How Long to Double Money at 10%
At 10% a year, money doubles in 7.3 years. The Rule of 72 says 7.2.
Doubles in
7.3 years
Quadruples in
14.5 years
Grows 8 times in
21.8 years
Rule of 72 estimate
7.2 years
What different amounts become
| Start | After 7.3 years | After 14.5 years | After 21.8 years |
|---|---|---|---|
| $1,000 | $2,000 | $4,000 | $8,000 |
| $5,000 | $10,000 | $20,000 | $40,000 |
| $10,000 | $20,000 | $40,000 | $80,000 |
| $25,000 | $50,000 | $100,000 | $200,000 |
| $50,000 | $100,000 | $200,000 | $400,000 |
| $100,000 | $200,000 | $400,000 | $800,000 |
Growth over time at 10%
| Years | $1,000 becomes | $10,000 becomes | Growth |
|---|---|---|---|
| 5 | $1,611 | $16,105 | 1.61x |
| 10 | $2,594 | $25,937 | 2.59x |
| 15 | $4,177 | $41,772 | 4.18x |
| 20 | $6,727 | $67,275 | 6.73x |
| 25 | $10,835 | $108,347 | 10.83x |
| 30 | $17,449 | $174,494 | 17.45x |
| 40 | $45,259 | $452,593 | 45.26x |
| 50 | $117,391 | $1,173,909 | 117.39x |
How it is worked out
Years to double = ln(2) / ln(1 + r)
ln = natural logarithm, r = rate as a decimal.
The Rule of 72 is the shortcut version. Divide 72 by the rate.
At 10% the shortcut is off by 0.1 years.