How this calculator works
Add a starting amount, a monthly contribution, an expected annual return and a time horizon. The calculator compounds the balance at your chosen frequency and adds contributions monthly, showing the final value, the split between contributions and interest, and a year-by-year table.
It also shows the Rule of 72 doubling time — 72 divided by your return — a fast mental check for any investment claim.
Tips for realistic projections
- Subtract fund fees from the expected return.
- Subtract inflation to see growth in today's purchasing power.
- Use conservative returns for planning; a pleasant surprise is better than a shortfall.
Frequently asked questions
Is monthly or daily compounding much better?
The difference is small. Time invested and the rate of return matter far more than compounding frequency.
Are contributions made at the start or end of each month?
This calculator adds contributions at the end of each month, a conservative convention.
Can I use this for a savings account?
Yes — enter the account's annual interest rate and choose its compounding frequency.
Results are estimates for educational purposes and depend on the assumptions you enter. They are not an offer of credit or financial advice. Last reviewed October 2026.