Finance calculator
How much will my money grow?
Compound interest rewards consistency. Use this calculator to estimate how your savings or investments can grow over time with monthly contributions.
Try the calculator
Enter your starting balance, contribution, rate, and time horizon.
How compounding works
Compound interest means you earn returns on both your original principal and the interest already earned. The longer the time horizon, the bigger the effect of compounding.
The formula for a balance with monthly contributions is: A = P(1+r)^n + PMT x ((1+r)^n - 1) / r. Here, r is the monthly rate and n is the number of months.
Example scenario
Start with $5,000, add $200 per month, earn 6% annually, and invest for 20 years. The balance grows to about $101,000, with most of the growth driven by consistent contributions and compounding.
What this means
- - Increase contributions when income rises.
- - Start early to give compound interest more time.
- - Keep fees low so more returns stay invested.
- - Stay consistent through market ups and downs.
What to do next
Set a monthly contribution you can keep for years. Small increases matter more than one-time deposits.
FAQ
How often does the calculator compound?
This calculator compounds monthly, which is a common assumption for savings accounts and investment projections.
Are contributions added at the end of each month?
Yes. Monthly contributions are added at the end of each period in this model. That keeps the math consistent and easy to understand.
Does it account for taxes or inflation?
No. The results are before taxes and inflation. You can adjust the interest rate to estimate a net or real return if needed.