How Long to Double Money at 12%
At 12% a year, money doubles in 6.1 years. The Rule of 72 says 6.0.
Doubles in
6.1 years
Quadruples in
12.2 years
Grows 8 times in
18.3 years
Rule of 72 estimate
6.0 years
What different amounts become
| Start | After 6.1 years | After 12.2 years | After 18.3 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 12%
| Years | $1,000 becomes | $10,000 becomes | Growth |
|---|---|---|---|
| 5 | $1,762 | $17,623 | 1.76x |
| 10 | $3,106 | $31,058 | 3.11x |
| 15 | $5,474 | $54,736 | 5.47x |
| 20 | $9,646 | $96,463 | 9.65x |
| 25 | $17,000 | $170,001 | 17.00x |
| 30 | $29,960 | $299,599 | 29.96x |
| 40 | $93,051 | $930,510 | 93.05x |
| 50 | $289,002 | $2,890,022 | 289.00x |
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 12% the shortcut is off by 0.1 years.