Tuesday, December 26, 2006

Purchasing and Inventory Management

I hope that you have enjoyed the article "Purchasing & Inventory Management Hook Up!" As promised in that article, here's the EOQ formula:
Where:

EOQ = Economic Order Quantity

ACPO = Acquisition Costs Per Order

AUU = Annual Usage in Units

UC = Unit Cost

CCP = Carrying Cost Percentage


So, if you know that it costs you $150 in overhead per order, you use 5,000 widgets a year, you pay $200 per widget, and your Finance Department tells you that annual carrying costs are equal to 20% of the value of the goods in stock, you should order...


Drumroll please...


194 widgets at a time.

I don't often place a link to this blog in my purchasing articles, so if you are reading this blog for the first time, please browse the posts below - I think you'll like them. I post educational and purchasing-related blurbs here about three times per week, so you may want to plan regular visits to this blog. Just remember to go to http://www.NextLevelPurchasing.com/blog, bookmark this page, or, if you're a techie, add this blog to your RSS feed reader using the Site Feed link to the right.

Hope to "see" you back here soon!

To Your Career,
Charles Dominick, SPSM
President
Next Level Purchasing, Inc.
Struggling To Have A Rewarding Purchasing Career?
Earn Your SPSM Certification Online At
http://www.NextLevelPurchasing.com

52 Comments:

At 1:20 PM, Anonymous rita said...

I found your equation very interesting and as a lean thinker I'm trying to see if I can validate it. I'm a little confused about the definition of ACPO = Acquisition Costs Per Order. Can you give me a better idea?

 
At 1:35 PM, Blogger Charles Dominick, SPSM said...

Acquisition costs per order include all costs associated with the life span of the order: the cost of the buyer's time, the cost of the pre-printed form, the cost of sending the order (by fax or mail), an amortized cost of the purchase order system including costs to implement that system, the cost to receive orders, pay invoices, etc.

 
At 1:40 PM, Anonymous rita said...

I thought that was what you meant. In that case, is there an industry standard for this cost? You can imagine the arguments over what these costs are.

 
At 1:56 PM, Blogger Charles Dominick, SPSM said...

Those arguments are exactly why there isn't an industry standard. But these two links cite separate, independent studies that come up with similar numbers:

http://econ.gsia.cmu.edu/ecommerce/economist_1.htm

http://www.infor.com/infor/Industries_Distribution_eComm_940.htm

 
At 1:57 PM, Blogger Charles Dominick, SPSM said...

Those links seem to be too long. Try these:

http://tinyurl.com/wq6y3

http://tinyurl.com/y7a6gs

 
At 5:40 AM, Anonymous onwuzuam said...

I have just stumbled upon this blogsite.
I have been challenged by a former school classmate to help look up and advise on the state of the Warehouse of his Engineering Company.
I have spent most of my career in Supply Chain handling Procurement, though I have also undertaken an oversight responsibility of a Warehouse. Can I please request that you volunteer ideas and tips on highlights for my audit?
Here's thanking you in advance for your anticipated professional camaraderie and espirit de corps.

 
At 10:51 AM, Anonymous Anonymous said...

Hi my name is Muhammad from Singapore. I would like to thank u Sir as u really save me. I did not have an idea of the equation for EOQ until i came to your website. I am a final year student with University of Northumbria and i am passing my assignment tommorow. Thanks to u i will have more confidence in submitting it.

 
At 10:56 AM, Blogger Charles Dominick, SPSM said...

You're welcome, Muhammad. Thank you for visiting the blog. Good luck with your assignment.

 
At 11:03 PM, Anonymous Anonymous said...

Hi, I am HM from Malaysia. I've been a purchaser for almost 5 yrs and never thought everything has a formula for it!Thanks Charles! Can I ask what is 'Average Lead Time'?

 
At 1:14 PM, Blogger Charles Dominick, SPSM said...

Lead time is the amount of time between the time that an order is placed and the time that the order is delivered. So average lead time is the mean or average amount of time that you observe over a series of orders for that product or service.

 
At 4:49 AM, Anonymous Anonymous said...

Hi,
Thanks for your valuable information. Can u give me some details of Warehouse manangement, like basic requirement for a new warehouse setup ( Standard rules like fire extinuguisher required for 100 sqft etc) if u able to

 
At 12:39 PM, Blogger Charles Dominick, SPSM said...

Thanks for stopping by the blog. A great resource for warehouse management is our podcast entitled "Should Purchasing Manage The Warehouse?" Check it out at our page for the Purchasing & Supply Management Podcast Series.

I hope that this helps.

 
At 12:04 PM, Blogger Ron Loo said...

Hi, I have found some very useful suggestions and information here. However there is one equation that I cannot figure out. The equation is for maximum SSL under the article "How much inventory is too much?"
Maximum SSL = MHDU x (MHLT - ALT)
For me, it does not make sense. I thought that a more reasonable formula would be SSL = MHDU x MHLT.
Pls enlighten me.
Thanks
Ron

 
At 6:07 PM, Blogger Charles Dominick, SPSM said...

Thanks for your comment, Ron.

SSL is a quantity of goods.

