One thousand dollars.
That is a number many teenagers actually have, or could have, by the time they're 16. Savings from a summer job. Birthday money accumulated over years. A few months of careful spending.
What you do with that $1,000 matters more than almost anything else about your financial future. A thousand dollars isn't life-changing money on its own. What makes it matter is what happens to it over the next few decades.
This is about compound interest, and why the window you're standing in right now is one you cannot get back.
What Compound Interest Actually Is
Simple interest is straightforward. You put $1,000 in an account earning 5% per year. At the end of year one, you have $1,050. The bank calculates interest on your original deposit, every year, forever.
Compound interest is different.
With compound interest, your earnings are added to your balance. Next year's interest is then calculated on that larger balance. The interest earns interest. That might sound like a minor distinction. Over decades, it becomes the entire game.
Here is what $1,000 looks like at 7% average annual return, compounding, over time:
- Year 1: $1,070
- Year 5: $1,403
- Year 10: $1,967
- Year 20: $3,870
- Year 30: $7,612
- Year 40: $14,974
- Year 50: $29,457
You put in $1,000. Fifty years later, without adding another dollar, you have nearly $30,000.
There's no trick to it. It's just arithmetic doing its thing over a long stretch of time.
Each year's growth becomes part of the base for next year's growth. The number being multiplied keeps getting larger. The longer you let it run, the faster it seems to accelerate.
Why Your Age Right Now Is Actually an Advantage
Here is the thing most adults wish someone had told them at 16.
Compound interest doesn't reward skill or luck or picking the right stock. It rewards time. The longer your money is invested, the more the compounding does its work. And the one thing that gives you more time than anything else is starting earlier.
Consider two scenarios. You start investing $100 per month at 16. By the time you're 65, you've contributed $58,800 over 49 years. At a 7% average annual return, that $100 per month has grown to roughly $500,000.
Now imagine someone who waits until 26 to start. Same $100 per month. By 65, they've put in $46,800 over 39 years. Their total at the same 7% average? Around $244,000.
The early starter contributed only $12,000 more. Their final balance is more than double.
Starting at 16 instead of 26 roughly doubles your final number.
That extra $256,000 didn't come from earning more or investing smarter. It came from ten years of head start, and the compounding those ten years made possible.
The years between 16 and 26 look like a short stretch of life. In compounding terms, they are among the most valuable years you will ever have.
The Rule of 72
Here is a useful mental shortcut worth knowing.
Divide 72 by your expected annual return, and you get roughly how many years it takes your money to double.
At 7% return: 72 / 7 = about 10 years to double.
If you invest $1,000 at 16 and earn 7% annually, here is what that looks like:
- Age 26: roughly $2,000
- Age 36: roughly $4,000
- Age 46: roughly $8,000
- Age 56: roughly $16,000
- Age 66: roughly $29,000
Now wait until 26 to invest that same $1,000:
- Age 36: roughly $2,000
- Age 46: roughly $4,000
- Age 56: roughly $8,000
- Age 66: roughly $16,000
One missed decade. About half the money.
Earning more later is always possible. Getting those years back is the one thing you can't do.
Where to Put It in Canada
Canada has a tool built specifically for this: the Tax-Free Savings Account (TFSA).
Starting at 18, every Canadian resident gets $7,000 of annual contribution room in a TFSA. Money invested in a TFSA grows completely tax-free. No tax on the gains. No tax when you take it out. The government takes nothing.
Compare that to a regular savings account. Earn $200 in interest there and the CRA treats it as income. You report it, you pay tax on it at your marginal rate. Inside a TFSA, that same $200 is just yours.
For a teenager with a few hundred or a few thousand dollars to invest, a TFSA is where that money belongs. A simple, low-cost index ETF inside a TFSA gives you broad market exposure, compound growth, and zero tax drag. It is one of the strongest financial tools available to ordinary Canadians, and the earlier you start using it, the more it works for you.
If you're 13 to 17 right now: you can't open a TFSA yet, but you can build the habit by saving in a regular bank account. When you turn 18, transfer that money in and let it grow from there. You lose nothing by starting now.
If you're 18 or 19: open a TFSA first, before anything else. There's a full guide on what a TFSA is and how to open one in this same section.
The Small Amounts Are Not Small
Here is what trips a lot of teenagers up.
They see $40 from a birthday or $80 left over after a paycheque and think: this is too small to matter. I'll start properly when I have real money.
That thinking costs more than almost any other financial mistake you can make right now.
$100 invested at 16, left completely alone, grows to roughly $2,000 by the time you're 26. Still not impressive on its own. But $100 every month from age 16 to 65? That's roughly $500,000 at retirement. Those small, regular amounts add up to something most people would call life-changing.
The habit matters more than the amount. The teenager who moves $50 into savings the day their paycheque arrives, every single time, is building something real. The one waiting to start "properly" when the amounts feel significant is watching compounding time evaporate.
A small amount you actually save every time beats a big amount you keep promising yourself you'll get around to.
A Word on the 7% Number
The examples in this article use 7% as the assumed annual return. That's a reasonable historical average for a diversified portfolio of stocks over long periods, often referenced when talking about broad market index funds.
It is not guaranteed. Some years markets go up 20%. Some years they drop 15%. The 7% is an average over decades, not a promise in any given year.
What that means for you: don't panic when the market has a bad year. Compound interest works over the long run, and the long run is exactly what you have right now. Selling when prices drop, or avoiding investing because the market feels uncertain, is what turns the math against you. Hold steady. Keep contributing. Let time do what time does.
Your Next Step
You don't need a lot to start. You need to start.
This week: open a savings account if you don't have one. Move whatever you have into it, even if it's $50 or $100. Set up an automatic transfer so a fixed amount goes in every time you get paid.
If you're 18 or older, open a TFSA and put the money there.
Write down how much you invested and the date you started. Not for any complicated reason. Just so someday you can look back and see what that one decision became.
The math is not complicated. Time is the thing. And you have more of it right now than you ever will again.