Compound Interest on Debt — How It Works Against You

When Compounding Works Against You

The same exponential force that grows investments destroys borrowers. On debt, compound interest means you pay interest on interest — the balance snowballs upward.

Credit Card Math: A Real Example

$5,000 balance at 24% APR (compounded daily), minimum payments only:

Year	Balance	Interest Paid That Year
0	$5,000	—
1	$5,986	$1,193
2	$7,039	$1,407
3	$8,132	$1,638
5	$10,616	$2,169
10	$16,309	—

If you paid only the minimum (~2% of balance), you’d pay over $12,000 in interest on a $5,000 purchase. The total cost: $17,000+.

The Daily Compounding Trap

Credit cards compound daily (n=365). At 24% APR:

• Daily rate: 24% ÷ 365 = 0.0657% per day
• Monthly effective rate: ~2.02%
• APY: 27.11% (not just 24%!)

That daily compounding turns a 24% APR into a real cost of over 27%.

Debt vs Investment: The Asymmetry

	Investment	Credit Card Debt
Rate	~7-10%	18-29%
Compounding	Monthly	Daily
Works for	You	The bank

Paying off a 24% credit card is equivalent to earning a guaranteed 24% return — better than any investment.

Priority Order for Debt

1. Pay minimums on everything to avoid penalties
2. Attack highest-rate debt first (avalanche method)
3. Never carry a credit card balance if you can avoid it
4. Only invest after high-interest debt is eliminated

The Bright Side

Once debt is gone, redirect those payments to investments. The same $500/month that was going to credit card payments, invested at 7% for 30 years, becomes $610,000.

Calculate exactly how long it takes to pay off your debt — and what happens after — with our compound interest calculator.