Finance calculator
Compound Interest Calculator
Project investment growth with flexible compounding and monthly contributions.
Your inputs
Adjust the numbers
Contributions are added at the end of each month. Rates are assumed to stay constant.
Projected value
$47,527
Year-by-year projection
| Time | Principal paid | Interest | Balance |
|---|---|---|---|
| 1 year | $12,400 | $567 | $12,967 |
| 2 years | $14,800 | $1,287 | $16,087 |
| 3 years | $17,200 | $2,165 | $19,365 |
| 4 years | $19,600 | $3,212 | $22,812 |
| 5 years | $22,000 | $4,435 | $26,435 |
| 6 years | $24,400 | $5,843 | $30,243 |
| 7 years | $26,800 | $7,446 | $34,246 |
| 8 years | $29,200 | $9,254 | $38,454 |
| 9 years | $31,600 | $11,277 | $42,877 |
| 10 years | $34,000 | $13,527 | $47,527 |
About this tool
See how compounding can build value
Compound interest adds each period’s return to the balance, allowing later interest to build on both the original principal and prior interest. Small changes in rate and time can create large differences over long horizons.
This calculator supports daily, monthly, quarterly, semiannual, and annual compounding plus end-of-month contributions. The projection assumes a constant return and does not include taxes, fees, or market volatility.
How it works
Project compound growth in three steps
- 1Enter a starting amount
Add the money already invested or saved.
- 2Set growth assumptions
Choose a rate, timeframe, frequency, and optional monthly contribution.
- 3Review the projection
Compare principal, contributions, interest, and yearly balances.
Common questions
Compound Interest Calculator FAQ
What is compound interest?
Compound interest is calculated on the starting principal plus interest already added in earlier periods.
When are monthly contributions added?
This calculator adds each contribution at the end of the month, after that month’s estimated growth.
Does this predict actual investment returns?
No. It is a mathematical projection using a constant rate; real investments can rise, fall, charge fees, and create taxes.