Compound Interest Calculator
Enter a starting amount, regular contributions and an assumed annual growth rate to see a year-by-year mathematical projection. This is a projection based on the rate you enter — not a prediction of future returns.
Your assumption — not a predicted return. 0% is fine.
Projected value after 10 years under the assumptions above. This is a mathematical projection, not a prediction of future returns.
| Year | Contributions | Growth | Balance |
|---|---|---|---|
| 1 | $3,600 | $736 | $14,336 |
| 2 | $3,600 | $1,003 | $18,939 |
| 3 | $3,600 | $1,287 | $23,827 |
| 4 | $3,600 | $1,589 | $29,015 |
| 5 | $3,600 | $1,909 | $34,524 |
| 6 | $3,600 | $2,249 | $40,373 |
| 7 | $3,600 | $2,609 | $46,582 |
| 8 | $3,600 | $2,992 | $53,174 |
| 9 | $3,600 | $3,399 | $60,173 |
| 10 | $3,600 | $3,831 | $67,604 |
How this is calculated
We simulate month by month: your chosen compounding frequency is converted to an equivalent monthly rate, your contribution (converted to a monthly-equivalent amount) is added each month, then growth is applied.
The assumed annual rate is entirely your choice. Using 0% simply shows the running total of your contributions with no growth applied.
Formula
Monthly rate = (1 + annual rate ÷ n)^(n ÷ 12) − 1, where n is your chosen compounding periods per yearEach month: balance = (balance + monthly contribution) × (1 + monthly rate)Worked example
A $10,000 starting balance with $300/month contributions at an assumed 6% annual rate compounded monthly grows well beyond the sum of contributions alone over 10 years — the exact figures depend on the numbers you enter.
This calculator provides an estimate based on the numbers and assumptions you enter. It’s for general informational purposes and does not constitute financial, tax, legal, investment or credit advice. See our disclaimer and how we calculate pages for more detail.
Frequently asked questions
No. It's an assumption you choose for this calculation, not a prediction or guarantee of future returns.