Zeta Ae Math Journal Volume 10 Number 1.
May 2025, pp.
E-ISSN: 2579-5864 P-ISSN: 2459-9948
D https://doi.
org/10.
31102/zeta.
Application of Economic Production Quantity (EPQ) Method and Just in Time Method (JIT) in Bread Raw Material Inventory Control Teshi Amelia Hakilla Kisty1.
Elfira Safitri*.
Sri Basriati1.
Mohammad Soleh1 Mathematics Study Program.
Faculty of Science and Technology.
Sultan Syarif Kasim Riau State Islamic University.
Indonesia * Corresponding AuthorAos Email: elfira.
safitri@uin-suska.
ABSTRACT
Retno bakery Bread Shop is one of the shops that produces various types of bread.
This bakery has not used a inventory control system in the production process so it cannot meet customer needs.
For this reason.
Retno Bkery Bakery needs to control inventory so that the company's performance and profits are more This study discusses the control of the inventory of each bread raw material such as flour, sugar, milk, yeast, salt, butter and eggs.
The purpose of this study is to obtain the results of the total cost of bread raw material inventory using the Economic Production Quantity (EPQ) method and the Just in Time (JIT) method as well as the comparison of the two methods used.
The methods used are the Economic Production Quantity (EPQ) and Just in Time (JIT) methods.
Based on the results of the study, the percentage difference in cost for each raw material was obtained using the Economic Production Quantity (EPQ) method and the Just in Time (JIT) method, namely for flour raw materials of 42.
05%, sugar 47.
31%, milk 51.
63%, yeast 83%, salt 47.
65%, butter 51.
38% and eggs 51%.
Thus, the Just in Time (JIT) method results in a smaller total cost than the Economic Production Quantity (EPQ) method.
Keywords:
Economic Production Quantity (EPQ).
Just in Time (JIT).
Inventory Control.
Retno Bakery Shop.
Info article:
Submitted: August 2, 2024 Accepted: April 28, 2025 How to cite this article:
Kisty.
Safitri.
Basriati.
, & Soleh.
Application of the Economic Production Quantity (EPQ) Method and the Just in Time (JIT) Method in Controlling Bread Raw Material Inventory.
Zeta Math Journal, 10.
, 110.
https://doi.
org/10.
31102/zeta.
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-ShareAlike 4.
0 International License.
Zeta Ae Math Journal.
Vol.
No.
1, pp.
30 - 38.
Mei, 2025.
INTRODUCTION
Every company in optimizing its production process must be able to control inventory control.
When there is an excess of inventory, it will increase maintenance and storage costs and experience the risk of damaged raw materials, while when there is a lack of inventory, the company cannot meet customer needs.
One of them happened to the Retno Bakery Shop which did not use an inventory control system, so it was necessary to carry out inventory control for the production process at the bakery.
The problem that often arises in inventory control is the ineffectiveness and efficiency of inventory due to excess inventory which results in losses, accumulation of raw materials, etc.
On the other hand, if there is a shortage of raw material inventory stocks, it will result in not being able to meet consumer demand (Andrean.
Fendy.
S and Nugroho.
A, 2.
So that to optimize the supply of raw materials, companies need to control Inventory control is the process of regulating the amount of raw materials stored, storage costs, smooth production and profits obtained (Daud.
N, 2.
Every company must have good skills in managing inventory planning to achieve production process optimization (Lahu.
P, 2.
Inventory is a strategy that companies use to organize, plan, and control the stock of goods according to consumer demand.
The purpose of inventory management is to ensure stock availability, meet customer needs on time, avoid delays in delivery and maintain customer trust to increase satisfaction (Affandi.
P, 2.
Some of the methods used for inventory control include the Economic Production Quantity (EPQ) method and the Just In Time (JIT) method.
The EPQ method is an inventory management model developed for situations where goods or products are produced on a large scale, meaning that the amount of production must be more than consumer demand (Mulyana.
Febrianti.
E and Kulsum, 2.
Meanwhile, the JIT method is a method that produces the production of goods in accordance with consumer demand so that it can save costs more efficiently and potentially increase the Company's profits (Wanayumini and Iskandar.
A, 2.
Some previous research related to the Economic EPQ and JIT methods includes research conducted by Pradana.
A and Jakaria.
B in 2020 obtained results by applying the JIT method which produces raw materials according to consumer needs or demands, which can produce a more optimal and efficient total cost compared to using the EOQ method.
Furthermore, the research was conducted by Syahputra.
