Biweekly Mortgage Savings Calculator
Calculate interest savings and years saved by switching from monthly to biweekly mortgage payments.
Shows total interest saved and payoff date.
Biweekly mortgage payments work by splitting your standard monthly payment in half and paying that amount every two weeks instead of once a month. The financial power comes from a simple calendar fact: there are 26 biweekly periods in a year, which equals 13 full monthly payments — one extra payment per year applied entirely to principal.
Standard monthly payment formula: M = P × [r(1+r)^n] ÷ [(1+r)^n − 1]
Where:
- M = monthly payment amount
- P = principal (loan amount)
- r = monthly interest rate = annual rate ÷ 12
- n = total number of monthly payments (years × 12)
Biweekly payment: Biweekly Amount = M ÷ 2
Annual extra payment: Extra Principal/Year = M × 1 (one full extra monthly payment)
Interest saved (approximate): Interest Saved ≈ Extra Annual Payment × Remaining Years × (1 + r/2)
The exact savings require amortization modeling — the calculator simulates each payment period to compute precise interest saved and months removed.
What each variable means:
- Principal — the original loan amount, or current outstanding balance
- Annual Interest Rate — your mortgage’s stated rate (not APR, which includes fees)
- Loan Term — typically 15 or 30 years; the calculator models full or remaining term
- Extra payment impact — the extra annual payment reduces the balance earlier, meaning subsequent interest charges are calculated on a lower base
Reference: typical savings on a 30-year mortgage at 7%
- $200,000 loan: saves ~$34,000 in interest, pays off ~4 years early
- $350,000 loan: saves ~$60,000 in interest, pays off ~4.5 years early
- $500,000 loan: saves ~$85,000 in interest, pays off ~5 years early
Worked example: Loan: $350,000. Rate: 6.5%. Term: 30 years.
Monthly payment = $350,000 × [0.005417 × (1.005417)^360] ÷ [(1.005417)^360 − 1] = $2,212/month
Biweekly payment = $2,212 ÷ 2 = $1,106 every two weeks
Extra annual payment = $2,212 (one full extra payment) Estimated interest saved ≈ $56,000–$62,000 over the life of the loan Loan paid off approximately 4.5 years early — at year 25.5 instead of year 30.