Compound Interest Calculator
See how a one-time amount plus regular contributions grows with compound interest over time — choose your rate, contribution, compounding frequency and horizon, and view the result in today’s dollars. Free, and works entirely in your browser.
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Frequently asked questions
What is compound interest?
Compound interest is interest earned on both your original money and on the interest it has already earned. Over long periods this “interest on interest” is what drives most of an investment’s growth.
How does compounding frequency affect the result?
More frequent compounding (e.g. monthly vs. annually) means interest is added to your balance sooner, so it starts earning its own interest sooner. The effect is real but usually small compared with the interest rate and time horizon.
What does the “today’s dollars” view show?
It discounts the future balance by your assumed inflation rate, showing roughly what that amount would buy in today’s money. A dollar in 25 years buys less than a dollar today.
Is this the same as investment returns?
No. This uses a single fixed interest rate. Real investment returns vary year to year. For a market-based projection across Canadian ETFs, use the ETF portfolio calculator.
Are my numbers saved?
Your last inputs are saved in your browser (localStorage) so the tool remembers them next visit. Nothing is sent to a server — there are no accounts and no tracking that phones home.