π Repayment Calculator
Months to payoff, total interest, and payoff date for any fixed payment.
Payoff Time
Estimates for planning only, not financial advice.
How to Use This Calculator
Enter the debt balance, its APR, and the fixed amount you pay each month. The calculator tells you how many months it takes, the total interest, the exact payoff date, and what an extra monthly amount would save.
Enter the Debt Balance and APR. Use the current statement balance and the actual rate, not a rounded guess.
Enter the Monthly Payment you actually make. It must exceed one month\'s interest (balance x APR / 12) or the debt never shrinks.
Read the payoff time, total interest, and payoff date. If the payment is too small, the calculator tells you the minimum that works.
Add an Extra amount per month to see the new payoff date and the interest saved. Even $50 changes the picture.
The Payoff Formula
The month-by-month simulation is exact for fixed payments: interest accrues on the current balance, your payment covers the interest first, and the remainder cuts principal. The closed-form version gives the same answer instantly and shows why the payment must exceed one month of interest: if P x r / payment is 1 or more, the logarithm breaks, which is math\'s way of saying "never." The calculator simulates rather than using the closed form so the final partial payment and the payoff date come out exactly right.
Worked Example
$10,000 balance at 12 percent APR, paying $200 a month. Monthly rate = 0.12 / 12 = 0.01, so the first month\'s interest is $100 and $100 goes to principal. n = -ln(1 - 10000 x 0.01 / 200) / ln(1.01) = -ln(0.5) / 0.00995 = 69.66, so 70 payments. Total interest = $3,932.37, total paid = $13,932.37. Raise the payment to $300 a month: payoff drops to 41 months, total interest drops to $2,224.95, and you save $1,707.42 while finishing 29 months sooner. The extra $100 a month costs $4,100 over the life of the plan and saves $1,707 in interest plus 29 months of debt.
Making the Payoff Happen Faster
The two levers are payment size and rate. Raising the payment is the lever you control today: automate a fixed amount above the minimum so willpower is not required each month. Lowering the rate is the lever worth one phone call: ask the issuer for a reduction, or move the balance to a lower-rate card or personal loan if the math works after fees. Pick one target date and work backward: divide the balance by the months remaining to get the required payment, add a 10 percent buffer, and automate it. What gets scheduled gets paid.
Estimates for planning only, not financial advice.
Frequently Asked Questions
How do I calculate when my debt will be paid off?
Simulate it month by month: add the month's interest (balance x APR / 12), subtract your fixed payment, and repeat until the balance hits zero. The count of months is the payoff time. For a $10,000 balance at 12 percent APR with $200 monthly payments, the simulation runs 70 months with $3,932.37 of total interest. There is also a closed form: n = -ln(1 - P x r / payment) / ln(1 + r).
What if my payment does not cover the monthly interest?
Then the balance grows every month and the debt never pays off; this is called negative amortization. On a $10,000 balance at 12 percent, monthly interest is $100, so any payment at or below $100 fails. Your payment must exceed balance x APR / 12 by a comfortable margin, or the debt outruns you. This calculator warns you when the payment is too small.
How much does an extra $100 a month save?
On a $10,000 balance at 12 percent APR, raising the payment from $200 to $300 a month cuts the payoff from 70 months to 41 months and drops total interest from $3,932.37 to $2,224.95, saving $1,707.42. The savings come from shortening the loan by 29 months of interest charges. Enter your own extra amount to see your exact numbers.
Should I use the avalanche or snowball method?
Avalanche means aiming extra payments at the highest-rate debt first, which minimizes total interest mathematically. Snowball means paying the smallest balance first, which gives quick wins that keep people motivated. Run your debts through this calculator both ways: avalanche always wins on dollars, but the best method is the one you will actually stick with for the full payoff.
Does the payoff date account for the exact day I pay?
Approximately. The calculator assumes one payment per month and interest accrued monthly, which matches how most installment loans and credit cards compute it. Real payoff dates can shift by a few days based on payment timing, daily interest accrual, and fees. Use the result for planning, and confirm the final payoff figure with your lender before sending the last payment.