Dur.
S and Rakhmawati.
F in 2022 explained that the JIT method is more effective and efficient than the method previously used by the company, because it can significantly reduce the cost of storing raw materials.
The next research was by Asmara.
T and Fajar.
Y in 2020 by applying the EPQ method, the company can optimize inventory costs in its production process.
Furthermore, research conducted by Badruzzaman.
H, et al.
in 2017 obtained the results of the EPQ method being more efficient than the method previously used by the company, because it was able to reduce the cost of raw material inventory efficiently.
The next research was conducted by Tipaka.
Paendong.
M and Mongi.
C in 2017 obtained results that by applying EOQ and EPQ methods, companies can reduce inventory But when compared, the EPQ method has proven to be more efficient in minimizing overall costs than the EOQ method.
Thus, companies can optimize inventory more effectively using the EPQ method.
Based on the description above, the author is interested in conducting research on the Application of Economic Production Quantity (EPQ) and Just In Time (JIT) Methods in Controlling Bread Raw Material Inventory with the aim of finding out the total cost of bread raw material inventory using the two methods and comparing the LITERATURE REVIEW 1 Supplies / Inventory Inventory is a strategy carried out by the company to regulate, plan and control inventory so that the inventory owned by the company is balanced with consumer demand with the aim of minimizing the total costs incurred and improving the quality of the goods produced.
In order for inventory to be managed properly, companies should provide materials that are not too much or not too little, therefore inventory control is needed (Juniarti.
T and Luxviyanta.
A, 2.
Teshi Amelia Hakilla Kisty, dkk Application of Economic Production Quantity (EPQ) Method and Just in Time Method (JIT) in Bread Raw Material Inventory Control 2 Metode Economic Production Quantity (EPQ) The EPQ method is a method of development of an inventory model where raw materials are massively produced and used as finished products.
The EPQ method applies that the quantity produced should be more compared to the amount of customer demand.
(Ekawati.
Adytia.
P and Yunita, 2.
The Steps determine the total inventory cost using the EPQ method (Tipaka.
Paendong.
M and Mongi.
C, 2.
Calculating the optimal production rate with the formula:
ycE= Oo ycc ya.
Oeyc.
ya O Number of requests .
ycI O Ordering costs (Rp.
ya O Storage costs (Rp.
ycy O Average production .
ycc O Average demand size .
Calculate the maximum inventory with the formula:
ycc yaycoycaycu = ycE .
Oe yc.
yaycoycaycu : Maximum inventory .
ycE : Optimal production .
Calculate the total cost of inventory with the EPQ method with the formula:
ya ya ycNya = ycE ycI ycoycaycu ya .
TC : Total cost.
3 Method Just In Time (JIT) The JIT method is a method by applying a reduction in costs to prepare inventory so that costs are more economical and efficient (Sholehudin.
M, 2.
The Steps for Completing the JIT method (Widiastuti.
S et al, 2.
Calculate order quantity with formula:
2ycCya ycEO = Oo ya ya : Number of requests .
ya : Storage costs (Rp.
ycC : Booking costs (Rp.
Calculate the optimal number of shipments with the formula:
ya ycu = 2yca yca : Average production of raw materials .
Calculate order quantity with formula:
ycEycu = Ooycu ycu ycE O Calculate the optimal shipping quantity with the formula:
ycE yc = ycuycu Calculating the frequency of ordering raw materials with the formula:
ya ycA= ycEycu Calculating the total cost of inventory using JIT:
Calculate inventory cost with the formula:
ya ycEO ycN O = ycEO ycC 2 ya .
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Calculate the total inventory cost of the JIT method with the formula:
ycNycycnyc = .
cN O ) OoycA
4 RESEARCH METHODS
The type of research used is quantitative research.
The data used in this study is data on bread raw materials at Retno Bakery Bakery.
The stages in conducting research are:
The data used in this study are secondary data obtained through interviews with the owner of the Retno Bakery Bakery, namely bread raw material data from January 2023 to December 2023.
Calculating storage costs and ordering costs for each bread raw material used.
Calculate the Q value of the EPQ method based on Equation .
Calculate the maximum inventory of the EPQ method based on Equation .
Calculate the total cost of EPQ method inventory based on Equation .
Calculate the total cost of JIT method inventory with Steps:
Calculate the optimal quantity based on Equation .
Calculate the optimal number of shipments based on Equation .
Calculating order quantity based on Equation .
Calculating the shipping quantity based on Equation .
Calculating the frequency of bookings based on Equation.
