Debt Payoff Calculator
Enter your debts, choose your strategy, and see exactly when you'll be debt-free — and how much interest you'll save. Model windfalls, balance transfers, and income changes.
Start with a template:
Your Debts
Payoff Strategy
Avalanche Method
Pay minimums everywhere. Focus all extra money on the highest-APR debt first.
Snowball Method
Pay minimums everywhere. Focus all extra money on the smallest balance first.
Even $50–100/month extra dramatically cuts payoff time and total interest.
Scenarios (optional)
Debt-free by: —
Balance Over Time
This link encodes your exact numbers so you can bookmark it or share it.
Calculate is great. Tracking is better.
Sign up free and LazeeFish will auto-split every payment into principal and interest. Your calculator scenario becomes real data as you pay down debt.
How debt payoff math actually works
Every month, your lender multiplies your remaining balance by your monthly interest rate (APR ÷ 12) to calculate that month's interest charge. That charge is added to your balance before your payment is applied. This is the mechanic that makes debt so persistent.
For example, a $5,000 credit card at 22.99% APR charges $95.79 in interest in month 1. If your minimum payment is $100, only $4.21 pays down the principal. At that rate, it would take over 12 years and cost nearly $5,000 in interest to pay off. Double the payment to $200/month, and it's done in 2.5 years with only $1,100 in interest — a 78% reduction in total interest from one simple change.
Why minimums keep you in debt so long
Most card issuers set the minimum payment at 2–3% of the balance. As the balance falls, so does the minimum — which means less goes to principal, not more. The bank designs minimums to maximize the interest you pay over time, not to help you get out of debt quickly.
The snowball vs. avalanche decision
Both methods pay minimums on all debts and focus every extra dollar on one debt at a time. They differ only in how they choose the "focus" debt:
| Avalanche | Snowball | |
|---|---|---|
| Focus debt | Highest APR first | Smallest balance first |
| Total interest paid | Minimum possible | Usually slightly more |
| First payoff | Sometimes slower | Fast — quick psychological win |
| Best for | Maximizing savings if you'll stick to the plan | Keeping motivation if you need visible wins |
| Difference in practice | Usually $200–$2,000 depending on the debt mix. Use this calculator to see the exact gap for your numbers. | |
How extra payments compound over time
Extra payments don't just reduce next month's interest — they permanently lower the balance against which every future month's interest is calculated. A $100 extra payment in month 1 saves approximately $100 × APR in interest over the remaining life of the loan — sometimes several times over on a long high-rate debt. This is why financial advisors consistently rank eliminating high-interest debt as one of the highest-return "investments" available.
Windfalls: the fastest debt-payoff accelerator
A one-time lump-sum payment — tax refund, work bonus, inheritance, sale of an asset — can have a disproportionate impact because it hits the balance early, when the remaining term (and therefore the interest at risk) is longest. A $2,000 windfall applied in month 3 to a high-rate card might save $3,500 in interest over the remaining payoff. Use the Windfall scenario above to see the exact math for your situation.
Balance transfers: when the math works
A balance transfer moves a balance to a new card with a lower APR — often a 0% promotional rate for 12–21 months. The upfront fee (typically 3–5%) is the cost of the arbitrage. The deal makes sense when: the fee is less than the interest you'd pay in the same period at the original rate; and you can realistically pay it off before the promotional period ends. If you can't pay it off in time, the reverted APR (often 25%+) may erase the gains. Model it with the Balance Transfer scenario above — the calculator adds the fee to the starting balance and resets the APR at the specified month.