How Long to Double Money at 2%
At 2% a year, money doubles in 35.0 years. The Rule of 72 says 36.0.
Doubles in
35.0 years
Quadruples in
70.0 years
Grows 8 times in
105.0 years
Rule of 72 estimate
36.0 years
What different amounts become
| Start | After 35.0 years | After 70.0 years | After 105.0 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 2%
| Years | $1,000 becomes | $10,000 becomes | Growth |
|---|---|---|---|
| 5 | $1,104 | $11,041 | 1.10x |
| 10 | $1,219 | $12,190 | 1.22x |
| 15 | $1,346 | $13,459 | 1.35x |
| 20 | $1,486 | $14,859 | 1.49x |
| 25 | $1,641 | $16,406 | 1.64x |
| 30 | $1,811 | $18,114 | 1.81x |
| 40 | $2,208 | $22,080 | 2.21x |
| 50 | $2,692 | $26,916 | 2.69x |
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 2% the shortcut is off by 1.0 years.