Calculate the total cost of the JIT method based on Equations .
Comparing the total cost of inventory results using the EPQ method and the JIT method.
Analyze and draw conclusions.
RESULTS AND DISCUSSION
Data Description The data used in this study is the inventory of raw materials used to make torn bread at the Retno Bakery Types of raw materials include wheat flour, sugar, milk, yeast, salt, butter, and eggs.
Data on raw material inventory, prices and all costs incurred by the bakery can be seen in Table 1 below:
Table 1.
Raw Material Demand and Bread Production Data Raw Material/month Production Moon Flour Sugar Milk Yeast Salt Mentega Egg Quantity/pcs .
(K.
(K.
(K.
(K.
(K.
Jan-23 Feb-23 Mar-23 Apr-23 May-23 Jun-23 Jul-23 Agt-23 Sep-23 Oct-23 Nov-23 Des-23 Total Average Source: Retno Bakery Bakery, 2023 Teshi Amelia Hakilla Kisty, dkk Application of Economic Production Quantity (EPQ) Method and Just in Time Method (JIT) in Bread Raw Material Inventory Control The fees incurred by the bakery include the cost of ordering and storage costs.
For ordering costs, which can be seen Table 2 below:
Table 2.
Ordering Costs in rupiah Type of Cost Cost/Month Cost/Year Telephone Unloading Delivery Total Source: Retno Bakery Bakery, 2023 After the goods arrive at the bakery, the store stores them in a storage warehouse.
For storage cost can be found in the following Table 3:
Table 3.
Storage Cost in rupiah Type of Cost Cost/Month Cost/Year Electricity Costs Rent a Shophouse Total Source: Retno Bakery Bakery, 2023 Based on Table 2, the cost of ordering at a bakery in a year is Rp.
17,160,000, bakeries make two different types of orders.
As for the first type of order, the order for flour, sugar and salt is done every week, which means that if there are 48 orders in a year.
Meanwhile, the second type of order is ordering milk, yeast, butter and eggs every 15 days, which means that if there are 24 orders in a year.
2 Inventory Cost Calculation The ordering cost for one order can be obtained by the following Steps:
Calculate the cost of message obtained:
ycNycuycycayco ycCycyccyceyc yaycuycyc Message costs = ycNycuycycayco ycCycyccyceyc yaycyceycycyceycuycayc Rp.
= ycIycy.
So, the order cost for one order is Rp.
Calculating the cost of ordering flour, sugar and salt based on Table 2:
ycuycuyce ycycnycoyce ycuycyccyceycycnycuyci yceyceyce Message costs = yaycuycyc ycuyce ycycayc ycoycaycyceycycnycaycoyc Rp.
= ycIycy.
So, the order cost for flour, sugar and salt is Rp.
444 for one order.
Calculating the cost of ordering milk, yeast, butter and eggs based on Table 2:
ycuycuyce ycycnycoyce ycuycyccyceycycnycuyci yceyceyce Message costs = yaycuycyc ycuyce ycycayc ycoycaycyceycycnycaycoyc Rp.
= ycIycy.
So, the order fee for milk, yeast, butter and eggs is Rp.
583 for one order.
Calculating the storage cost per unit of raw materials based on Table 3:
ycNycuycycayco ycycycuycycayciyce ycaycuycycyc Storage Costs = ycNycuycycayco ycycayc ycoycaycyceycycnycayco ycyceycycycnycyceycoyceycuycyc Rp.
= ycIycy.
311/kg.
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So that the cost of inventory of each raw material can be written into the following Table 4:
Table 4.
Inventory Cost Data Raw Storage Costs Ordering Costs Materials (Rp/K.
(Rp/K.
Flour Rp.
IDR 79.
Sugar Rp.
IDR 79.
Milk Rp.
IDR 59.
Yeast Rp.
IDR 59.
Salt Rp.
IDR 79.
Butter Rp.
IDR 59.
Egg Rp.
IDR 59.
3 Solutions using Economic Production Quantity (EPQ) The following are the steps to determine the total inventory cost of each raw material using the EPQ Flour Raw Material It is known that the total demand for flour (D) is 53,651 kg and the average demand for flour .
as much 471 kg, then:
ycEycyceycyycycuyci 2yaycI =Oo ycc ya.
Oeyc.
cIycy.
= Oo ycIycy.
Oe17.
= 6.
045 kg.
So, the optimal production rate of flour in one period is 6.
045 kg.
