Biweekly Mortgage Calculator
Paying half your mortgage every two weeks adds up to one extra payment a year. See how much time and interest that saves.
A worked example
Running this tool on current national benchmarks (Federal Reserve / Freddie Mac via FRED (St. Louis Fed)) — swap in your own numbers to see how the result moves.
- Loan amount
- $300,000
- Interest rate
- 6.50%
- Loan term (years)
- 30
paid off 5.8 years sooner
- Monthly payment$1,896.20
- Biweekly payment$948.10
- Biweekly payoff24.2 yrs
How the interest saved with biweekly payments changes with loan amount
Holding the other inputs at the example above, here is how the result moves as loan amount changes.
| Loan amount | Interest saved with biweekly payments | Monthly payment |
|---|---|---|
| $200,000 | $58,748 | $1,264.14 |
| $300,000 | $88,122 | $1,896.20 |
| $450,000 | $132,183 | $2,844.31 |
| $600,000 | $176,244 | $3,792.41 |
The math behind it
The calculator first finds your normal monthly payment, then splits it in half and applies that half every two weeks. Because there are 52 weeks in a year, you make 26 half-payments — the equivalent of 13 monthly payments instead of 12. That one extra payment a year goes straight to principal, so it accelerates payoff. The calculator compares the biweekly payoff time and total interest against the standard monthly schedule.
Assumptions & limits
- Interest accrues on the biweekly schedule at the annual rate divided by 26. The saving comes from paying the equivalent of one extra monthly payment each year.
- The rate is fixed for the whole term. Payments are principal and interest only — taxes and insurance are excluded.
- The plan assumes every half-payment is applied to your balance as it arrives, which is what produces the interest savings.
- No enrollment or service fees are modeled. Some third-party biweekly programs charge fees that eat into the benefit.
Source: Freddie Mac PMMS via FRED. Annual averages; latest weekly reading shown.
Common questions
How does paying biweekly save so much interest?
Twenty-six half-payments a year add up to 13 full payments instead of 12. That extra payment goes entirely to principal, shrinking your balance faster and cutting the interest charged on it every month thereafter. Over a full term the compounding effect can save years and a substantial sum.
Can I just make one extra payment a year instead?
Yes — mathematically, adding one-twelfth of your payment to each monthly bill, or making a single extra payment yearly, achieves nearly the same result without a formal biweekly plan. The biweekly schedule mainly enforces the discipline automatically.
Will my lender apply biweekly payments correctly?
Not always. Some servicers hold each half-payment until the second arrives, then apply a full monthly payment, which erases the benefit. Confirm your servicer credits payments immediately, or set up your own extra-principal payment instead.