Compound interest calculator
Projection with contributions, formula and yearly table.
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Balance after 10 years
31,998.32
- Total contributed
- 22,000.00
- Interest earned
- 9,998.32
- Multiplier
- × 1.45
Without contributions: A = P × (1 + r/n)^(n·t). Contributions are added at the end of each month.
| Year | Total contributed | Interest earned | Balance |
|---|---|---|---|
| 1 | 11,200.00 | 539.50 | 11,739.50 |
| 2 | 12,400.00 | 1,168.01 | 13,568.01 |
| 3 | 13,600.00 | 1,890.06 | 15,490.06 |
| 4 | 14,800.00 | 2,710.44 | 17,510.44 |
| 5 | 16,000.00 | 3,634.20 | 19,634.20 |
| 6 | 17,200.00 | 4,666.60 | 21,866.60 |
| 7 | 18,400.00 | 5,813.23 | 24,213.23 |
| 8 | 19,600.00 | 7,079.91 | 26,679.91 |
| 9 | 20,800.00 | 8,472.79 | 29,272.79 |
| 10 | 22,000.00 | 9,998.32 | 31,998.32 |
Theoretical projection with a constant rate, excluding tax, fees and inflation. Past returns don't guarantee future ones.
What it does: Compound interest calculator
Compound interest means interest earns interest of its own. This calculator projects how a balance grows at a constant rate with regular contributions, and shows the growth year by year.
It helps you understand the effect of time and regular saving; it is not a forecast for any specific product.
How to use it
- Enter the initial amount and, optionally, a monthly contribution.
- Enter the annual interest rate and the number of years.
- Choose how often interest is compounded.
- Check the final balance, the interest earned and the yearly table.
Examples
Steady saving
10,000 up front plus 100 a month at 5 % for 10 years, compounded monthly: about 32,000, of which almost 10,000 is interest.
The power of time
With the same figures over 30 years, the interest earned exceeds everything you put in.
Limits, formulas and assumptions
- A = P × (1 + r/n)^(n·t), where r is the annual rate, n the compounding periods per year and t the years.
- Contributions are added at the end of each month and start earning interest the following month.
- Tax, fees and inflation are not deducted, and they all reduce the real return.
Frequently asked questions
What's the difference between simple and compound interest?
Simple interest is always calculated on the original amount; compound interest is added to the balance and earns more interest.
Does compounding frequency matter?
A little: more frequent compounding earns slightly more, but the difference between monthly and daily is small.
What is APY/AER?
The annual equivalent rate, a single yearly percentage that includes the effect of compounding.
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