Worked example
Invest $10,000 once and leave it for 20 years at an assumed 7% a year. It grows to an estimated $38,697, of which $28,697 is assumed growth.
- Amount invested
- $10,000
- Assumed return (per year)
- 7%
- Time period
- 20 years
- Estimated returns
- $28,697
- Estimated value
- $38,697
| Year | Estimated returns | Estimated value |
|---|---|---|
| 1 | $700 | $10,700 |
| 2 | $1,449 | $11,449 |
| 3 | $2,250 | $12,250 |
| 4 | $3,108 | $13,108 |
| 5 | $4,026 | $14,026 |
| 10 | $9,672 | $19,672 |
| 15 | $17,590 | $27,590 |
| 20 | $28,697 | $38,697 |
How to use this calculator
- Enter the amount you’re investing today.
- Enter the annual return you expect — and test a conservative one.
- Choose how many years you’ll leave it invested.
Compounded annually: $10,000 at 7% for 20 years grows to $38,697.
Frequently asked questions
How long does it take to double my money?
At 7% a year, about 10.2 years. The “rule of 72” gives a quick estimate: divide 72 by the annual return (72 ÷ 7 ≈ 10.3).
What if returns come in lower?
Small differences compound. At 4% instead of 7%, $10,000 grows to $21,911 over 20 years instead of $38,697.
Is a lump sum better than investing monthly?
Investing everything now gives the whole amount more time to grow, but it also exposes all of it to a market drop right away. Spreading it out over months lowers that risk at the cost of some time in the market. Use the Investment Calculator to model a monthly plan.
Are taxes and fees included?
No. The projection is before taxes, fund expenses and inflation. Use a lower return if you want a rough after-cost figure.