Debt Payoff Calculator
What this calculator does
This calculator estimates how long it will take to pay off your debts and how much total interest you will pay based on your balances, interest rates, and monthly payment amounts. It helps you compare payoff strategies—particularly the avalanche and snowball methods—so you can choose the approach that saves the most money or keeps you most motivated.
Carrying high-interest debt from credit cards, personal loans, or medical bills can feel overwhelming. This tool turns the vague anxiety of "how long will this take?" into a concrete timeline with month-by-month projections. Enter each debt's balance, interest rate, and minimum payment, plus any extra monthly amount you can put toward debt, and see exactly when you will be debt-free.
Understanding the real cost of debt—the total interest over the life of repayment—is often the wake-up call that motivates people to accelerate payments and change spending habits.
How to use it
- Enter each debt name, balance, interest rate (APR), and minimum monthly payment.
- Enter any extra monthly payment you can afford above the minimums.
- Select a payoff strategy: Avalanche (highest rate first) or Snowball (smallest balance first).
- Review the payoff timeline, total interest paid, and month-by-month breakdown.
Formulas used
Monthly interest on a balance: Interest = Balance × (APR / 12)
Principal paid per month: Principal = Payment − Interest
Avalanche method: Extra payments go to the debt with the highest interest rate first. Once that debt is paid off, its payment rolls into the next highest rate. This minimizes total interest paid.
Snowball method: Extra payments go to the debt with the smallest balance first. Once paid off, its payment rolls into the next smallest balance. This produces quick wins that build psychological momentum.
Examples
Example 1 — Two credit cards (Avalanche): Card A: $5,000 at 22% APR, $150 min. Card B: $3,000 at 16% APR, $90 min. Extra $200/month. Avalanche directs the extra $200 to Card A first. Payoff ≈ 19 months, total interest ≈ $1,420.
Example 2 — Same debts (Snowball): Snowball directs the extra $200 to Card B (smaller balance) first. Payoff ≈ 20 months, total interest ≈ $1,580. You pay ~$160 more in interest but eliminate Card B in just 8 months for a psychological boost.
Example 3 — Mixed debts: Student loan: $12,000 at 5%, $200 min. Credit card: $4,000 at 24%, $100 min. Car loan: $8,000 at 6.5%, $250 min. Extra $300/month, avalanche. The extra $300 hits the 24% card first. Total payoff ≈ 28 months, total interest ≈ $2,150.
Tips and common mistakes
- Avalanche saves the most money mathematically, but snowball keeps you motivated by eliminating debts quickly. Choose the method you will actually stick with.
- Always pay at least the minimums on every debt to avoid late fees and credit score damage.
- Avoid adding new debt while paying off existing balances—otherwise you are filling a bucket with a hole in it.
- Consider balance transfer offers (0% intro APR) for high-rate cards, but watch for transfer fees (typically 3–5%) and the rate after the promo period ends.
- Round up payments. Paying $255 instead of $250 adds up significantly over months and years.
- Windfalls accelerate payoff. Tax refunds, bonuses, or side income applied to debt can shave months off your timeline.