Savings & compound interest calculator
Start with what you've got, add a bit each month, and see where you'll be.
Where the money comes from
Year-by-year table
The formula
FV = P(1 + i)n + D × ((1 + i)n − 1) ÷ iP is the starting balance, D the monthly deposit (made at the end of each month), n the number of months, and i the monthly growth rate for your compounding choice: (1 + rate ÷ k)k÷12 − 1.
Worked example
$10,000 to start, $500 a month, 5% compounded monthly for 10 years: you deposit $70,000 in total and end up with $94,111, so $24,111 of it is interest.
Common questions
What is compound interest?
Interest on your interest. Each period, the interest you've earned is added to your balance, so next time you earn interest on a bigger amount. Over long periods this snowballs.
Monthly or annual compounding – does it matter?
A little. At 5% a year, monthly compounding works out to about 5.12% effective, and daily to about 5.13%. Regular deposits and time matter far more.
Is interest on savings taxed?
Yes. Interest is added to your taxable income. This calculator shows returns before tax.
What rate should I use?
Use your account's ongoing rate, not a short-term bonus or intro rate. For long-term investing, many people use a more conservative figure than recent returns.