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Compound Interest Calculator

See exactly how your savings or investments grow over time with the power of compounding. Adjust rate, contributions, and time period to plan your financial future.

Home›Compound interest calculator

Compound Interest Calculator

See how your money grows over time with the power of compounding. Start early, grow faster.

Investment details
$
$
%
yrs
Results
Future value
$0
after 20 years
Total deposited
$0
Interest earned
$0
Starting amount
$0
Return on investment
0%
Deposits vs Interest
Deposited 0% Interest 0%
Year-by-year growth
YearDepositedInterest earnedTotal value

How compound interest is calculated

01
Enter your starting amount
This is your initial deposit or lump sum investment. It does not have to be a large number — compound interest works even on small starting amounts given enough time.
02
Add monthly contributions
Regular monthly contributions dramatically accelerate growth. Even a small consistent contribution added to compound growth produces remarkable results over time.
03
See year-by-year growth
The growth table shows your total deposited, interest earned, and portfolio value for each year — so you can see compound growth accelerating over time.

The formula used is: A = P(1 + r/n)^(nt) + PMT × [(1 + r/n)^(nt) − 1] / (r/n) — where P is the principal, r is the annual interest rate, n is the compounding frequency, t is time in years, and PMT is the monthly contribution.

The most powerful factor in compound interest is time. The earlier you start, the more years your money has to compound. A 10-year head start can be worth more than doubling your monthly contributions later on.

The compounding frequency also matters — monthly compounding yields slightly more than annual compounding at the same stated rate, because interest is added and begins earning returns more frequently.