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Find how long a fixed monthly payment takes to clear a balance — and what it costs.
Find how long a fixed monthly payment takes to clear a balance — and what it costs.
Enter values above and click Calculate — results will appear here with the formula explained.
Every month, interest is charged on the remaining balance; whatever remains of your payment reduces principal. The formula above inverts that process to find when the balance hits zero given a fixed payment. It is the same amortization mathematics as mortgages, run in reverse: instead of solving for payment given a term, it solves for term given a payment.
The critical insight is the floor: if your payment doesn't exceed the first month's interest, the balance never falls and the debt is permanent. An $8,000 balance at 22.9% APR accrues about $153 in monthly interest — a $160 payment retires $7 of principal and takes decades, while $300 retires real principal from day one. Near that floor, small increases in payment produce enormous improvements — the highest-leverage dollars in personal finance.
Snowball versus avalanche is the strategy layer on top of this math. Avalanche (highest APR first) minimizes total interest paid — always, mathematically. Snowball (smallest balance first) clears whole debts sooner, delivering motivational wins that keep people paying. Studies on debt behavior repeatedly find completion beats optimization: the method you sustain for 24 months outperforms the 'better' method you abandon in six. Pick avalanche if you are analytical, snowball if you have quit before.
Minimum payments are engineered to maximize lender profit, not your freedom: typical formulas (1–2% of balance or $25+) keep payments near the interest floor for years. Paying only minimums on that $8,000 balance can stretch repayment past a decade with interest rivaling principal. Any fixed payment above the minimum collapses the timeline — the calculator's scenario comparison exists to make that collapse visible and motivating.
Balance transfers and consolidation can lower the rate variable directly: 0% intro-APR cards (usually 12–21 months with 3–5% transfer fees) or lower-rate personal loans replace 20%+ APR with single digits. The math only works if new borrowing stops — transferring $8,000 then re-spending $3,000 leaves more debt at two rates. Model the consolidated payment here with the new rate and a fixed payoff date before moving balances.
Protect the payoff plan from its two classic killers: new charges on cleared cards (freeze the card, keep it open for credit history) and lifestyle creep as minimums fall. Automate the chosen payment for the day after payday, direct every freed minimum from a cleared debt into the next target, and the same dollars that once serviced interest start compounding your net worth instead.
Find how long a fixed monthly payment takes to clear a balance — and what it costs. Formula: n = −ln(1 − r·B/P) ÷ ln(1 + r), where B is balance, P payment, r the monthly rate.
Every month, interest is charged on the remaining balance; whatever remains of your payment reduces principal. The formula above inverts that process to find when the balance hits zero given a fixed payment. It is the same amortization mathematics as mortgages, run in reverse: instead of solving for payment given a term, it solves for term given a payment.
The critical insight is the floor: if your payment doesn't exceed the first month's interest, the balance never falls and the debt is permanent. An $8,000 balance at 22.9% APR accrues about $153 in monthly interest — a $160 payment retires $7 of principal and takes decades, while $300 retires real principal from day one. Near that floor, small increases in payment produce enormous improvements — the highest-leverage dollars in personal finance.
Snowball versus avalanche is the strategy layer on top of this math. Avalanche (highest APR first) minimizes total interest paid — always, mathematically. Snowball (smallest balance first) clears whole debts sooner, delivering motivational wins that keep people paying. Studies on debt behavior repeatedly find completion beats optimization: the method you sustain for 24 months outperforms the 'better' method you abandon in six. Pick avalanche if you are analytical, snowball if you have quit before.
Minimum payments are engineered to maximize lender profit, not your freedom: typical formulas (1–2% of balance or $25+) keep payments near the interest floor for years. Paying only minimums on that $8,000 balance can stretch repayment past a decade with interest rivaling principal. Any fixed payment above the minimum collapses the timeline — the calculator's scenario comparison exists to make that collapse visible and motivating.
Balance transfers and consolidation can lower the rate variable directly: 0% intro-APR cards (usually 12–21 months with 3–5% transfer fees) or lower-rate personal loans replace 20%+ APR with single digits. The math only works if new borrowing stops — transferring $8,000 then re-spending $3,000 leaves more debt at two rates. Model the consolidated payment here with the new rate and a fixed payoff date before moving balances.
Protect the payoff plan from its two classic killers: new charges on cleared cards (freeze the card, keep it open for credit history) and lifestyle creep as minimums fall. Automate the chosen payment for the day after payday, direct every freed minimum from a cleared debt into the next target, and the same dollars that once serviced interest start compounding your net worth instead.
An $8,000 balance at 22.9% APR with $300/month pays off in 33 months with about $2,900 interest. Pushing the payment to $400 cuts the timeline to 23 months and interest to roughly $1,700 — $100 more monthly saves $1,200 and 10 months. A transfer case: moving the same balance to 0% for 18 months (3% fee = $240) with $450/month clears it in 18 months for $240 total cost versus $2,900 — if and only if no new charges land on either card.
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
Last reviewed: September 2026 · Report an error