Savings · growth
Compound Interest Calculator
How your money grows with interest on interest, and monthly deposits.
Your money
What is compound interest?
Compound interest is interest on your interest. Each time interest is added, the next interest is worked out on the bigger balance, so growth speeds up over time. The rule of 72 is a quick check: divide 72 by the rate to see roughly how many years your money takes to double (about 14 years at 5%).
Time matters more than the rate: starting 10 years earlier often beats saving twice as much later. Keep long-term savings in a TFSA or RRSP so the growth isn't taxed each year. See a full year-by-year projection with the investment growth calculator.
Frequently asked questions
How do you calculate compound interest?
Final amount = starting amount × (1 + rate ÷ periods) ^ (periods × years), plus the growth of any regular deposits. The calculator handles monthly deposits for you.
What is the rule of 72?
Divide 72 by the yearly interest rate to estimate how many years it takes to double your money: about 10 years at 7.2%.
Does compounding frequency matter?
A little: daily or monthly compounding earns slightly more than yearly at the same rate. The rate and the years matter much more.
Is compound interest taxed in Canada?
Outside a TFSA, RRSP or FHSA, interest is taxed every year as income. Inside a TFSA it's never taxed.
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