72法則
計算投資翻倍所需的時間。
輸入
翻倍年數
投資翻倍年份 2036
用72除以年化收益率，即可估算投資翻倍所需的年數。反過來，用72除以目標年數，可求出所需的年化收益率。
翻倍增長時間線
@ 7% 年化收益率
資產對比
通貨膨脹影響
72法則同樣揭示了通脹侵蝕購買力的速度。年通脹率3%時，物價在短短24年內就會翻倍。
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精心挑選的實用工具
Using the Rule of 72 to Estimate Doubling Time
Overview
The Rule of 72 is a quick mental shortcut for how long it takes an investment to double at a fixed annual return: just divide 72 by the rate. It is remarkably accurate for typical rates and great for sanity-checking growth without a spreadsheet. This calculator applies it instantly, and also works in reverse to find the rate needed to double in a given time.
How to Use (Step by Step)
- 1
Enter the annual rate
The expected yearly return or interest rate as a percentage.
- 2
Read the doubling time
The tool divides 72 by the rate to estimate years to double.
- 3
Or solve for the rate
Enter a target number of years to see what annual rate doubles your money in that time.
How It Works
Years to double ≈ 72 ÷ annual interest rate (as a percent). At 8%, money doubles in about 9 years; at 6%, about 12 years. The 72 works because it closely approximates the exact logarithmic doubling formula for rates between roughly 4% and 15%. To find the required rate instead, divide 72 by the number of years you have.
When to Use This
Quickly estimating how fast savings will grow. Comparing the long-term impact of different return rates. Showing how inflation erodes purchasing power (how fast prices double).
Frequently Asked Questions
Very close for rates between about 4% and 15%. At higher or lower rates the approximation drifts slightly from the exact figure, but it remains a useful estimate.