Compound Interest Calculator

See how your savings grow with compound interest over time.

$3,008,507

Final amount

after 20 years

Total paid in
Your own money
$1,300,000
Interest earned
Return
$1,708,507
Time to double
Rule of 72
10.3years
Growth per year
Average
$145,425

Growth over time

yr 1
$169,192
yr 5
$499,727
yr 10
$1,066,390
yr 15
$1,869,706
yr 20
$3,008,507
Paid inInterest

What is compound interest?

Compound interest means that interest added to a balance can itself earn interest later. The starting amount, deposits, rate and time all affect the result. Change one value at a time to see what drives growth.

Concept illustration: a balance with reinvested interest can grow faster over time. These curves do not show your selected values.

How it is calculated

Without new deposits, the formula is A = P × (1 + r/n)^(n×t): P is the principal, r the annual rate as a decimal, n periods per year and t years. Here, monthly deposits are grouped per interest period and added at its end. At 0% interest, only deposits are added.

Is the return guaranteed?

No. The calculation uses a fixed rate that you choose. It is a scenario and excludes tax, fees and inflation.

Why does the number of years matter?

More periods give previously earned interest more time to grow. Compare equal deposits and rates over different durations to isolate the effect of time.

Sources and further reading