Hello,

I have a spreadsheet where I calculate my potential FI date based on the average monthly growth of my portfolio (appreciation + new deposits).

I was using the dumbest formula: ((yearly spending * 25) - (saved sum / average monthly appreciation in dollars)) / 12 and this would give me how many months I have left. I am completely overlooking compound interest and when I put my numbers into calculator soup, I'm getting a date 4 years earlier (a third earlier!)

I got lost with the huge formulas required and I'm not too hot with logarithms etc. Is there a straight-forward formula I could use to calculate when I'll hit my FI objective given a 7.2% yearly rate, 12 payments per year, interest compounding 12 times a year end of period, current monthly payments and the already saved sum?

Thanks,