Compound Interest Calculator
See how savings or investments grow with compound interest and optional monthly contributions.
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How to Use
- 1
Enter the starting amount and the annual interest rate.
- 2
Choose the compounding frequency — yearly, monthly or daily.
- 3
Add an optional monthly contribution to see regular saving.
- 4
The final balance, total contributions and interest earned update instantly, followed by a year-by-year table.
Examples
10,000 at 7% for 10 years
Input
Initial 10,000 · rate 7% · 10 years · monthly compoundingOutput
Final balance ≈ 20,096, interest ≈ 10,096Adding 200 every month
Input
Initial 10,000 · rate 7% · 10 years · +200 monthlyOutput
Final balance ≈ 54,710, contributed ≈ 34,000FAQ
How is the annual rate applied?
The nominal annual rate is divided by the number of compounding periods per year. The result is converted to an equivalent monthly growth factor so contributions can be added month by month.
When are monthly contributions added?
At the end of each month, after that month’s growth has been applied. The first contribution therefore does not earn interest in month one.
Is inflation or tax taken into account?
No. The projection is nominal — use a lower rate if you want to approximate the effect of tax or inflation.