What is the biweekly mortgage calculator?
In short
A biweekly mortgage payment schedule cuts a 30-year mortgage to about 25–26 years and saves the typical homeowner $30,000–$50,000 in interest, with zero change to your budget other than payment timing.
This biweekly mortgage calculator shows how paying half of your monthly payment every two weeks accelerates your payoff. Because there are 52 weeks in a year, 26 half-payments equal 13 full monthly payments — one extra payment annually that goes straight to principal.
How to use this calculator
- 1Enter the home price and your down payment to set the loan amount.
- 2Enter your interest rate and the original loan term.
- 3Read your biweekly payment (half the monthly amount).
- 4Compare total interest and payoff time for monthly vs biweekly schedules.
- 5See exactly how much interest you save and how many months you cut.
The formula
- P
- — loan principal
- r
- — annual rate / 26 (biweekly rate)
- n
- — total biweekly periods
KalkWise simulates each biweekly period individually, applying interest at the biweekly rate and the rest of the payment to principal, until the balance reaches zero.
Worked example
The scenario
$320,000 loan at 6.5% on a 30-year term, paid biweekly instead of monthly.
The result
Biweekly payment ≈ $1,011 every two weeks vs $2,022/month. Payoff drops to about 25.5 years, saving roughly $45,000 in interest.
Common use cases
- Deciding whether to set up a biweekly payment plan with your lender
- Seeing the interest impact of one extra payment per year
- Comparing accelerated payoff strategies before committing
- Planning an earlier mortgage-free date without a big budget change
Limitations & assumptions
- Assumes a fixed interest rate — ARMs will behave differently after the fixed period.
- Some lenders hold biweekly payments and apply them monthly, which removes the benefit — confirm they apply payments as received.
- Does not include property tax, insurance, PMI, or HOA — only principal & interest.
Frequently asked questions
Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.