https://www.thebalancemoney.com/what-is-the-rule-of-72-how-can-it-help-you-double-your-money-453756 - If your annual return is 1%, it takes 72 years to double your money - For a rough estimate on how long it would take, divide 72 by your annualized return rate - For ex), 72 / 5 (5% return rate) = 14ish -