This post is part of spreadcheats series.
Today we will learn a fascinating little feature in excel called “goal seek”.
But what good is a feature if we cant find a use for it? So we will build a simple retirement calculator using excel.
Before plunging in to the complex retirement calculations, let us spend a bunch of words understanding what this goal seek is all about.
What is goal seek in excel?
We can think of goal seek as opposite of formulas. Formulas tell you what is the output of a bunch of variables used in an equation (for eg. sumproduct is an equation involving + and *). Goal seek tells you what inputs you need to give in order to get certain output.
For example, you can use goal seek to solve a linear equation or find the internal return rate (IRR) of an investment.
Now that you understand goal seek, let us plan your retirement. 🙂
Make a financial model to estimate your monthly savings to meet retirement goals.
(Note: the image shows commas according to Indian currency formatting.)
In order to proceed, we would need some data, like,
(1) What is your current age?
(2) What is your expected retirement age?
(3) How much do you think you will spend every month when you retire (of course in today’s prices)
(4) Your expectation of inflation (%)?
(5) Your expected return (%) on investments?
Once the data is available, we will need to calculate the following,
I have shown the worksheet on the right with some dummy data.
(6) The yearly expenses at the time of retirement: (3) * (1+(4))^((2)-(1))*12
(7) Corpus required to generate the above amount every year (and leave the principle behind): (6)/(5)
(If these calculations are overwhelming, download the excel retirement calculator workbook here.)
We know how much corpus is needed.
We can use FV() formula to determine the future value of a series of payments made periodically and compounded at a given interest rate.
We know how much the FV() out come should be, but we don’t know how much the input (monthly investment) should be.
This is where goal seek is going to help us.
Let us assume the monthly investment amount will be in cell A5. Let us also assume, the interest rate is in cell A4, retirement age is in A3, current age is in A2.
We will write the FV formula in cell A6 like this = -FV(A4/12,(A3-A2)*12,A5)
(we have to negate FV since it uses weird accounting notations)
Since the cell A5 is blank, the FV will show the value as 0.
Now, we will use goal seek to find out how much cell A5 should have so that A6 will be calculated to the corpus amount required.
Go to Data tab and click on What if analysis and select goal seek. (In excel 2003, it should be in tools menu)
See this screen cast to understand how the goal seek works:
The goal seek window has 3 inputs. The cell you need to change. The cell you want to set and the value to set.
Once you use the goal seek it will find the correct (or closest) value to meet the goal and displays it. If you press OK, the value will be placed in the cell (in our case, in A5)
That is all.
Download the Retirement Calculator Excel Worksheet and play with it
Click here to download the retirement calculator worksheet. Follow the instructions in the workbook to see this example for yourself. Change values to find the amount that you need to save.
Do you find goal seek feature useful?
What do you do with excel goal seek? Do you use it in your modeling, planning worksheets? Tell me your experiences and ideas using comments.
Additional resources:
- Read remaining posts in Spreadcheats series: Become a spreadsheet guru by learning these nifty hacks.
- Excel financial formulas – Help on NPV, FV, PV and more
- Understand why you should start early when it comes to retirement savings
- Buy or rent calculator in Excel – calculate returns on property investments
PS: the retirement calculation steps are derived from this excellent article on smart investor
7 Responses to “Project Dashboard + Tweetboard = pure awesomeness!!!”
I would like to see actual hash-tagged DM tweets go out to the specific information consumers. That would be an interesting way to communicate the key daily data to interested parties.
A Twitter-like secure application like Yammer might be a good fit with this.
For example, how about daily tweets to selected user groups (secure) that would display sales, bookings, cash receipts, cash disbursed and a second version that would show the same info for MTD, QTD or YTD figures.
@Dan, it would be great. I did not taught about implementing it on this dashboard because twitter is blocked to the whole intranet here. However, there's a discussion here about how can we send these tweets to blackberries (probably through e-mail) automatically. (I'd like to see this implemented on a jabber restricted network as well, but here it'll probably not happen)
The wrap-up versions you mentioned doesn't apply to my particular scenario, but on a sales tweetboard it would be a great tool indeed - choosing who will receive which message according to hashtags. I'll think on something, thanks for the advice. 🙂
(Ah, btw, I'm Fernando... 🙂 )
@Dan: That is a fun idea. Instead of tightly integrating twitter functionality with a dashboard, i think it would be cool if we have a "tweet this" button that users can click after selecting a range of cells. We can easily show a dialog with the concatenated output of the selected cells and ask user to edit the text and eventually "send to twitter".
For eg. you can select the annual sales figure cell and click on "tweet this" button upon which a dialog will show the value. Then you can pre-pend it something like "DM @boss look at our sales this year: "
@Aires.. thanks once again.
Wow it looks really good. Not sure though how much the tweet facility would help in real world project management, but certainly having a dashboard on a project should be a key deliverable when learning how to manage a project
The other use of this is during the software development life cycle especially when you have parallel streams of development and testing going on. Using a dashboard is a quick way for everyone on the team to see where the project is at and how it all fits together.
Regards
Susan de Sousa
Site Editor http://www.my-project-management-expert.com
Hi Chandoo,
I purchased the project management toolkit but the dashboard shown above with the imbedded scroll bars. Is it included in the project pack??
Thanks
Sue
The gantt chart section of this dashboard is similar to one I have recently created: http://xlcalibre.com/hr-dashboard-gantt-chart-traffic-light-reportIt has a similar approach with scroll bars, but has a couple of additional features. I've tried to incorporate a traffic light report element, and also allow the timescale to adjusted so that can view it by days, weeks or months.I really like the other tables that you've incorporated, I may well try to replicate them to improve my version!
I am a monitoring and evaluation consultant in international development, and one of the services I offer is to help non-profits and foundations develop performance dashboards. I often advise them to develop dashboards for ongoing programs, rather than for one-time or pilot projects, because of the time involved. I am trying to find out from a few people how long it takes you to develop a project management dashboard, and to what extent the indicators vary from one project to the next.