This New Jersey biweekly mortgage calculator shows how paying half your monthly mortgage every two weeks shortens your New Jersey loan and how much interest you save — using full period-by-period amortization, not a rule of thumb.
How it works
The tool first computes your scheduled monthly principal-and-interest payment with the standard amortization formula:
M = P * r * (1 + r)^n / ((1 + r)^n - 1)where P is the loan, r is the monthly rate (annual / 12), and n is the number of months. It then runs two amortization schedules:
- Monthly — the scheduled payment once a month (12 payments a year).
- Biweekly — half the monthly payment every two weeks. There are 26 two-week periods in a year, so you make 26 half-payments = 13 full monthly payments a year. Each biweekly period accrues interest at the annual rate divided by 26.
That single extra payment each year goes entirely to principal, so the biweekly schedule clears the balance sooner. The difference in months and in total interest paid is your time saved and interest saved.
Example
A $320,000 New Jersey mortgage at 6.5% over 30 years has a scheduled payment of about $2,023/month and would cost roughly $408,142 in total interest over the full 30 years.
Switch to biweekly half-payments of about $1,011 every two weeks and the loan pays off in about 24 years 2 months instead of 30 years — cutting off roughly 5 years 10 months and saving about $93,997 in interest.
Notes
This is an estimate only and not financial advice. It assumes a fixed interest rate, that every biweekly payment is applied to principal as soon as it is received, and that there are exactly 26 biweekly periods a year. Property tax, insurance, and escrow are excluded. Many servicers charge a setup fee for true biweekly plans or hold payments until a full month is collected — confirm with your New Jersey lender, and remember you can usually get the same result for free by adding one-twelfth of your payment to monthly principal.