The Rule of 72 Do you know how long it may take for your investments to double in value? The Rule of 72 is a quick way to figure it out. Share | Related Content What Can a Million Dollars Buy You? $1 million in a diversified portfolio could help finance part of your retirement. The Sequence of Returns A look at how variable rates of return impact investors over time. Taxable vs. Tax-Deferred Savings Use this calculator to compare the future value of investments with different tax consequences.