Economic Order Quantity: It is an amount of stock
ordered which minimises the total cost of production or we can say minimise the
ordering cost and carrying cost.
Assumptions:
·
The lead time is constant.
·
The demand rate remains constant and evenly spread throughout
the year.
·
The ordering cost and carrying cost remain constant and it
doesn’t change with change in ordered quantity.
·
There is only two cost involved in inventory that is ordering
cost and carrying cost.
Formula:
Q = √ ((2*D*S)/ H)
N= D/ Q
N= D/ Q
Annual holding
cost = H * (Q / 2)
Annual
Ordering cost = S * (D / Q)
∆π = D * d + [(D / Q EOQ)
– (D / Q DO)] S – [((Q DO – (P-d) H)/ 2) – ((Q EOQ
* P*H)/ 2)]
Where,
Q =
Economic order quantity
D =
Annual demand or sales
S =
Order cost
P =
Price per unit
∆π = Change in profit
d= Discount
amount
Q
EOQ = economic
order quantity
Q
DO = Discount offered in that quantity
H =
holding cost per unit or carrying cost
N =
Number of expected order
The
two costs involved in this equation that is ordering cost and carrying cost. In
which the carrying cost include other cost also like transportation cost for
carrying goods from supplier place to ordering company. The handing cost for
unloading the goods and storage cost for keeping the goods in warehouse until
it sold out to customers. The carrying cost also includes the insurance cost
for protecting the goods from theft, fire and flood etc.
Example: Find out the economic order
quantity (EOQ) and number of quantity order with the help of given information:
Particulars
|
Amount (in Rs.)
|
Annual Cost per order
|
7
|
Annual sales
|
10, 000
|
Carrying cost%
|
30
|
Price per unit
|
5
|
Solution:
Q =
√ ((2*D*S)/H)
= √ (2*10, 000*7)/0.30*5
= √ (1, 40,000 / 1.5)
= √93, 333.33
= 305.50
= 306 units
Number of Order
placed (N) = D / Q
= 10, 000 / 306
= 32.67 or 33
Quantity ordered
= 10, 000 / 33
= 303
The total annual costs
of placing 33 orders are:
Annual carrying
cost =1.5 *(303 / 2)
= Rs. 227.25
Annual ordering
cost = 7 * (10,000 / 303)
= 7 * 32.67
= 231
Total cost = 227
+ 231
= Rs. 458
Example:
Find out the optimum order quantity from the given information:
Particulars
|
Amount (in Rs.)
|
Annual usage or demand
|
8, 000
|
Carrying cost per unit
|
12%
|
Ordering cost per unit
|
20
|
Discount rate per unit
|
10
|
Price per unit
|
32
|
Discount available in given quantity: 200 and
400 units.
Solution:
Q
= √ ((2*D*S)/H)
= √ ((2*8, 000*20)/32 * 0.12)
= √ (3, 20,000/3.84)
= √ 83, 333.33
= 288.67 or 289
units
The discount available
in 200 units is < economic order quantity 289 units. So, the optimum order quantity
is equal to economic order quantity i.e. 289.
∆π = D * d + [(D / Q EOQ) – (D /
Q DO)] S – [((Q DO – (P-d) H)/ 2) – ((Q EOQ * P*H)/
2)]
=
8, 000 *10 + [(8, 000 / 289) – (8, 000 / 400)] 20 – [((400 – (32-10) 0.12)/ 2) –
(289 * 32*0.12/ 2)]
=
80, 000 + [27.68 – 20] 20 – [198.68 – 554.88]
= 80, 000 + 160 +356
=Rs. 80, 516
The profit amount shows that the optimum order quantity is 400
units in place of 289 units. But if there is a negative amount then the EOQ
will be 289 units because it shows loss for the company.
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