How Long to Double Money at 15%
At 15% a year, money doubles in 5.0 years. The Rule of 72 says 4.8.
Doubles in
5.0 years
Quadruples in
9.9 years
Grows 8 times in
14.9 years
Rule of 72 estimate
4.8 years
What different amounts become
| Start | After 5.0 years | After 9.9 years | After 14.9 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 15%
| Years | $1,000 becomes | $10,000 becomes | Growth |
|---|---|---|---|
| 5 | $2,011 | $20,114 | 2.01x |
| 10 | $4,046 | $40,456 | 4.05x |
| 15 | $8,137 | $81,371 | 8.14x |
| 20 | $16,367 | $163,665 | 16.37x |
| 25 | $32,919 | $329,190 | 32.92x |
| 30 | $66,212 | $662,118 | 66.21x |
| 40 | $267,864 | $2,678,635 | 267.86x |
| 50 | $1,083,657 | $10,836,574 | 1,083.66x |
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 15% the shortcut is off by 0.2 years.