I wrote about calculating appreciation so now you can figure out how much your money is worth in n number of years, but what if you want to know how long your money will take to double? Since I don’t know how to embed an online calculator here, you are going to need a spreadsheet (use this one) or calculator unless you can do log’s in your head.
n = ln(2) / ln(1+b)
where
n = number of years
b = interest (3% = .03)
and if you want to count for inflation
n = ln(2) / ln(1+b-f)
where
f = inflation (3% = .03)
Dad always said your money would double every 7 years. Turns out he was figuring on 10% interest or appreciation. At 7% your money will double every 10 years. Add 3% inflation and it’ll double every 18 years.
Here’s a very simple Excel spreadsheet to run the calculations for you.