Biweekly Mortgage Payment Calculator

A year has 52 weeks, so "half the payment every two weeks" means 26 half-payments — 13 full payments where a monthly schedule makes 12. The 13th payment isn't magic; it's simply one extra full payment a year, and because your regular payments already cover the interest due, that extra money goes entirely to principal. A smaller principal accrues less interest every month after, so a bigger slice of each regular payment starts hitting principal too — the same reverse-amortization snowball an extra monthly payment starts, just funded by the calendar instead of your budget.

Watch one distinction: paying twice a month (on the 1st and 15th, say) is 24 half-payments — exactly 12 full payments, which saves nothing. The savings live entirely in the two extra half-payments that "every two weeks" produces.

Take the defaults above: a $300,000 balance at 6.5% with 30 years remaining. The monthly payment is about $1,896.20, so biweekly you'd pay $948.10 every two weeks. On the monthly schedule the loan runs the full 30 years and costs about $382,633 in interest. Paid biweekly, it clears in about 24 years 2 months with about $294,512 in interest — the loan ends 5 years 10 months sooner and saves roughly $88,122. The chart shows the two balance curves pulling apart a little more every year.

That's a good trade for money you were going to pay anyway — but it is still an estimate. It assumes a fixed rate and, importantly, that every half-payment is credited to the loan the day it arrives. A servicer that holds your half-payment until the month's second half shows up saves you slightly less than this page shows.

Two honest warnings before you enroll in anything. First, the savings only exist if the extra money is applied to principal. Some servicers hold partial payments in suspense until a full payment accumulates, and some treat extra money as "next month's payment" — which saves you nothing. Confirm, in writing or in the payment form's own checkbox, that the 13th payment hits principal.

Second, some lender and third-party biweekly programs charge for this — setup fees, sometimes a fee per debit — for arithmetic you can do yourself at no cost. The CFPB's Ask CFPB library covers what to check before signing up for a payment program. The free do-it-yourself version: divide your monthly payment by 12 and pay that as an extra principal payment each month. On the example above that's about $158 a month extra, which lands within about $900 of the biweekly result — the small gap is only because biweekly money arrives a little earlier in the month. The extra mortgage payment calculator runs exactly that plan on your numbers, and it works even if your paychecks aren't on a two-week rhythm.

Is biweekly the same as paying twice a month? No, and the difference is the whole trick. Twice a month (semi-monthly) is 24 half-payments a year — exactly 12 full payments, nothing extra. Every two weeks is 26 half-payments, because 52 weeks divide into 26 fortnights — 13 full payments, and the 13th is where every dollar of the savings comes from.

Do I need my lender's biweekly program to get these savings? No. Paying one-twelfth of your monthly payment as an extra principal payment each month gets you within about 1% of the same savings — free, with no enrollment and no fees. The extra mortgage payment calculator runs that version on your numbers.

Does paying biweekly lower my required monthly payment? No. The required payment stays the same — the extra half-payments shorten the end of the loan rather than shrinking the monthly bill. (A recast or refinance is what lowers the payment.)

This is an estimate assuming a fixed interest rate, no fees, and every half-payment credited when it arrives. Confirm with your servicer that extra amounts apply to principal, not next month's payment, before relying on this.