Biweekly Mortgage Payment Savings Calculator

Inputs Validated

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Amortization Runs

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Savings Check

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Output Rendered

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Mortgage Inputs

Fixed-rate loan assumed. Payoff dates are estimated from today's date.

Loan Amount ($) Original principal balance. Annual Rate (%) Fixed APR, e.g. 6.0. Term (years) 1–50 years. Extra Annual Payment ($) Optional lump sum toward principal each year.

Monthly PlanBaseline

Standard monthly payments

Payment—

Months to Payoff—

Payoff Date—

Total Interest—

Interest Saved—

Time Saved—

One payment each month; interest accrues at the annual rate ÷ 12. This is the reference case every plan is measured against.

Biweekly Borrower-arranged

DIY 26-half-payment split

Payment—

Months to Payoff—

Payoff Date—

Total Interest—

Interest Saved—

Time Saved—

You, not the lender, split your monthly payment in half and pay every two weeks: 26 half-payments — the equivalent of 13 full payments — per year. The loan contract is unchanged, so interest still accrues at your monthly rate; the extra month of principal per year is what accelerates payoff.

Biweekly Lender-adopted

Lender biweekly program

Payment—

Months to Payoff—

Payoff Date—

Total Interest—

Interest Saved—

Time Saved—

The lender re-amortizes the loan on a biweekly schedule: half your monthly payment is drafted every 14 days and interest accrues biweekly at the annual rate ÷ 26. Same dollars as the DIY plan but a slightly different accrual path. Lender programs frequently charge enrollment fees, which are not modeled here.

Model assumptions

Fixed-rate amortization. The monthly baseline and the borrower-arranged plan accrue interest monthly at the annual rate ÷ 12; the borrower-arranged plan is modeled as the equivalent of 13 full monthly payments per year (26 half-payments of half your monthly payment).
The lender-adopted plan accrues interest per biweekly period at the annual rate ÷ 26, with half your monthly payment applied every 14 days (26 payments per year).
An extra annual payment is added to principal and spread evenly across every plan (annual extra ÷ 12 per month, or ÷ 26 per biweekly period).
Payoff dates are estimates anchored to today's calendar date and the final payment is rounded to a whole payment schedule.
Not modeled: escrow, taxes, insurance, PMI, rounding of real payments, prepayment penalties, or lender-program enrollment fees. Not financial advice.