Compound Interest Calculator
See how much your money can grow when interest compounds and you keep adding to it every month.
Future value$196,665
- Total contributed
- $82,000
- Interest earned
- $114,665
- Growth multiple
- 2.40×
Growth over time
Starting with $10,000 and adding $300 a month at 7% a year:
| Years | Future value | Interest earned |
|---|---|---|
| 5 years | $35,654 | $7,654 |
| 10 years | $72,022 | $26,022 |
| 15 years | $123,578 | $59,578 |
| 20 years | $196,665 | $114,665 |
| 30 years | $447,156 | $329,156 |
| 40 years | $950,558 | $796,558 |
How it works
The annual rate is converted to an equivalent monthly rate based on how often interest compounds.
Each month the balance earns interest, then your contribution is added at the end of the month.
Tips
- Starting early matters more than starting big. Time does most of the work.
- Fees count. A 1% yearly fee can eat a large share of your growth over decades.
Frequently asked questions
What is compound interest?
Interest earned on both your original money and the interest it has already earned. Over long periods it can be larger than everything you put in.
What's the Rule of 72?
A shortcut: divide 72 by the annual rate to estimate how many years it takes money to double. At 8%, about 9 years.
Results are estimates for planning only and are not financial advice.