Loan Payoff Calculator
Months to pay off a balance and total interest at a fixed payment.
Time to pay off
3y 0m
36 payments
Total interest
$2,533.46
Total paid
$10,533.46
Your balance falls to zero over 3y 0m — faster near the end as more of each payment attacks principal.
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Plain-English insight on your numbers
Get a personalized explanation of what these results mean — and how to improve them.
How the Loan Payoff Calculator works
The Loan Payoff Calculator tells you exactly how many months it will take to eliminate a debt balance and how much total interest you will pay when you make a fixed monthly payment — essential knowledge for anyone managing credit card debt, personal loans, or any revolving balance.
At its core, this calculator solves for the number of payment periods required to reduce a principal balance to zero given a fixed periodic payment and a known annual interest rate. Each month, your lender applies a portion of your payment to accrued interest first, and whatever remains chips away at the principal. Because the interest charge shrinks as the balance shrinks, a slightly larger fixed payment creates a disproportionately shorter payoff timeline — a non-linear relationship that surprises most borrowers.
The key inputs are your current outstanding balance, the annual interest rate (APR), and the fixed monthly payment you plan to make. The calculator converts the annual rate to a monthly periodic rate, then uses the standard loan amortization formula to count the exact number of months until the balance hits zero. It also accumulates total interest paid across all periods, giving you a true cost-of-debt figure that's often far larger than borrowers expect — especially on high-APR credit cards where rates commonly exceed 20%.
The most powerful use of this tool is running side-by-side payment scenarios. For example, if you carry a $5,000 balance at 22% APR and pay only the typical minimum of $100 per month, you might need over 8 years and pay more than $4,500 in interest. Bumping that payment to $200 per month can cut the timeline to under 3 years and slash interest costs by more than half. This 'what-if' framing is where the calculator delivers its greatest value — making the abstract cost of debt viscerally concrete.
A common mistake is confusing APR with a monthly rate. The monthly periodic rate is APR divided by 12, and compounding works against you every single month, not just annually. Another pitfall is not accounting for fees or penalty rates that some lenders add after a missed payment — if your effective rate changes, recalculate immediately. Finally, ensure your fixed payment always exceeds the monthly interest charge; if it does not, the balance will grow rather than shrink, and no payoff date exists.
Formula
n = -ln(1 - (r × PV) / PMT) / ln(1 + r) Where: n = number of months to pay off, r = monthly interest rate (APR / 12), PV = present value (current balance), PMT = fixed monthly payment. Total Interest = (PMT × n) - PV
Pro tips
- Always pay more than the interest-only amount — even $20–$50 above the minimum can shave months off your payoff date and save hundreds in interest.
- Use the calculator to set a target payoff date first, then back-calculate the fixed payment needed to hit that deadline rather than defaulting to whatever minimum the lender sets.
- If you have multiple debts, run this calculator on each one. Rank them by either highest interest rate (avalanche method) or smallest balance (snowball method) to build a sequenced payoff plan.
- After making extra payments or a lump-sum payment toward principal, re-run the calculator with your updated balance to see your new, shorter payoff timeline — this reinforces positive momentum.
- Watch for deferred-interest promotions: if you do not pay the full balance before the promotional period ends, retroactive interest can be added all at once, resetting your payoff math entirely.
Key terms
- Principal Balance
- — The outstanding amount of debt you currently owe, excluding any future interest charges.
- APR (Annual Percentage Rate)
- — The yearly interest rate charged on your loan balance, which is divided by 12 to calculate the monthly periodic rate used in each payment cycle.
- Monthly Periodic Rate
- — The APR divided by 12; the actual rate applied to your remaining balance each month to calculate that month's interest charge.
- Amortization
- — The process of gradually paying down a loan through scheduled payments that cover both accruing interest and a portion of the principal balance.
- Total Interest Paid
- — The cumulative sum of all interest charges across every payment period, representing the true cost of carrying the debt to full payoff.
- Minimum Payment
- — The smallest payment a lender requires each month, often calculated as a small percentage of the balance, which typically extends the payoff timeline dramatically and maximizes interest paid.
