Albert Einstein reportedly called it the most powerful force in the universe. When it comes to your mortgage, compound interest is working for the bank — not you.

The Golf Game That Explains Everything

Two friends bet on a round of golf. The wager starts at 10 cents per hole and doubles each time. Sounds harmless — 18 holes at 10 cents, that's pocket change, right?

By hole 6, the bet is $3.20. By hole 10, it's $51.20. By hole 15, it's $1,638.40. And hole 18? $13,107.20.

That's exponential growth. And while 100% growth per hole is extreme, the principle is the same as what happens with your home loan — the more times interest compounds, the larger the total becomes.

How It Works Against You

At the end of each month, the interest charged on your home loan is added to your balance. In the next month, interest is calculated on that new, higher balance — which includes last month's interest. Month after month, you're paying interest on interest on interest.

Over 30 years, that's 360 repetitions of this compounding cycle. On a $500,000 loan at 6%, you end up paying $1,079,000 — more than double the original amount. The extra $579,000 is the cost of compound interest working against you.

Why the Interest Rate Isn't Everything

Banks want us to focus on the interest rate. But it's not the rate alone that creates the massive cost — it's the number of times the calculation is repeated. If interest were calculated just once, a $500,000 loan at 6% would cost you $30,000 in interest. Calculated monthly for 30 years? $579,000.

This is why reducing your loan term is so powerful. Fewer years means fewer compounding cycles, which means dramatically less interest.

Make It Work For You

Compound interest can work in your favour too — in savings accounts and investments. But when you have high-interest debt, the compounding working against you almost always outweighs the compounding working for you in a savings account. Pay down the debt first.