Rule of 144 Calculator

The Rule of 144 is a quick mental math shortcut to estimate how long it takes for an investment to grow to four times its original value under compound interest. Divide 144 by the annual interest rate (as a percentage) to get the approximate number of years to quadruple. For example, at 6% per year: 144 / 6 = 24 years to quadruple.

The Rule of 144 extends the Rule of 72 (doubling) and Rule of 114 (tripling) to quadrupling. Because quadrupling equals two successive doublings, the time to quadruple is approximately twice the doubling time: 2 x 72 = 144. This is why the constant is 144. The exact constant for quadrupling at common rates is slightly different, but 144 is a close enough approximation for financial planning.

The Rule of 144 is reasonably accurate for rates between 5% and 12%. The exact quadrupling time formula is: years = ln(4) / ln(1 + r) = 2 x ln(2) / ln(1 + r). At 6%, exact is 23.79 years; Rule of 144 gives 24 years (error 0.9%). At 10%, exact is 14.55 years; rule gives 14.4 years (error 1%). The approximation is sufficient for rough planning.

Rule of 72 gives doubling time; Rule of 144 gives quadrupling time. Quadrupling always takes approximately twice as long as doubling at the same rate (because 4 = 2 x 2). So Rule of 144 is just 2 x Rule of 72. At 7%: Rule of 72 gives 10.3 years to double; Rule of 144 gives 20.6 years to quadruple. You can use either rule and multiply by 2 for the other.

Yes. If you start investing $100,000 at age 30 at 7% per year, the Rule of 144 tells you your money will grow to approximately $400,000 (4x) by age 50 (144/7 = 20.6 years). By age 60 it would have doubled once more (another 10 years approximately), reaching about $800,000. This type of rough mental math helps you build intuition for compound growth without needing a detailed financial model.