Compound interest formula
Without extra deposits: A = P(1 + r/n)nt. P is the start, r is the annual rate as a decimal, n is compounds per year, t is years. Extra monthly deposits are added each month before that month's growth. This is an estimate, not investment advice. Inflation and taxes are ignored.
Worked example
$10,000 at 4% compounded monthly for 10 years, no extra deposits, is about $14,908. The same start with $200 added each month is much higher because those deposits also compound.
This is not a forecast. Fees, tax on interest in a non-registered account, and inflation all reduce what you can spend. A TFSA or RRSP changes the tax, not this formula.
Common questions
What compounding do savings accounts use?
Many high-interest savings accounts compound daily and pay monthly. Monthly is a fair default.
Does this include fees?
No. Subtract any account fee from the rate or the deposits if you want a closer picture.