To get a quantity on one side of the equation, you must have quantities on the other side of the equation.

While MDHU is a quantity of goods, MHLT is a number of days not a quantity of goods. Multiplying number of days by usage per day (MHDU) gives you a quantity of goods.

Example: 3 days x 4 units per day equals 12 units over the period of days.

I suggest that you plug numbers into the variables and do the calculation a few times to get a good grasp on how the formula works.

Thanks again!

 
At 10:36 PM, Anonymous Anonymous said...

WHAT DA HELL IS ALL THAT??????????
I CAN WRITE A BETTER EQUATION THAN THAT,,,,,
ANKUT FELLOW CHARLES!!!!!!!!!!!

 
At 7:52 AM, Blogger Charles Dominick, SPSM said...

I didn't invent the EOQ formula...it has been around a lot longer than I've been in purchasing.

If your only variables are acquisition costs and holding costs, it is a very valid formula. In my current research, though, I am finding that it doesn't work all that well when there are other constraints. I hope to invent an alternate formula by the end of the year. Then you can feel free to assail me for a formula you don't like!

 
At 2:54 AM, Anonymous Anonymous said...

thank you very much sir, i got lots of useful information from your web and the formula which you have given for inventory and managment is really very useful and use that in our org , and i do apreciate your hard work and facilitating us .

Thanks
Fara sadat from Afghanistan

 
At 7:43 AM, Blogger Charles Dominick, SPSM said...

You're welcome, Fara Sadat! Thanks for visiting.

 
At 12:33 AM, Blogger mary jean said...

I am fresh graduate and currently working to a newly established korean construction company in the Philippines. We don't still have an accounting software to cater the needs of our expanding business because we still in the experimental stage. We spend over Php 500,000 expenses for a month about half came from the operating expense of the office alone. we also don't know how to make an effective inventory management because all we have hired were fresh graduates.
Can you give me any suggestions on how to solve these problems?
Thank you!

 
At 8:15 AM, Blogger Charles Dominick, SPSM said...

Hi Mary Jean,
Electronic accounting is quite essential. We use Quickbooks and it is quite affordable. Microsoft Money, while really geared for home use, can work for a small business if you can't afford Quickbooks. And Excel can even work if you have someone on staff who can set it up properly.

To learn the basics about inventory management, I recommend enrolling in our online class "Mastering Purchasing Fundamentals" (http://www.NextLevelPurchasing.com/fundamentals-purchasing.html) and checking out our list of articles on the topic at http://del.icio.us/supply_chain_articles/inventory

Good luck!

 
At 5:44 AM, Blogger Ankit said...

how does the formula changes, when there is a back - order cost involved.

thanks,
Ankit

 
At 8:01 AM, Anonymous Raed said...

DEAR
i didn't get the real meanning of EQO and how can i useful from this number, is it like reorder point?

please inform me

you really made me interesting

regardS

 
At 8:05 AM, Blogger Charles Dominick, SPSM said...

Thanks for stopping by, Ankit.

I'd be happy to answer your question. First, can you please clarify what a "backorder cost" means to you?

 
At 8:06 AM, Blogger Charles Dominick, SPSM said...

Thanks for stopping by, Raed.

EOQ is not a reorder point. It represents the quantity you should order when your inventory level reaches the reorder point.

I hope this helps...thanks again!

 
At 3:34 AM, Anonymous Anonymous said...

Hello there, I was wondering I am struggling with my team on what would be the best way code components in a raw material stores?

 
At 8:30 PM, Blogger Tog said...

Hi,with big corporations having customized softwares to manage their stock..could you kindly give me some professional advice on a software I can use to manage my stock outside my office domains when I have to work from home and don't have access to the company's software? I have tried microsoft excel but need something more sofisticated.
Thanks.
Tog

 
At 12:26 PM, Blogger Charles Dominick, SPSM said...

Tog,
The answer to your question depends on a number of things like what inventory system your company uses, what transactions you will need to execute, and, if you use an offline system, how it will be integrated.

I recommend checking with your IT staff to explore this further. Perhaps there is a way to access your inventory system remotely through a VPN.

 
At 4:45 AM, Blogger Sanjay said...

u give the definition of critical,non critical and insurance items in inventory classification

 
At 3:42 PM, Blogger Charles Dominick, SPSM said...

Hi Sanjay,
Thank you for posting a comment.

Critical inventory items are those items that would have a severe impact on your company and its ability to continue its operations and serve its customers if such items ran out of stock. For manufacturers, this usually means the custom-made components and assemblies as well as raw materials.

Non-critical inventory items are those items that are either readily available (e.g., from one of many local distributors) and/or would not cause a major problem in the event of a stock out.

With regard to insurance items, you may be referring to what is referred to as safety stock. Please see http://www.nextlevelpurchasing.com/articles/safety-stock-calculation.html for more information on safety stock.

 
At 1:00 AM, Anonymous Anonymous said...

as a professor while teaching I am interested to know how the tire concept of inventory management can be dovetailed to drug selection, procurement , distribution in order to be a little more cost effective on ne hand and maintaining regularity of essential drug supply in health care fecilities

 
At 10:28 AM, Blogger Charles Dominick, SPSM said...

