Put long-term money to work
Compound interest calculator
See what happens when you keep adding money and give it time to earn on top of itself. The calculator separates the money you put in from the growth it could produce.
Build your scenario
Start with what you can repeat. Change any number and the result updates instantly.
What you have today
The amount you plan to keep adding
Keep the horizon realistic
An assumption, not a promise
Estimated balance after 25 years
$169,895
$75,000 comes from money you put in. $94,895 is estimated growth from keeping that money working.
Money you added
$75,000
Growth from your money
$94,895
Compounding at work
56%
of the ending balance is estimated growth
By about year 22, estimated growth becomes larger than everything you have contributed to that point. That is the handoff: your money starts doing more of the work.
In today's dollars
Uses 2% annual inflation
$103,556
Watch the gap widen
The distance between what you added and the total balance is the estimated growth.
Small increases get years to compound too
Another $100 each month adds about $67,958 to the estimated ending balance in this scenario.
See a range, not a promise
Two percentage points lower or higher changes the picture.
Lower
$127.6K
4% / year
Your estimate
$169.9K
6% / year
Higher
$228.7K
8% / year
Assumptions used
Monthly contributions are added at the beginning of each month. The main result is nominal; the today's-dollar value uses 2% annual inflation. Fees, taxes, and changing contribution amounts are not included. Returns and inflation vary.
Why this matters
Compounding is level one of building wealth.
You earn a dollar once. If long-term money stays invested and earns a return, that dollar can keep contributing after you do. Leave the return invested and the next return is earned on a larger base.
Early on, your contributions do most of the work. Over time, the balance can reach a point where the growth is adding more than you are. That handoff is the part worth understanding.
This is not a rule to invest every dollar. Cash for bills, emergencies, and near-term goals has a job too. The idea applies to money you can leave working for years.
Keep adding
Regular contributions keep feeding the balance.
Leave the return in
Growth stays invested instead of being pulled out.
Let time repeat it
New returns are earned on your money and prior growth.
A repeatable example
$250/month
for 25 years at an illustrative 6% annual return
You add
$75,000
Growth adds
$94,895
Estimated balance
$169,895
Use it well
Use numbers you can actually live with.
Start with what you have
Use your current long-term balance, or zero if you are starting fresh.
Pick an amount you can repeat
A smaller monthly contribution you actually keep making is more useful than an ambitious number you will not.
Give it enough time
Compounding needs time. Try 10, 20, and 30 years and watch how the gap changes.
Stress-test the return
The rate is an assumption. Compare the lower and higher scenarios instead of trusting one number.
Method and assumptions
What the calculator is actually doing.
The calculator treats the percentage you enter as the effective return for one full year. It converts that annual assumption to an equivalent monthly rate, adds your monthly contribution at the beginning of each month, and then applies the monthly growth rate.
rm monthly return · ra annual return · B balance · C monthly contribution · Y years
This is an illustration, not a forecast. Returns and inflation vary, losses are possible, and the estimate excludes fees and tax. The Financial Consumer Agency of Canada explains how compounding frequency affects savings; the Bank of Canada describes its own investment-calculator results as reference only.
Common questions
A few things worth knowing before you trust the number.
What is compound interest?
It is the return-on-return effect. Your original money can earn a return, then the return stays in the account and can earn a return too. Over enough time, that second layer can become a large part of the ending balance.
Why does starting earlier matter so much?
Because time gives each contribution more chances to earn and then re-earn. A dollar added earlier has more compounding periods than the same dollar added later.
Can I use it for a TFSA, RRSP, or savings account?
You can use it to illustrate growth in any account, but it does not model TFSA contribution room, RRSP tax deductions or withdrawals, savings-account rate changes, or account-specific tax treatment.
What annual return should I enter?
There is no universally correct rate. Use a rate that fits what you are modelling, then test several outcomes. A fixed savings product and a diversified investment portfolio have different risks, fees, and expected returns.
Deciding where the money should go? Read the practical guide to TFSA versus RRSP in Canada.