How long will it take to double my savings?

Compound interest can have a dramatic effect on the growth of a single deposit. By dividing 72 by your investment return you can determine the amount of time required for your money to be worth about twice as much as it is today.

Future value of savings

Initial balance or deposit ?

The amount you're starting with, or plan to deposit, before it starts growing.

Before-tax return on savings ?

The annual growth rate your savings earn before taxes are taken out.

Table of Historic Rates of Return. Inflation 2.9%, U.S. Treasury Bills 3.3%, Long-term Government Bonds 5.0%, U.S. Large-Company Stocks 10.4%, and U.S. Small-Company Stocks 11.8%. Past performance is no guarantee of future results. Source: Ibbotson SBBI 1926-2024

Marginal tax bracket ?

The tax rate applied to the interest your savings earn each year.

Table of Federal Income Brackets and Rates. Tax Rate For Single Filers For Married Individuals Filing Joint Returns For Heads of Households 10% $0 to $11,925 $0 to $23,850 $0 to $17,000 12% $11,925 to $48,475 $23,850 to $96,950 $17,000 to $64,850 22% $48,475 to $103,350 $96,950 to $206,700 $64,850 to $103,350 24% $103,350 to $197,300 $206,700 to $394,600 $103,350 to $197,300 32% $197,300 to $250,525 $394,600 to $501,050 $197,300 to $250,500 35% $250,525 to $626,350 $501,050 to $751,600 $250,500 to $626,350 37% $626,350 or more $751,600 or more $626,350 or more.

Enter your values and select Calculate.

The years-to-double figure tells you how long it takes your money to grow to twice its starting size, after the taxes you specified come out of the interest earned each year. It does not include any withdrawals, fees, or additional deposits along the way — it's a pure growth-on-growth number, so treat it as a rough planning marker rather than a guarantee of what your account will actually show on that date.

Two inputs drive this result far more than the third: the before-tax return and the tax bracket. A return that looks modest before tax can shrink noticeably once your marginal rate is applied to the interest, which is why the after-tax path to doubling often takes longer than the classic 'rule of 72' shortcut suggests. The initial balance changes the dollar figure at the finish line but not how many years it takes to get there — doubling is doubling, whether you start with a little or a lot.

What's left out matters too: inflation isn't factored in, so a doubled balance won't buy twice as much if prices have risen in the meantime. Real investment returns also don't arrive as a smooth, constant rate — they fluctuate year to year — and this calculator assumes a steady one throughout.

It's worth rerunning this whenever your tax bracket changes, when you're comparing where to hold savings (a taxable account versus something tax-advantaged), or simply once a year as a check-in. Having a concrete number, even an approximate one, is a useful habit — and small improvements in return or tax efficiency compound into a meaningfully shorter wait.

This information may help you analyze your financial needs. It is based on information and assumptions provided by you regarding your goals, expectations and financial situation. The calculations do not infer that the company assumes any fiduciary duties. The calculations provided should not be construed as financial, legal or tax advice. In addition, such information should not be relied upon as the only source of information. This information is supplied from sources we believe to be reliable but we cannot guarantee its accuracy. Hypothetical illustrations may provide historical or current performance information. Past performance does not guarantee nor indicate future results.