How long until your money doubles?

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)


n = number of years
b = interest (3% = .03)

and if you want to count for inflation

n = ln(2) / ln(1+b-f)


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.