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Biweekly Payment Calculator

A biweekly payment calculator splits your monthly payment in half and pays it every two weeks. That produces 26 half-payments a year, which shortens the term and reduces the total interest.

By the Loansloth Editorial Team · Last updated 2026-09-16

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How this calculator works

Biweekly payments split the monthly payment in half and pay it every two weeks. Because a year has 26 two-week periods, you make 26 half-payments, the equivalent of 13 monthly payments instead of 12.

Monthly payment: M = P * r * (1 + r)^n / ((1 + r)^n - 1).

Biweekly payment = M / 2. Using the biweekly rate r = annual rate / 26 / 100, the number of biweekly periods is:

N = -ln(1 - r * P / (M / 2)) / ln(1 + r).

The extra payment each year shortens the term and reduces total interest. If the half-payment cannot cover the biweekly interest, the balance never falls.

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Frequently asked questions

Why do biweekly payments save interest?
You make 26 half-payments a year, which equals 13 full monthly payments. The extra payment reduces principal faster, so less interest accrues.
Do all lenders accept biweekly payments?
No. Some lenders support them, and some third parties charge a fee. Ask your lender how it handles partial or biweekly payments before enrolling.
What if my lender charges a fee for biweekly payments?
Compare the fee with the interest you save. If the fee is larger than the savings, paying extra toward principal directly may be cheaper.
Does the calculator assume payments start today?
It estimates the number of biweekly periods from the current balance. The actual calendar date depends on when your first payment is made.

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