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Centre of gravity for warehouse location – try the working model

June 8th, 2011 | By: Martin Arrand

I’ve just posted up a development version of a centre of gravity model for distribution centre location. It uses Google Maps, and it is really easy to use, and completely free. Try it here now.

I regard it as a “toy” application, but I’m surprised how usable it is (down to the familiar Google interface I think rather than my design skills). And it really does work.

I am going to use it to demonstrate the principle of COG in logistics networks, as a teaching and communication aid rather than a serious analysis tool. But maybe the next time the team is debating where to go for a night out we can plot all our home locations and see where the most convenient spot is.

It is an early release so quite buggy and breakable, and all feedback is welcome – just drop me a comment.

That link again: Centre of Gravity Model.


Comment from Nikolaj
Time 18 January 2013 at 8:45 am

Hi, I am very impressed by the Center of Gravity tool, it is very usefull.
However, is it possible to build a link so that one can upload a list of addresses, which then are plotted on the map. These plots could then be multiple and very precise, so that the “center of gravity” will be calculated from the data uploaded?
Example: http://www.batchgeo.com , you upload data, but have no “gravity calculater”.. the mix of this function and your calculator would be the perfect tool!!
Looking forward to hear if this is possible.

Comment from Collette Blake
Time 4 June 2013 at 8:35 am

Hi Martin,
Firstly thanks for your work on the centre of gravity tool. You mentioned in the accompanying notes that you might be able to add an editable table. Do you think this might still be on the cards? Also, is there/or would there be any facility to include the point of origin of the goods? This would ‘drag’ the optimum location for a warehousing site.
Kind regards
Collette Blake

Comment from Martin Arrand
Time 28 June 2013 at 3:26 pm

Hi Nikolaj,

Thanks for the kind and encouraging comments. When I built the tool (a while back now) I remember there were certain restrictions to geocoding using the Google Maps API. Having looked recently, I can see it would be possible to do something like you suggest. The question is really whether I have time to fit this in among my other (paid) work – as you can see the blog has been rather neglected lately.
However, in principle it all looks possible, and I may make some upgrades to the CoG model this year as a warm-up to constructing a “proper” network optimizer (i.e. multiple warehouses, total cost minimization, capacity constraints)

Best regards,

Comment from Martin Arrand
Time 28 June 2013 at 3:32 pm

Hi Collette,

Yes, I may still do that, time permitting. See also my comment to Nikolaj about geocoding (which would mean being able to give a list of postcodes, for example).

Point of supply is also a good idea. If you wanted to do that with the current model, you could add one location and make the weight on it the sum of the rest of the (customer) weights (or a factor thereof, reflecting the fact that bulk inbound freight is usually less costly than customer deliveries). I know that’s a little messy, but it would make your model more realistic.

Best of luck,

Comment from Cheng
Time 11 July 2013 at 4:16 am

Hi Martin,

This is so cool a model. I think it’s a basic combination of Infor and Arcview or other similar softwares. Keep upgrading it!

BTW, is it possible I connect you on Linkedin? It will be easier for me to keep watching if you have any other gorgeous ideas/tools.

Comment from Martin Arrand
Time 11 July 2013 at 6:10 pm

Thanks for the kind comments. I have sent you a connection request on LinkedIn.

Comment from Robert
Time 22 August 2014 at 4:12 pm

Dear Martin

I am very impressed with your
Centre of gravity Model. I have a question and hope you can help

By using your model, if center of gravity is located in the middle of the ocean or lake, how do you prevent or fixed? Since the location in in the middle of the ocean or lake is not practical?

Please email me? Thank you for your help.

Comment from Martin Arrand
Time 4 November 2014 at 6:00 pm

Hi Robert.

Thanks for your question. CoG is always going to be a pretty basic way of looking at a network. In real life, when siting a single hub we have to look at the practicalities of the result of the analysis. For example, we should consider the transport infrastructure (road network) and existing facilities (logistics parks, etc), local costs (labour cost and availability, facility rents, taxes). Any or all of these might lead us to place a hub somewhere away from the dead centre of gravity. As indeed would the existence of a lake or other natural feature.

If you find a CoG in the middle of an ocean, then I would suggest you actually have 2 or more groups of customers on either side of the ocean, and you would be better off looking at the CoG of each group separately.

Hope that helps, and sorry I’ve not replied earlier.