Mortgage Payoff Calculator
A mortgage payoff calculator answers a question every homeowner eventually asks: at my current payment, how long until the loan is gone? Enter your remaining balance, the interest rate and the monthly payment you make, and this tool returns the number of months to payoff, that span expressed in years and months, and the interest you will still pay between now and the final installment. It uses the standard payoff formula, which inverts the loan amortization equation to solve for the number of months. Because interest is charged on the balance, paying more each month clears the balance faster and cuts the interest in every later month, so even small changes to the payment can move the payoff date by years. Try raising the monthly payment to see the effect. The calculator also checks a key limit: if the payment is no larger than the first month of interest, the loan can never be paid off, and it tells you so rather than returning a misleading figure. The figures here cover principal and interest only and exclude taxes and insurance, which the US Consumer Financial Protection Bureau recommends budgeting separately. Every result is computed deterministically from the formula below, with a worked example that reconciles exactly to the calculator.
Months to payoff is n = -ln(1 - rB/M) / ln(1+r). A $300,000 balance at 6.5% paid at $1,896.20 a month clears in 360 months (30 years).
Mortgage payoff formula
n = -ln(1 - r * B / M) / ln(1 + r)
n = number of months to payoff
B = current balance
M = monthly payment (principal and interest)
r = monthly interest rate = annual rate / 100 / 12
Requires M > B * r, otherwise the loan never amortizes
The formula rearranges the loan equation to solve for the number of months. If the monthly payment M is not greater than the first month of interest (B times r), the balance never falls and there is no payoff date. Total interest remaining is M times n minus the balance.
Worked example
A balance of 300,000 at 6.5% with a monthly payment of 1,896.20. First the monthly rate: r = 0.065 / 12 = 0.00541667.
- r * B / M = 0.00541667 * 300,000 / 1,896.20 = 0.856977
- 1 - r * B / M = 1 - 0.856977 = 0.143023
- n = -ln(0.143023) / ln(1.00541667) = 1.944750 / 0.005402 = 360 months
- Time to payoff = 360 / 12 = 30 years and 0 months
- Total interest remaining = 1,896.20 * 360 - 300,000 = 382,632.00
The loan is paid off in 360 months, which is 30 years and 0 months, with 382,632.00 of interest still to pay. These are the calculator's default inputs, so the results above match the widget exactly.
How the payment changes the payoff (balance 300,000 at 6.5%)
A higher monthly payment clears the balance sooner. These rows use the payoff formula above for a 300,000 balance at 6.5%.
| Monthly payment | Months to payoff | Years |
|---|---|---|
| 1,896.20 | 360 | 30.0 |
| 2,096.20 | 276 | 23.0 |
| 2,396.20 | 210 | 17.5 |
| 2,896.20 | 152 | 12.7 |
| 3,896.20 | 100 | 8.3 |
Months rounded to a whole month. Method: US Consumer Financial Protection Bureau, Owning a Home.
Mortgage payoff calculator: frequently asked questions
How do I work out months to pay off a mortgage?
Use the formula n = -ln(1 - r times B divided by M) divided by ln(1 + r), where B is the current balance, M is the monthly payment and r is the monthly interest rate (annual rate divided by 12). The result is the number of months until the balance reaches zero. This calculator applies that formula and rounds to a whole month, so you can see how long the remaining loan will take to clear.
What if my payment is too small to ever pay off the loan?
If the monthly payment is no larger than the interest charged on the balance in the first month (balance times the monthly rate), the loan never amortizes: the payment does not even cover interest, so the balance never falls. The calculator checks for this and tells you the payment must exceed the monthly interest before a payoff date can be found. Raising the payment fixes it.
Does a bigger monthly payment really save that much interest?
Yes. Because interest is charged on the balance, paying the balance down faster cuts the interest in every later month. Even a modest increase in the monthly payment can shorten the term by years and save a large amount of total interest. Enter a higher payment in the calculator to see the new payoff date and the lower remaining interest.
Is the interest remaining the same as total interest paid?
Remaining interest is the interest you will still pay from today until payoff, based on your current balance and payment. It is the total of future payments minus the current balance. It is not the interest already paid on the loan so far, and it is not the original total interest from when the loan started. It looks forward from where the balance is now.
Why round the months up to a whole month?
Mortgages are paid in whole monthly installments, so a fractional result such as 287.4 months means the loan is cleared during the 288th payment, with a slightly smaller final payment. Reporting a whole number of months reflects how repayment actually works. The remaining interest shown uses the whole-month payoff so the figures stay consistent with a real payment schedule.
Official sources
- Mortgage basics, paying off a loan early and the costs of owning a home: US Consumer Financial Protection Bureau, Owning a Home. As at 24 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 24 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.