How do I calculate how long it takes to pay off debt?

Use the formula N = log(1 - r*P/M) / log(1+r), where P is the balance, M is the monthly payment, and r is the monthly rate (APR/12/100). This calculator does it instantly above.

How much does paying an extra $100 per month save?

On a $5,000 debt at 18% APR with $150 monthly payments, an extra $100 cuts repayment from 47 to 23 months and saves around $900 in interest. Higher balances and rates amplify the savings.

What is the debt avalanche vs debt snowball method?

The avalanche method targets the highest-interest debt first, minimising total interest paid. The snowball method clears the smallest balance first for quicker wins and motivation. Both work - choose whichever you will stick to.

Should I pay off debt or invest?

If your debt interest rate exceeds expected investment returns (typically 7-10% for index funds), paying off debt first is better. Credit card debt at 18-25% APR almost always beats investing. Lower-rate debts like mortgages at 3-5% can be carried alongside investing.

Debt Payoff Calculator

Q: What is the minimum payment I must make?

Your payment must exceed the monthly interest charge (Balance x APR / 12 / 100). If it only covers interest the balance never falls. Credit cards typically set minimum payments at 1-3% of the balance or $25-$35, whichever is greater.

Find your payoff date, total interest, and savings from extra payments

Outstanding Balance $5,000

$500$25k$50k$75k$100k

Annual Interest Rate (APR) 18.0%

0%10%20%30%40%

Monthly Payment $150

$10$1.25k$2.5k$3.75k$5k

Extra Monthly Payment $0

$0$250$500$750$1,000

RESULTS

Time to Pay Off

—

Total Interest Paid

—

Total Amount Paid

—

Balance + interest

Payoff Date

—

Debt-free date

Interest (1st month)	—
Principal (1st month)	—
Total Cost of Debt	—

Year-by-Year Breakdown

Year	Balance	Principal	Interest

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Frequently Asked Questions

Use the formula N = −log(1 − r × P / M) ÷ log(1 + r), where P is the principal, M is the monthly payment, and r is the monthly rate (APR ÷ 1200). This calculator does it instantly — just enter your values above.

Your monthly payment must exceed the monthly interest charge (Balance × APR ÷ 1200). If it only covers interest the balance never falls. Credit cards typically set minimums at 1–3% of the balance or $25–$35, whichever is greater.

On a $5,000 balance at 18% APR with $150/month, adding $100 extra cuts repayment from 47 to 23 months and saves roughly $900 in interest. Higher balances and rates amplify the impact of extra payments.

The avalanche method targets the highest-interest debt first — it minimises total interest and is mathematically optimal. The snowball method clears the smallest balance first for quicker wins and motivation. Both work; choose whichever you will stick to.

If your debt interest rate exceeds expected investment returns (typically 7–10% for index funds), paying off the debt first is financially better. Credit card debt at 18–25% APR almost always beats investing. Lower-rate debts like mortgages at 3–5% can be carried alongside investing.