25,000,000
7,352,941
2,647,059
15.3
3.5
25,000,000
7,142,857
2,857,143
14.9
3.6
25,000,000
6,944,444
3,055,556
14.4
3.7
25,000,000
6,756,757
3,243,243
14.1
3.8
25,000,000
6,578,947
3,421,053
13.7
3.9
25,000,000
6,410,256
3,589,744
13.3
4.0
25,000,000
6,250,000
3,750,000
13.0
Now let’s examine
the impact if XYZ were to plan to reduce inventory without
impacting sales (or cost of goods sold). If XYZ were able to
plan the inventory to turn 0.1 turns faster it would equate
to a reduction in inventory of $384,615, or 3.8%. From
an inventory management perspective, XYZ would be planning a
reduction in the average weeks of supply of 0.8 weeks, from
20.8 weeks to 20.0 weeks.
If XYZ were able
to increase the turn over a six month period, for example,
from 2.5 turns to 2.8 turns, it would have the impact of
reducing average inventory on hand from $10.0 million to
$8.9 million, a savings of $1.1 million in average
inventory! An increase in turn from 2.5 times to 2.8 times
translates into a reduction in the average weeks of supply
on hand from 20.8 to 18.6 weeks.
Let’s restate
this: In our example a reduction in average weeks of supply
on hand from 4.8 months (20.8 weeks/4.33) to 4.3 months
(18.6 weeks/4.33) from an inventory base of $10.0 million,
frees up over one million dollars in cash over a six month
period for other important uses!
How can this be
done???
Drilling Down
In our example,
we’ve examined inventory turnover on a company-wide basis.
To fully utilize inventory turn as a tool, however, it is
critical to continually drill down and measure turn at the
division or department level, the product line or category
level, and at the item or SKU level.
Within any
company’s business, there are product lines, categories and
items which, by their nature, turn faster than others. Core
items, with high sales volumes and that sell frequently,
will turn more quickly than other complementary items which
may be rounding out assortments or are offered as a
convenience for customers. Only by evaluating the full range
of product lines, categories and items, and understanding
their sales patterns and inventory requirements can a full
picture of inventory turnover be developed.
For example, in a
pet supply business, pet food might be expected both to
represent a significant percentage of both the sales volume
and transaction count. Customer demand is highly
predictable, so strategies can be developed to shorten lead
times and increased the frequency of replenishment to
minimize the inventory investment at any given moment.
Feeding supplies and dietary supplements might not sell as
frequently or generate as much volume as food, but customers
expect that those items will be in stock whenever they need
them. Other categories such as grooming supplies, feeding
supplies or toys might be expected to represent a less
significant percentage of sales, and their sales pattern
might be more volatile, requiring a relatively greater level
of inventory.
It is only after
fully understanding the sales patterns and inventory
requirements within a business that concrete action plans
can be developed by product line, category and item to
improve inventory turn and reduce the average inventory
investment.
Plan Inventory
Levels and Inventory Turnover In order to reduce inventory
levels, increase turnover inventory productivity, inventory
levels must be planned, from the bottom up, by product line,
category and item. This process begins with a reliable sales
forecast, built from the bottom up, which takes into account
unique sales patterns and characteristics of individual
product lines, categories and items. From these individual
sales forecasts, broken down by week or by month, ending
inventory levels can be developed for each period.
When reviewing
inventory plans, critical questions must continually be
asked for each and every product line, category and item.
How do planned inventories compare to last year’s actual
inventories? Were last year’s inventories too little, too
much, or just about right? Are there opportunities this year
to reduce lead times, which would enable inventories to be
reduced compared to last years levels? Were sales less
volatile than anticipated, which would enable a reduction in
safety stocks? Were sales in a given category spread out
over too great an assortment, enabling a narrowing of
assortments and a reduction in inventory? Can inventories be
cut back by 2% or 3% or 5% in this product line, category or
item without negatively impacting sales volume?
At the same time,
there must be a real sense of urgency about identifying slow
moving and non performing inventory as quickly as possible
and taking the hard measures necessary to liquidate it. Slow
moving and non performing inventory add little to the top
line, deflect company and customer attention away from
highly productive product lines, categories and items, and
tie up valuable cash that could be used for other important
purposes. As part of the inventory planning process, it is
important to plan the steps necessary to get rid of slow
moving and non performing inventory as quickly as possible.
Conclusion
Inventory turn
can be a powerful metric for freeing up vital dollars and
cents for more productive purposes. Measuring inventory turn
from the bottom up, at the product line, category or item
level, is the first step in building an inventory plan which
eliminates unnecessary inventory and frees up cash.
This bottom up
approach to inventory planning, using inventory turnover as
the critical metric to drive the analysis, can help
companies assure that they are continually pushing the
inventory envelope, keeping inventory levels lean and
inventory productivity high.