What Is an Interest Rate?

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An interest rate is the price of money—either the cost to borrow it or the reward for saving it.

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• Borrowing? You pay interest.

• Saving or investing? You earn interest.

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It’s usually shown as a yearly percentage: the annual interest rate.

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Two Types of Interest

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Simple Interest

• Earned only on your original amount (called the principal).

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Example:

$1,000 at 5% for 3 years → $150 earned

Total = $1,150

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Compound Interest

• Earned on the principal and the interest already earned. This is where real growth (or pain) happens.

 

Example:

 

$1,000 at 5% for 3 years (compounded yearly) → $1,157.63

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You earned more than $150 because the base grew each year.

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This is why compound interest is often called the eighth wonder of the world.

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Why Interest Rates Matter

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Interest rates affect:

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• Credit cards

• Mortgages

• Student loans

• Savings accounts

• Investments

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A 1–2% difference may seem small—but over time, it can add up to thousands.

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How They Impact Saving vs. Borrowing

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• Higher rates are bad when you owe (debt grows faster).

• Higher rates are great when you save (money grows faster).

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Example:

Saving $10,000 at 1% for 10 years = ~$11,050
Saving $10,000 at 5% = ~$16,288

That’s a $5,000+ difference.

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Who Sets Rates in Canada?

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The Bank of Canada sets the overnight rate, which influences the prime rate banks use to price:

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• Mortgages

• Credit cards

• Loans

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When rates go up, borrowing costs more.
When they go down, borrowing is cheaper.

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Why Do Rates Change?

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The Bank of Canada adjusts rates to guide the economy:

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• If inflation is high → raise rates to slow spending

• If growth is weak → lower rates to encourage borrowing

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Think of it like a thermostat: dial up or down to stabilize conditions.

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Fixed vs. Variable Rates

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• Fixed rate = stays the same → good for stability

• Variable rate = changes with the market → riskier, but might save money

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Know what you’re signing up for.

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Make Interest Rates Work For You

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If you’re borrowing:

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• Shop for the lowest rate

• Pay off high-interest debt fast

• Use fixed rates for predictability

• Avoid compounding interest on loans if possible

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If you’re saving or investing:

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• Choose accounts with high interest

• Start early—compound interest rewards time

• Understand how often interest is added (monthly? annually?)

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Quick Trick: The Rule of 72

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A simple formula to see how long your money will take to double:

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72 ÷ Interest Rate = Years to Double

At 6% → 72 ÷ 6 = 12 years
At 8% → 72 ÷ 8 = 9 years

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Final Thoughts

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Interest can build your wealth or bury it. The difference is how you use it.

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• Borrow wisely

• Save early

• Pay attention to rates

 

The more you understand interest, the more power you have over your financial future.