The Rule of 72 is a guide to determining how quickly an investment will double based on the interest rate.  Divide 72 by the interest rate to approximate the number of years it will take for an amount to double.

Use the calculator below to calculate the doubling time for an interest rate (APY).  Include a tax rate if the investment will be reduced by an annual tax on the increase.


Subscribers may use this tool.
Create an Account or Sign In
Examples
Years to Double:
Rate % Years
0.25288.0
0.50144.0
0.7596.0
1.0072.0
1.2557.6
1.5048.0
1.7541.1
2.0036.0
2.2532.0
2.5028.8
2.7526.2
3.0024.0
3.2522.2
3.5020.6
3.7519.2
4.0018.0
4.2516.9
4.5016.0
4.7515.2
5.0014.4
5.2513.7
5.5013.1
5.7512.5
6.0012.0
6.2511.5
6.5011.1
6.7510.7
7.0010.3
7.259.9
7.509.6
7.759.3
8.009.0
8.258.7
8.508.5
8.758.2
9.008.0
9.257.8
9.507.6
9.757.4
10.007.2
10.257.0
10.506.9
10.756.7
11.006.5
11.256.4
11.506.3
11.756.1
12.006.0
12.255.9
12.505.8
12.755.6
13.005.5
13.255.4
13.505.3
13.755.2
14.005.1
14.255.1
14.505.0
14.754.9
15.004.8
15.254.7
15.504.6
15.754.6
16.004.5
16.254.4
16.504.4
16.754.3
17.004.2
17.254.2
17.504.1
17.754.1
18.004.0
18.253.9
18.503.9
18.753.8
19.003.8
19.253.7
19.503.7
19.753.6
20.003.6
Google Analytics Alternative