# Biweekly Payments — $300k at 6% — Mortgage Payoff Calculator

> Switching to biweekly payments on a $300k 30-year mortgage at 6% saves $73,665 in interest and pays it off 5 years 5 months early — with no budget increase.

- **Answer:** Save ~$73,665 in interest
- **Category:** Finance & Money
- **Interactive calculator:** https://youcalc.com/en/finance-money/mortgage-payoff/biweekly-300k-6pct/
- **Price:** Free, no sign-up required
- **Full calculator:** [Mortgage Payoff Calculator](https://youcalc.com/en/finance-money/mortgage-payoff/)
- **Pre-filled inputs:** `m=known-term&p=300000&r=6&t=30&ry=30&rm=0&pk=biweekly&c=USD`

| Metric | Value |
| --- | --- |
| Interest saved | $73,665 |
| Time saved | 5 yr 5 mo |
| New payoff term | 24 yr 7 mo |
| Effective monthly payment | $1,949 |
| Original monthly payment | $1,799 |


## Overview

The biweekly trick works because paying half your monthly amount every two weeks adds one extra full payment per year (26 half-payments = 13 monthly payments instead of 12). On a $300,000 mortgage at 6%, this free restructuring saves $73,665 in interest and retires the loan in 24 years 7 months. Your effective monthly outlay rises by only $150 ($1,949 vs. $1,799), yet you save nearly as much as the $100/month extra-payment scenario ($73,665 vs. $53,347).

## Method

The calculation uses standard mortgage amortisation. The scheduled monthly payment is derived from the level-payment formula: P × r(1+r)^n / ((1+r)^n − 1), where P is the original principal, r the monthly interest rate (annual rate divided by 12), and n the total number of payments. From there, the calculator runs a month-by-month simulation: each period it applies the monthly rate to the current balance to find the interest charge, subtracts that from the payment (base plus any extra) to find the principal reduction, and carries the lower balance into the next period. Extra payments are added to the principal portion only, directly reducing the outstanding balance. The simulation stops when the balance reaches zero, and the total months elapsed becomes the new payoff term. Savings in interest and months are the difference between the no-extra simulation and the with-extra simulation, measured from the current period forward. The finance utilities supply the level-payment and balance-after-k-payments helpers used in the preliminary setup step.

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## Sources

- https://www.investopedia.com/mortgage-calculator-5096931
- https://www.calculator.net/mortgage-payoff-calculator.html

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Interactive version: https://youcalc.com/en/finance-money/mortgage-payoff/biweekly-300k-6pct/ · From YouCalc — https://youcalc.com