# Mortgage Payoff Calculator

> See how extra monthly payments or a one-off lump sum shorten your mortgage, when it will be paid off and how much interest you save.

Category: Finance · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/mortgage-payoff-calculator

Every extra payment goes straight to the balance, so less interest accrues from then on. Enter what you still owe and what extra you can pay to see the new payoff date and the interest saved.

Also called: Mortgage overpayment calculator, Early mortgage payoff calculator.

## Inputs
- Remaining balance (default 200000)
- Interest rate (per year) (unit %; default 6)
- Time left: years (unit years; default 30)
- Time left: extra months (unit months; default 0; optional)
- Extra payment each month (default 200; optional)
- One-off payment now (default 0; optional)
- Currency

## Results
- Interest saved
- New time to pay off
- Months saved
- Payments left
- Regular monthly payment (principal and interest)
- Interest on current plan
- Interest with extra payments

## Formula

```
Regular payment P = B·i(1+i)^n ÷ ((1+i)^n − 1);  months to pay off with extra E: N = −ln(1 − B·i ÷ (P + E)) ÷ ln(1 + i), rounded up;  Interest saved = interest on current plan − interest with extra payments
```

Where:
- B: remaining balance (after any lump sum for the new plan)
- i: monthly rate = annual rate ÷ 12
- n: months left on the current plan
- E: extra monthly payment

## Worked example
1. Regular payment on 200,000 at 0.5% a month over 360 months = $1,199.10; interest over the term = 1,199.101 × 360 − 200,000 = $231,676.38.
2. Paying 1,399.10: N = −ln(1 − 200,000 × 0.005 ÷ 1,399.10) ÷ ln(1.005) = 251.5, so 252 payments (21 years).
3. Interest falls to $151,875.87, a saving of $79,800.51 and 108 months.

**Result:** Adding $200 a month to a $200,000, 6%, 30-year mortgage pays it off 9 years early and saves about $79,800 in interest.

## What the result means

Extra payments save the most when made early, because they remove balance that would otherwise accrue interest for decades. Compare the saving with what the money could earn elsewhere, and keep an emergency fund first.

## Assumptions and limits
- The interest rate is fixed and interest is charged monthly on the outstanding balance.
- The regular payment is the one that clears the balance over the time left; taxes and insurance are excluded.
- All extra money reduces the principal immediately.
- Some lenders charge early repayment fees or limit overpayments; check your mortgage terms.
- Adjustable-rate mortgages need a different calculation.

## Questions

### Is a lump sum or a monthly extra better?

Money paid earlier saves more interest. A lump sum today beats the same total spread over later months.

### Will my monthly payment go down?

Usually not: the payment stays the same and the loan ends sooner. Some lenders can recast the loan to lower the payment instead.

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_This calculator gives estimates for planning. It is not financial advice, and lenders’ actual terms, fees and rounding may differ._

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/mortgage-payoff-calculator