Next, calculating the maximum inventory is obtained:
ycc yaycoycaycu = ycE .
Oe yc.
= 6.
Oe 17.
= 4.
534 kg.
So, the maximum supply of flour obtained in one period is 4.
534 kg.
So that the total cost of inventory is obtained:
ya ya ycNya = .
cE ycI) ( ycoycaycu y.
= ( 6.
045 ycIycy.
( 2 ycIycy.
= Rp.
So, the total cost of flour inventory for one period is Rp.
124,-.
For the calculation of raw materials for sugar, milk, yeast, salt, butter and eggs, the same calculation is carried out which can be seen in Table 5 below:
Raw Materials Gula Milk Ragi Salt Mentega Egg Table 5.
Total Raw Material Inventory Cost Optimal Production Rate Maximum Inventory (K.
(K.
Total Inventory Cost (R.
Teshi Amelia Hakilla Kisty, dkk Application of Economic Production Quantity (EPQ) Method and Just in Time Method (JIT) in Bread Raw Material Inventory Control 4 Solutions using Just In Time (JIT) The following are the steps to determine the total inventory cost of each raw material using the JIT Flour Raw Material It is known that the total demand for flour (D) is 53.
651 kg, so:
ycEO 2ycCya =Oo ya =Oo 2.
= 5.
231 ycoyci.
So, the minimum order quantity of flour in one period is 5.
231 kg.
Furthermore, calculating the optimal number of deliveries is obtained:
ya ycu = 2yca = 2.
= 1,497 OO 1 time.
So, the result is obtained as a result of the optimal number of flour shipments 1 time.
Furthermore, calculating the order quantity, delivery quantity and frequency of ordering flour raw materials is ycEycu = Ooycu ycu ycE O = Oo1,497 ycu 5.
= 6.
400 kg.
So, the result of the quantity of flour orders for one period is 6.
400 kg.
= ycuycu
= 1,497
= 4.
275 ycoyci.
Thus, it was obtained that the optimal quantity of flour delivery was 4.
275 kg.
ya ycA =ycE ycu = 6.
= 8,38 OO 8 time.
So, the optimal frequency of ordering flour raw materials is 8 times.
So that the total cost of inventory is obtained:
To calculate the cost of flour inventory, the following formula is used:
ya ycEO ycNO = OycC ya ycE = 5.
= ycIycy.
439 ycIycy.
= ycIycy.
From the total cost of the value is then calculated using the following JIT method:ycIycy.
ycNycycnyc = .
cN O ) OoycA .
cIycy.
Oo8 = ycIycy.
So, the total cost of flour inventory for one period is Rp.
182,-.
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Mei, 2025.
For the calculation of raw materials for sugar, milk, yeast, salt, butter and eggs, the same calculation is carried out which can be seen in Table 6 below:
Table 6.
Total Raw Material Inventory Cost Order Number of Order Shipping Order Total Raw Quantity Shipments Quantity Quantity Frequency Inventory Materials (K.
Cost (R.
Gula Milk Ragi Salt Mentega Egg After calculating using the Economic Production Quantity (EPQ) and Just In Time (JIT) methods, the following results were obtained:
Table 7.
Comparison of Total Costs of Both Methods in rupiah/one message Raw
Total Cost
Percentage of Total Cost
EPQ
JIT
Materials Difference Difference Tepung
42,05%
Gula
47,31%
Milk
51,63%
Ragi
51,83%
Salt
47,65%
Mentega
51,38%
Egg Based on Table 7, it can be seen that the total cost result using the Just In Time (JIT) method has a smaller cost compared to using the Economic Production Quantity (EPQ) method.
CONCLUSION
Based on the discussion, it can be concluded that the total cost using the Economic Production Quantity (EPQ) method for flour raw materials is IDR.
124, sugar IDR.
345, milk IDR.
761, yeast IDR.
834, salt IDR.
618, butter IDR.
978 and eggs IDR.
Meanwhile, the Just In Time (JIT) method for flour raw materials amounted to IDR.
182, sugar IDR.
563, milk IDR.
378, yeast IDR.
971, salt IDR.
877, butter IDR.
442 and eggs IDR.
424 with the percentage difference in cost for each raw material, namely for flour raw materials of 42,05%, sugar 47,31%, milk 51,63%, yeast 51,83%, salt 47,65%, butter 51,38% and eggs So that the total cost of inventory of each raw material using the Just In Time (JIT) method is more optimal than the Economic Production Quantity (EPQ) method.
BIBLIOGRAPHY