Mortgage Payoff Calculator

How it works

Evaluating an earlier mortgage payoff

Compare the baseline mortgage with the extra-payment scenario using the same starting balance and interest rate. Calendar-based extras let you represent payments when they occur, while the balance-inference option estimates a balance from the stated loan history. Review both the interest saved and the earlier payoff date. An inferred balance should be checked against a current lender statement before use.

Guides

• What your mortgage payment actually includes

  Understand principal, interest, ownership costs, and why a loan payment is different from a full housing budget.

Loan & schedule: formula and assumptions

Payment = P × r / [1−(1+r)^−n], where r is the monthly rate.

Equal monthly payments amortize a fixed-rate loan. Extra payments reduce principal after the regular payment.

Fixed-payment payoff: formula and assumptions

Payoff months = −ln(1−Pr/payment) / ln(1+r).

The monthly payment must exceed the interest due. The final installment is reduced to the remaining balance.

Inferred balance & calendar extras: formula and assumptions

Payment = principal / annuity present-value factor. Each month applies interest, scheduled payment, then extras.

Monthly, annual and dated one-time extras are combined. The final payment is capped at the debt owed. Compare the actual payoff and interest with an unchanged-payment baseline. Original-loan inference assumes all completed payments were contractual with no past extras. The known-payment mode infers principal from the entered remaining term.

Accelerated biweekly with balance inference: formula and assumptions

Accelerated installment = monthly payment / 2. Interest factor per interval = (1+APR/12)^(12/26).

This uses 26 equal interest periods per year. Current principal may be inferred from original terms or a payment/remaining-term pair. Loan-servicer collection and posting can differ.

Worked example

Reference example currency: USD. These fixed examples do not change with your calculator preferences.

Using the Loan & schedule example:

Loan amount ($)

250000

Annual interest rate (%)

6.5

Term (years)

30

Extra monthly payment ($)

0

First payment month

2026-11-01

Payment = P × r / [1−(1+r)^−n], where r is the monthly rate.

Example result

These are illustrative inputs. Change the values to explore a different scenario.

What to keep in mind

Assumes a fixed rate and no new borrowing or late fees.

Formula references

• CFPB: understanding mortgages (opens in a new tab)
• Investor.gov: financial tools and calculators (opens in a new tab)
• OpenStax loan amortization (opens in a new tab)
• CFPB mortgage terms: biweekly payments (opens in a new tab)

References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.

Common questions