💹 Investment Growth Calculator
Project portfolio growth with recurring investing, compound returns, and long-term assumptions.
Compound Interest Calculator
Use this free compound interest calculator to see how an initial investment and recurring monthly contributions can grow over time. It is built for common searches like compound interest calculator, investment growth calculator, and how much will my money grow at 7%.
Interactive calculator
$
$
% / yr
years
Final Balance
$196,665
Total Interest
$114,665
Total Contributed
$82,000
Return Multiple
2.40×
Growth over 20 years
Balance Contributions
How the math works
Formula
FV = PV(1 + r/n)^(nt) + PMT × [(1 + r/n)^(nt) − 1] / (r/n)
- FVFuture value — the ending balance
- PVPresent value — starting balance
- rAnnual interest rate as a decimal (e.g. 0.07 for 7%)
- nCompounding periods per year (12 for monthly)
- tNumber of years
- PMTRecurring contribution added each period
Plain English
Each month your balance earns a small slice of the annual rate. Because those earnings are added to your principal, the following month's earnings are slightly larger. Over decades, this snowball effect means most of your ending balance comes from growth, not contributions. A $10,000 investment at 7% for 30 years with $200/month grows to roughly $264,000 — about $120,000 in contributions and $144,000 in compound growth.
How to use this calculator
- 1
Enter your starting balance, monthly contribution, expected annual return, and number of years.
- 2
Review the final balance, total contributions, and total interest earned.
- 3
Adjust the contribution amount or time horizon to compare different growth scenarios.
Why this number matters
Compound growth is one of the biggest drivers of long-term wealth. A small change in contribution amount, annual return, or time horizon can materially change your ending balance, which makes this calculator useful for retirement planning, brokerage investing, and long-term savings decisions.
What this calculator helps you answer
- •How much will $10,000 grow in 20 or 30 years?
- •How much do monthly contributions add to long-term returns?
- •What share of the ending balance comes from contributions versus growth?
Frequently asked questions
What is compound interest?+
Compound interest means your returns earn additional returns over time. Instead of growing only on your original principal, your balance grows on prior gains as well.
How often should I compound returns in a calculator?+
For planning, monthly compounding is a reasonable default because it aligns with recurring contributions and most long-term investing assumptions.
What return rate should I use?+
That depends on your asset mix and risk tolerance. Many long-term stock market projections use assumptions around 6% to 10% before inflation, but your actual return can vary significantly.
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