Formula
Future value depends on the starting amount, periodic rate, number of periods, and contribution amount.
Formula: FV = P(1 + r)^n + C × [((1 + r)^n - 1) / r]
Money / United States
Compound interest calculator
Enter the starting amount, contribution per period, and interest rate to estimate how a savings or investment plan grows over time.
Calculate compound growth
Value grows each period from interest plus the contribution you add at the end of that period.
The amount already in the account
Added at the end of each compounding period
Nominal annual rate
How long the money grows
The contribution schedule uses the same period as compounding.
Growth schedule
The table below shows each compounding period, the balance before interest, the contribution added, the interest earned, and the ending balance.
| Period | Starting balance | Contribution | Interest | Ending balance |
|---|---|---|---|---|
| Update the inputs to see the growth schedule. | ||||
Assumptions
- Uses USD for the example
- Contributions happen at the end of each compounding period
- The same period is used for contributions and compounding in this simplified model
Quick example
A bakery starts with $5,000, adds $500 each month, and earns 6% per year for 10 years.
Future value is about $91,037.
Total contributions are $65,000.
Interest earned is about $26,037.
Common mistakes
- Forgetting that contributions are added every period, not just once
- Using a yearly rate as if it were already a periodic rate
- Ignoring taxes or fees that may reduce the real return
Need help?
Read the full instructions and assumptions for this calculator.