By Monthly Payment
Enter the total debt amount, your APR, and how much you plan to pay each month. The calculator simulates the payoff month by month, so it correctly accounts for the balance shrinking (and the interest charged on it shrinking too) over time, down to the final, smaller payment that clears the last bit of balance.
$10,000 debt, 12% APR, $500/month Time to pay off: 1 year, 11 months Total interest: $1,213.48 By Desired Payoff Time
Enter the total debt amount, your APR, and how many months you want to take to pay it off. The calculator finds the fixed monthly payment that exactly zeroes out the balance by that month — the same formula lenders use to calculate loan payments.
Payment = P × [r(1+r)n] / [(1+r)n − 1] Example: $10,000 debt, 12% APR, 24 months → $470.73/month P is the debt amount, r is the monthly interest rate (APR ÷ 12), and n is the number of months. At 0% APR, this simplifies to just the debt amount divided by the number of months, since there's no interest to account for.
Frequently asked questions
What if my monthly payment doesn't cover the interest?
If your payment is smaller than the interest charged each month, the balance grows instead of shrinking — you'd never pay it off no matter how long you kept paying. The calculator detects this and tells you directly rather than showing a misleading number.
Why is the total interest different between the two tabs for a similar payoff time?
They shouldn't be, for the same debt, APR, and number of months — both tabs are solving the same underlying amortization schedule, just from different starting points (payment amount vs. payoff time). Any difference you see is because the number of months doesn't divide evenly, so the "By Monthly Payment" tab's final month may be a smaller partial payment.
Does this account for extra or variable payments?
No — this calculator assumes a fixed monthly payment (or a fixed target payoff date) with no extra lump-sum payments along the way. For juggling multiple debts or savings goals with varying contributions, see the Savings Goals Calculator instead.