It's SO easy, in fact, that people have made a business out of promoting this plan. If you didn't opt out of your lender's marketing list, you'll probably get a letter with your loan information, with interest savings in the tens of thousands of dollars, and an offer to let Biweekly Buddies Inc. to handle all of this for you.

Then you read on with your magnifying lens. A fee of several HUNDRED dollars after becomes payable to "The Buddies" (and non-refundable to you) after a few months of enrollment in the program. Then, there's a monthly service fee of a few dollars as long as your enrolled in the program. But hey, you're saving tens of thousands in interest, right?

(OK, I have a confession to make. The explanation I was going to give you originally involved going to Bret Whissel's Amortization Calculator, and going through a bunch of iterations with that tool to arrive at the answer. However, after chatting with my mother-in-law, who was a math teacher for 12 years, she suggested a MUCH easier way, and our answers agreed to within a dollar! So, I'm going to give you her method rather than mine. Thanks, Mom!)

Since the bi-weekly mortgage acceleration amounts to making an extra payment per year, spread out over the periodic payments, just take your principal plus interest payment, and divide it by 12. This is the extra amount that you apply to principal each month, which amounts to one extra payment per year. Q.E.D. One calculation. All done! Thanks, Mom! Not exactly the kinds of numerical cogitations that you want to spend two grand for, are they?

Now, one thing you may want to check is that you aren't charged lots of fees for changing how much you pay per month. We're not with our mortgage; you may not be with yours either.

Just kidding!

(Those payments go to my mother-in-law.)