# Mortgage Amortization Calculator

> See a year-by-year mortgage amortization schedule and how extra monthly or one-off payments cut the interest you pay and the time until the loan is gone.

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

Every extra payment goes straight to principal, so it removes all the future interest on that amount. This schedule compares your mortgage with and without extra payments.

Also called: Mortgage payoff calculator, Extra payment calculator.

## Inputs
- Mortgage amount (default 300000)
- Interest rate (per year) (unit %; default 6.5)
- Term (unit years; default 30)
- Extra payment every month (default 200; optional)
- One-off extra payment (default 0; optional)
- Paid in month number (default 12; optional)
- Currency

## Results
- Interest saved
- Regular monthly payment
- Total interest with extra payments
- Months to pay off
- Months saved
- Total paid

## Formula

```
Payment A = L × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1). Each month: interest = balance × r; balance = balance + interest − A − extra.
```

Where:
- L: mortgage amount
- r: annual rate ÷ 12 ÷ 100
- n: term in months
- extra: extra principal paid that month

## Worked example
1. Regular payment on $300,000 at 6.5% over 360 months = $1,896.20; interest over the full term = $382,633.47.
2. Paying $200 extra each month, the balance reaches zero after 277 payments.
3. Interest falls to $279,184.67, a saving of $103,448.79, and the loan ends 83 months (almost 7 years) early.

**Result:** An extra $200 a month on a $300,000, 6.5% mortgage saves about $103,000 of interest and clears it nearly 7 years early.

## What the result means

Extra payments made early in the loan save the most, because they remove interest for the longest time. Check that your lender applies extra payments to principal and does not charge prepayment penalties.

## Assumptions and limits
- Fixed rate; the regular payment stays the same and extra payments shorten the term.
- Extra payments are applied to principal in the month they are made.
- Prepayment limits or penalties, taxes and insurance are not modelled.

## Questions

### Is it better to pay extra or invest?

Paying extra earns a guaranteed return equal to your mortgage rate. Investing may earn more or less; compare after tax and risk.

### How is this different from the loan amortization calculator?

This page models extra monthly and one-off payments and summarises the schedule by year; the loan amortization calculator shows a plain month-by-month schedule.

## Related calculators
- [Loan Amortization Calculator](https://calculators.geekmidst.com/calculators/loan-amortization-calculator)
- [Mortgage Calculator](https://calculators.geekmidst.com/calculators/mortgage-calculator)
- [UK Mortgage Calculator](https://calculators.geekmidst.com/calculators/mortgage-calculator-uk)
- [Canadian Mortgage Calculator](https://calculators.geekmidst.com/calculators/canadian-mortgage-calculator)

_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-amortization-calculator