Biweekly vs Monthly Mortgage Payment Calculator
Compare biweekly and monthly mortgage payments.
Biweekly pays one extra month per year — calculate years and interest saved over a 30-year loan.
Biweekly schedules pay 13 monthly equivalents per year, not 12. That is the entire trick. There are 52 weeks in a year, so 26 biweekly half-payments equal 13 full monthly payments. The 13th payment goes straight to principal. Compounded over 25-30 years, that one extra payment per year cuts 5-7 years off a 30-year loan.
Two ways your bank might do this.
- True biweekly: payments deducted every two weeks, applied to principal as soon as they hit. Extra principal credit happens twice a year (when 3 payments fall in a month).
- Pseudo-biweekly: bank holds the half-payment until the full monthly is due, then applies it. No interest savings — the bank just collects float.
Most mortgage servicers offer the second flavor and charge a $5-10 monthly “biweekly enrollment fee.” Avoid that. If you want the savings, just send 1/12 of one extra monthly payment with each regular monthly payment, or send a 13th full payment in December. Same effect, no enrollment cost, no float for the bank.
The math actually paid. On a $300,000 loan at 6.5% / 30 years:
- Standard monthly P&I: $1,896
- Total interest paid: $382,633
- Biweekly equivalent: 26 × $948 = $24,648/year (one extra monthly’s worth)
- Biweekly total interest: $295,200
- Years to payoff: about 25 years (60 months early)
- Interest saved: ~$87,000
Why it works so well. Mortgage interest is front-loaded. The first year of payments on a 30-year is mostly interest. Killing principal early dodges the most interest you would otherwise pay. A dollar of extra principal in year 1 is worth far more than a dollar in year 25.
The trap. Biweekly only beats monthly if you actually have the cash flow to make 13 payments of money. If you are stretched and switch to biweekly, the next time something breaks you are forced to skip — wiping out the savings. Build the emergency fund first, then accelerate the mortgage.
Comparison to lump-sum prepayment. A single $20,000 prepayment in year 5 saves slightly more interest than 5 years of biweekly. Both work; pick whichever fits how you actually save money.