How to determine "interest rate" to make two cells be equal

3rd EDIT: SEE POST 6 BELOW FOR SHEET.

2ND EDIT: Ok, I got somewhat of an answer by learning how to use Goal Seek. Not sure this will suffice because, using Goal Seek, I guess you have to run it manually each time to use it. If there is a "formula" for J2 so that it will be dynamic -- changing as the spreadsheet's other parameters change -- please advise. Thanks.

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I have a sheet such that...

Col I is a column where as you go down by a cell (1 year's time), each year, the balance grows by earning interest (such as you could earn with CD's, bonds or stock market dividends or growth). The interest rate applied is in cell J2.

The bottom cell in Col I, the series of balances by year, is I26.

Col AA is a column that takes the first year's balance and then applies an inflation factor, say, 3%... 3% inflation per year. As you go down Col AA, each year, the balance grows by that inflation -- 3% in this instance. The last cell in the column is AA26.

I am hoping for a formula for J2. I want to determine the interest rate (which, as I said, is in cell J2) necessary such that I26 is equal to AA26. Thus, I would be solving for "what is the interest rate I need to earn each year so that my portfolio keeps up with an inflation of 3%?" Cell J2 will equate to the interest rate necessary to make I26 and AA26 equal.

It's a bit more complicated than that (there are other factors); I have simplified it to ask this question. If I get an answer, I think I can make it work.

Is this a pretty simple formula or do I have to use a Solver. I do not have much experience with Solver and really don't know how to use it. Obviously, not too great on formulas either, lol. Thanks.

(Excel 2010)

EDIT: Hmmm... found something on Goal Seek; will have to read up on this.

Can you post a sample of what you have and what you are trying to get?

I am no expert on these financial functions, but what you describe sounds like what I see them call "future value problem". To understand the financial theory behind it, I would suggest that you put "future value problems" into your favorite search engine.

Excel contains several financial functions that apply to future value type problems (list of available functions) https://support.office.com/en-us/art...n-US&ad=US#bm6 ). I expect that the funciton you want will be the IRR() function, once you understand how it should be used.

I don't think this is a "what type of financial function should I use" question. It really is just a question of "can I input a formula in a cell (J2) such that it will return a number that will change (it will be a percentage -- "interest"), the formula's "rule" being that the value of I26 and AA26 must be equal." (J2 being used as part of the formula used in Col I to apply interest rate growth.)

P.S. I mentioned there is something else in the sheet that is growing the balance other than interest. Otherwise, the answer to the question would be "same as inflation." (If inflation is 3% and interest is 3%, those two bottom lines in those columns will be essentially equal. Not taking into account tax considerations or other factors, just pure arithmetic.)

I'm not bright enough to figure this out, lol, but perhaps a formula may not work because I might have a kind of endless loop in there? The Goal Seeker does work but I have to do it manually.

Here is a sheet to view. I don't know if I have used the proper jargon; hopefully, you can follow it.

Assume you are a real estate investor.
You sell out and get $3,000,000, equating to after tax of $2,400,000.
Assume inflation of 3%.
Your starting draw is $10,000/mo to live on; it grows with inflation.
You will need to earn a return to keep pace with inflation.
Your portfolio balance in 25 years (start=$2.4mm) will need to equal whatever is in AA26 (start bal subject to inflation).
You take a % of your balance each year and buy property (acreage), flipping it for profit; profit goes into the 'portfolio' balance.
Overall balance is invested into CDs, bonds, stocks, something... that earns a return/interest.

Your portfolio balance 25 years from now is shown in I26. You are curious what "interest/return/growth" rate (J2) you would need to earn
on your portfolio balance such that in 25 years, you have kept pace with inflation. (You'd end up with $2.44mm in 25 years in
today's dollars.)

You can use Goal Seeker (see note in sheet) to determine this 'rate.' See sheet for answer of approximately 4.1%.

Would prefer to have a formula for J2 instead of having to use Goal Seeker. A formula would allow you to see J2 changing dynamically
as you change other parameters in the sheet. For instance, you could change inflation rate or change the amount you use to flip
real estate each year. (Is a formula possible or will it be an endless loop or other flaw?)''

Excel 2010