Dear Professor:
Inventory management can be applied fairly uniformly to pretty much any industry, including the pharmaceutical industry.

What must be kept in mind with pharmaceuticals, however, is expiration dates. Your order quantity should not result in drugs becoming expired before they are used.

 
At 10:54 PM, Anonymous bhuvana said...

Hi sir...

Really am thankful for you.

im bhuvana from india doing my final year engineering.

ur blogs and ideas about
"inventory management" helps me a lott in my project work.
Thanks a lott sir....

 
At 9:14 AM, Blogger Charles Dominick, SPSM said...

Thanks for your kind words, Bhuvana! Best of luck in your project work.

 
At 7:35 AM, Anonymous Radhakrishnan said...

Dear Charles,

I am Radhakrishnan from India. I have gone through your blog and found quiet interesting. You have explained Safety stocks and EOQ calculation in simple way even layman can understand. I will go through more contents and any query I will get back to you.

Thanks

 
At 10:43 AM, Blogger Charles Dominick, SPSM said...

Thanks for stopping by, Radhakrishnan.

 
At 9:39 AM, Blogger jimmy said...

Please help me with the following a)Inventory Managment and Costs
b)Cost reduction measures
c)Vendor developments
e)Inventory Logistics

Hi i am jimmy from India

 
At 2:01 PM, Blogger Charles Dominick, SPSM said...

Hi Jimmy,
There are many free articles on several of the topics you mentioned at http://www.NextLevelPurchasing.com/free.html

 
At 12:01 AM, Anonymous Anonymous said...

hi,
how to adjust the beg.balance. if it is already recorded.?

 
At 3:26 AM, Anonymous Anonymous said...

can u post me lit. review of some other authors on the subject of computerised stock control, defination and meaning,importance,basic computerised stock control system and their recommendation and conclusion

 
At 4:15 AM, Anonymous Anonymous said...

Hi . really intresting & quite useful blogs . can you guide how we can get Certification from you .
Thanks &Regards
Ali .
india

 
At 10:38 AM, Blogger Charles Dominick, SPSM said...

Hi Ali,
For complete information on how to earn your certification through Next Level Purchasing, please visit http://www.NextLevelPurchasing.com/spsm.html

or call us at +1-412-294-1990

or email us at help@nextlevelpurchasing.com

We are ready to assist you!

 
At 4:30 PM, Anonymous Anonymous said...

Good Day!

Is there any formula to get the EOQ using MS Excel, it would be very helpful for me if you can give me an example of the formula on how to get the EOQ using MS Excel.

Thank you very much

 
At 9:05 AM, Blogger Charles Dominick, SPSM said...

Our online course "Microsoft Excel For Purchasing Professionals" can teach you how to create formulas for mathematical equations into Excel. While the course does not contain the EOQ equation or the square root function, it does enable you to independently convert equations into Excel format, giving you independence for success in the future.

You can learn more about Microsoft Excel For Purchasing Professionals at http://www.NextLevelPurchasing.com/classesexcel.html

 
At 6:46 AM, Blogger perry said...

Economi order quantity (EOQ)basically considers two type of costs as important costs.
Briefly explain these two costs and make a graphical presentaion of the two costs.

 
At 8:42 AM, Blogger Charles Dominick, SPSM said...

Sorry, Perry.

The wording of your request is similar to the wording we receive from people who want to copy material for an academic project. We decline responding to those types of requests. Our policy can be found at:

http://www.purchasingcourses.com/2007/03/assistance-for-academic-projects.html

 
At 12:21 AM, Blogger Masud said...

Hi I am an Industrial Engineer from Bangladesh currently working in a consultancy firm for developing an effective inventory management software for a renowned furniture industry in my country. but as i just passed out from the university this year, i have no practical expertise on this matter. so can u help me in this regard.....

 
At 4:11 PM, Blogger Charles Dominick, SPSM said...

Hello Masud,
Thank you for stopping by.

I suggest starting at my page on delicious.com that links to all of my inventory-related articles - http://delicious.com/supply_chain_articles/inventory

Good luck!

 
At 10:30 AM, Anonymous Anonymous said...

Hello sir i am abhinav from India.I am a B.E(IT)final year student.As dis is my final year,i have 2 make a project. I have choosen "Inventory Management System using Barcode". This IMS is basically for my college. Sir,can you help me in my project work. i will be very thankfull 2 u.....

 
At 1:27 PM, Blogger Charles Dominick, SPSM said...

While Next Level Purchasing does provide some consulting services, as a student you are unlikely to be willing or able to fund a personal, one-on-one engagement with us. However, I can direct you to a link to some free resources that I've developed on the topic of inventory management:

http://delicious.com/supply_chain_articles/inventory

Good luck!

 
At 7:31 AM, Anonymous Anonymous said...

please kinldy helpme out with the importance ofcomputer in stock inventory

 
At 3:46 AM, Anonymous thomas said...

I am THomas, just to thank you for this wonderful resource. I really learnt a lot. Please continue with the good work.

 
At 1:38 PM, Blogger Charles Dominick, SPSM said...

Thanks for the feedback, Thomas!

 

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