Free debt payoff calculator with extra payments compares payoff time, total interest, and savings for one fixed-rate balance.
This debt payoff calculator shows how a fixed extra amount added to every monthly payment can change the payoff time and interest cost of one existing balance. It is designed for people who know their current balance, APR, and required monthly payment.
Enter the balance from your statement, the annual percentage rate, the payment you already plan or are required to make, and the extra amount you can pay each month. The results compare the required-payment path with the required payment plus your extra amount.
The calculation assumes no new charges, fees, missed payments, or rate changes. It is a monthly estimate for one debt, not a multi-debt snowball or avalanche plan.
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Use the current principal or statement balance for one debt, from $0 to $1 billion. A larger balance generally takes longer and costs more interest.
18%
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Enter the current annual percentage rate from 0% to 100%. A higher APR increases monthly interest and can prevent a small payment from reducing principal.
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Enter the monthly amount you would pay without the extra amount, up to $10 million. It must exceed monthly interest to produce a payoff estimate.
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Enter the additional amount you can consistently add each month, up to $10 million. A larger extra payment usually shortens payoff time and lowers interest.
Example
Example: Add $100 Each Month
Suppose you owe $15,000 at 18% APR and your required monthly payment is $450. Paying only $450 takes about 47 months and costs $5,950.86 in interest under this monthly model.
Add $100 each month, for a total payment of $550. The estimated payoff becomes 36 months, with $4,435.30 in interest and $19,435.30 paid in total.
That extra payment saves about 11 months and $1,515.56 in interest, assuming the rate and payment timing do not change.
Frequently Asked Questions
How do extra payments reduce debt payoff time?
After accrued interest is covered, the rest of each payment reduces principal. Adding a fixed extra amount reduces principal sooner, so later months usually accrue interest on a smaller balance and fewer payments are needed.
What if my payment is less than the monthly interest?
The balance would not decline under this model. The calculator returns a 0-month payoff rather than an infinite or misleading term. Increase the payment above the first month's estimated interest or verify your statement terms.
Does this work for credit cards?
It can provide a planning estimate for one fixed APR and fixed monthly payment. Many cards use daily average balances, changing minimum payments, multiple APR buckets, fees, and new transactions, so your issuer's statement will be more precise.
Will every lender apply my extra payment to principal?
Not always in the same way. Payments commonly cover fees and accrued interest before principal, and some servicers may advance the due date unless you give instructions. Check your agreement or servicer settings before relying on the estimate.
Educational estimate only. This model assumes one fixed-rate balance, monthly interest equal to APR divided by 12, payments made once per month, and no new purchases, fees, penalties, promotional rates, or payment-allocation rules. Many credit cards calculate interest daily, so statements and payoff quotes may differ. Verify how your lender or issuer applies extra payments and request an official payoff amount before the final payment. Projections longer than 1,200 months or payments that do not reduce principal return a zero payoff result.