Compound Interest Calculator
See how consistent monthly contributions and compound growth can transform your wealth over time.
Your Compound Growth
Adjust the inputs to see how your investments could grow over time.
Starting Amount
Monthly Contribution
Annual Growth Rate
7%Timeline
30 years5YR
$43K
10YR
$97K
20YR
$281K
30YR
$651K
Total Contributed
$185,000
Investment Growth
+$465,568
Final Balance
$650,568
Compound growth did more than you did: 72% of your balance came from returns.
Cost of waiting
The same plan started 10 years later, ending in the same year: $5,000 to start and $500/mo at 7%, for 20 years instead of 30.
Start now
$650,568
$185,000 put in
Start in 10 yrs
$280,657
$125,000 put in
Starting now ends with $369,911 more.
To reach the same $650,568, the later start needs $1,210/mo, which is $710 more per month.
Assumes monthly compounding and a steady return. For illustration only, not financial advice.
Track your investments alongside your full net worth
Start Growing Your Net WorthHow Compound Interest Works
Compound interest is interest earned on both your original investment and on interest you've already earned. It's the reason Albert Einstein (allegedly) called it the "eighth wonder of the world."
The magic of compounding is that it accelerates over time. In the early years, most of your balance comes from your contributions. But as your portfolio grows, the growth on your growth starts to dominate. That's the inflection point, when your money is working harder than you are.
The Rule of 72
A quick way to estimate how long it takes to double your money: divide 72 by your annual return rate. At 7% returns, your money doubles roughly every 10.3 years. At 10%, every 7.2 years. This simple rule shows why even small differences in return rate, or starting a few years earlier, make an enormous difference over decades.
Why Consistency Matters More Than Amount
The habit of investing consistently matters more than the amount, especially early on. At a 7% return, someone who invests $200/month for 30 years ends with about $244K. Someone who waits 10 years and then invests $400/month for 20 years ends with about $208K, even though they put in $24K more.
Ready to Start Building?
Track your real net worth over time and watch compound growth in action.
Start Growing Your Net Worth