Debt calculator
Debt Payoff Calculator
Estimate how long one debt may take to repay, its payoff date and total interest, and the time and interest an extra monthly payment could save.
September 2026
Enter your details
Results update privately in your browser.
Understand the estimate
What your result means
The payoff timeline and total interest describe the scenario using your current monthly payment plus the optional extra amount. The approximate payoff month and year are calculated from the current date and the estimated number of payments; they are not a lender-confirmed due date.
The comparison holds the balance and APR constant: current monthly payment versus current monthly payment plus the additional monthly amount. Subtracting the accelerated scenario’s months and interest from the base scenario gives months saved and interest saved. With no extra payment, savings are zero; at zero APR there is no interest to save.
Before you enter a value
What should I enter?
- Starting balance and interest rate
- Enter the balance and annual rate for the debt you are modeling.
- Base payment
- Enter the payment you expect to make every month before any additional amount.
- Extra payment
- Enter an additional recurring amount to compare with the base-payment scenario. Confirm how a lender applies extra payments.
Worked example
Example: a $100 monthly extra payment
Inputs
- Starting balance: $12,000
- APR: 18%
- Base payment: $350 per month
- Extra payment: $100 per month
Results
- Base payment only: about 49 months and $4,977 total interest
- With $100 extra: about 35 months and $3,440 total interest
- The calculator estimates 14 months and about $1,536 in interest difference
The comparison holds the balance, APR, and base payment constant. It does not model fees, changing rates, or lender-specific payment allocation.
Important considerations
Before you decide
- Making a payment that barely exceeds interest and expecting rapid principal reduction.
- Assuming an extra payment is always applied as intended without checking loan terms.
- Treating interest savings as the only financial consideration.
How we calculate
A transparent estimate you can inspect.
Formula
Each month, interest is calculated on the remaining balance using APR divided by 12, then the entered payment is applied. The final payment may be smaller. The model compares a fixed base payment with that payment plus a fixed extra monthly amount, assuming a fixed APR. Fees, changing rates, and lender-specific payment allocation are excluded.
Privacy
Your values are calculated locally and are not sent to a server by this calculator.
Use with care
Results are for informational purposes, not financial, tax, legal, lending, or investment advice.
Understanding your results
Payoff duration and interest are simulated month by month, including a partial final payment.
Assumptions and limitations
- Assumes a fixed APR and fixed monthly payments.
Common questions
Before you decide
How long will it take to pay off my debt?
Enter your current balance, APR, monthly payment, and optional additional payment. The calculator estimates how many monthly payments are needed, the total interest, and an approximate payoff month and year under those fixed assumptions.
Why does it say Payment is too low?
This comparison currently requires both the base payment and the base-plus-extra payment to repay the balance. If the base payment does not exceed monthly interest, it returns this message even when the extra payment could make repayment possible. Very long scenarios beyond the model’s calculation limit can also be unavailable.
How much can an extra payment shorten payoff?
This calculator estimates the difference between the base payment and the base payment plus your extra amount.
Does paying extra reduce interest?
With a fixed balance and rate, reducing the modeled balance sooner can reduce future interest. Confirm lender payment application rules.
Should I apply extra payments to principal?
Check the lender or servicer instructions and your loan terms. This calculator does not provide individualized advice.