Mortgage Calculator Guide: Extra Payments, Bi-Weekly Schedules and Amortization

A mortgage is probably the biggest loan you'll ever take on, and small changes to how you pay it can save tens of thousands of dollars. Calc Pro's Mortgage worksheet shows you exactly how much, whether you add a little extra each month or switch to an accelerated bi-weekly schedule.

Opening the Mortgage Worksheet

Try it free in your browser: Mortgage Calculator

1. Open the Financial calculator from the side menu
2. Tap Mortgage in the list of worksheets

The Mortgage worksheet is included free in the iPhone and iPad app.

The Fields

Field	What to enter
Principal	The price of the home, or the amount you're borrowing
Down Payment	What you're paying up front
Interest Rate	The annual rate, e.g. 6.5 for 6.5%
Term (Years)	The length of the mortgage
Other Fees	Any fees added to the loan
Extra Payment	Extra principal you'll pay with each payment

Calc Pro then shows your Payment, Total Interest, Total Repaid, and, when you add an extra payment, the Interest Saved and Months Saved.

Example 1: A Standard Mortgage

A $400,000 mortgage at 6.5% over 30 years, paid monthly:

• Payment: $2,528.27 a month
• Total Interest: $510,177.95
• Total Repaid: $910,177.95

Over 30 years you'd pay more in interest than the home cost.

Example 2: Add $200 a Month

Enter 200 in Extra Payment:

• Total Interest: $398,286.42
• Interest Saved: $111,891.54
• Months Saved: 67, so the mortgage is paid off about five and a half years early

An extra $200 a month saves more than $110,000.

Example 3: Accelerated Bi-Weekly Payments

Choose your payment schedule in Options → Financial → Payment schedule (Mortgage):

• Monthly, semi-monthly, bi-weekly, weekly or bi-monthly
• Each also has an accelerated version

The accelerated schedules are the ones that save money. Bi-Weekly Accel pays half your monthly payment every two weeks. That's 26 half-payments a year, or 13 full monthly payments instead of 12, so the extra payment goes straight to principal.

Same $400,000 mortgage at 6.5% over 30 years:

Schedule	Payment	Total Interest	Paid off in
Monthly	$2,528.27	$510,177.95	30 years
Bi-Weekly	$1,166.34	$509,749.06	30 years
Bi-Weekly Accelerated	$1,264.14	$392,682.25	about 24 years
Weekly Accelerated	$632.07	$392,187.75	about 24 years

Plain bi-weekly barely changes anything, because it spreads the same yearly amount over more payments. Accelerated bi-weekly saves about $117,500 in interest.

Amortization Schedules

Tap View Amortization Schedule to see every payment, split into principal and interest, along with the balance remaining. In the iPhone and iPad app this is a Pro Premium feature.

Early payments are mostly interest. For the $400,000 mortgage above:

Payment	Principal	Interest	Balance
1	$362	$2,167	$399,638
180	$951	$1,577	$290,237
360	$2,515	$14	$0

Halfway through the mortgage, you still owe almost three quarters of the loan. That's why extra payments made early save the most.

Tips

1. Check your lender's schedule. Some lenders offer accelerated bi-weekly payments; others need you to ask.
2. Extra payments work best early. A dollar of extra principal in year one saves far more interest than a dollar in year twenty.
3. Compare, don't guess. Try a few extra-payment amounts and watch Interest Saved to find what's worth it for you.
4. Share the numbers. With Pro Premium, save or e-mail the worksheet as a PDF to talk it through with your lender or partner.

For every other worksheet, see the Financial Calculator guide.

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