Mortgage Amortization

Ever wonder how your mortgage goes from a pain in your neck to free and clear?

Well, it all has to do with a little thing called “amortization,” which is defined as the reduction of debt by regular payments of interest and principal sufficient to pay off a loan by maturity.

In simple terms, it’s the way your mortgage payments are distributed on a monthly basis, detailing how much interest and principal will be paid off each month for the duration of the loan term.

Understanding the way your mortgage amortizes is a great way to understand how different loan programs work. And an amortization calculator will show you how your balance is paid off on a monthly or yearly basis. It will also detail how much interest you’ll pay over the life of your loan, assuming you hold it to maturity.

Early Payments Go Toward Interest

amortization schedule

(pictured above is an actual “amortization schedule” from an active mortgage about five months into a 30-year mortgage)

During the first half of a 30-year fixed-rate loan, most of the monthly payment goes to paying down interest, with very little principal actually paid off. Towards the last 15 years of the loan you will begin to pay off a greater amount of principal, until the monthly payment is largely principal, and very little interest.

This is important to note because homeowners that continuously refinance will find themselves back in the interest-paying portion of the loan every time they start anew, meaning they’ll pay a lot more interest over the years. Each time you refinance, assuming you refinance into the same type of loan, you’re essentially extending the amortization period of the mortgage. And the longer the term, the more you’ll pay in interest.

Tip: If you have already paid down your mortgage for several years, but want to refinance to take advantage of low mortgage rates, consider refinancing to a shorter-term mortgage. This is one simple way to avoid “resetting the clock.”

Let’s look at a mortgage amortization example:

Loan amount: $100,000
Interest rate: 6.5%
Monthly mortgage payment: $632.07

Say you’ve got a $100,000 loan at 6.5% on a 30-year fixed payment. The monthly principal and interest payment is $632.07. If you break down the very first monthly mortgage payment, $541.67 goes toward interest and $90.40 goes toward principal. The total debt is reduced by $90.40, so next month you’ll only owe interest on $99,909.60.

So when it comes time to make your second monthly mortgage payment, interest is calculated on the new, lower balance. The payment would be the same, but $541.18 would go toward interest and $90.89 would go to principal. This interest reduction would continue until your monthly mortgage payments were going primarily to principal.

In fact, the 360th payment in our example contributes just $3.41 to interest and a whopping $628.66 to principal.

Consider Larger Mortgage Payments to Shorten Amortization Period

Okay, so now you have a better idea of how your mortgage amortizes. Your next move will be to determine if paying your mortgage down faster is a good idea.

In the example above, you’ll pay a total of $227,545.20 over the 30-year term, with $127,545.20 going toward interest.

If you make slightly larger payments, say $700 each month instead (consistently), your mortgage term will be cut by roughly seven years and you’ll only pay $76,448.10 in interest. That will save you about $50,000 over the life of the loan…not bad.

Take the time to look into biweekly mortgage payments as well. These are mortgage payments made every two weeks, which equates to 26 total payments a year, or 13 monthly mortgage payments. That extra month payment per year goes toward principal, lowering the total amount of interest paid and decreasing the term of the loan.

Every potential homeowner should take a look at an amortization schedule or a mortgage calculator to determine exactly how mortgage payments apply in their particular situation. Simply  knowing your interest rate is not enough to make an educated decision on a loan product.

And be sure you understand negative amortization as well, assuming if you got involved with a pesky option-arm loan.

Read more: 30-year vs. 15-year mortgages.


  1. Rosalie July 15, 2013 at 11:13 am -

    I don’t think people understand how important the amortization period is. They only seem to focus on monthly payments. But the interest savings on a 15-year mortgage are huge, assuming you can handle the extra cost each month.

  2. Colin Robertson July 15, 2013 at 1:02 pm -

    That’s true; most lenders just advertise the monthly payment amount, seeing that it’s what most borrowers focus on. And it’s true that a shorter-term loan will result in a lot less interest paid, but also consider most homeowners move in less than 10 years. And some invest their money elsewhere for larger returns. So the proposed amortization period doesn’t always come into play as scheduled.

  3. Ella July 16, 2013 at 9:38 pm -

    This is exactly why you should go with a 15-year fixed. You will pay A LOT less in interest over half the amount of time. Use an amortization schedule and you’ll see the many tens of thousands you will save.

  4. Patricia July 18, 2013 at 9:31 am -

    Most homeowners don’t know (or seem to care about) how a mortgage is actually paid off. They just look at the monthly payment and nothing else, thanks to the banks. It’s a shame because it could mean the difference of thousands of dollars.

  5. Thomas August 20, 2013 at 8:53 am -

    This is what they mean by resetting the clock if you refinance before your mortgage term is over. You essentially restart the amortization period, and again start paying nearly all interest in your early payments. So those that refinance should always consider shorter terms to avoid extra interest costs.

  6. Jack R. December 12, 2013 at 6:19 am -

    I know exactly how my mortgage is paid off, which is why I went with a 10-year fixed. I’ll save more than $100,000 in interest compared to a 30-year fixed and own my home 20 years sooner. Policymakers in Washington should abolish the 30-year fixed now! It’s a ripoff!

  7. Colin Robertson December 12, 2013 at 7:06 am -
  8. Quentin K. January 18, 2014 at 11:38 pm -

    If I make an extra mortgage payment, will that be reflected in the monthly payment of the amortization schedule? Or does it just reduce interest over the life of the loan?

  9. Colin Robertson January 20, 2014 at 11:12 am -

    If you were to make an extra payment, subsequent monthly payments would still be the same amount, but the interest portion of the payment would go down and the principal portion would go up. As a result, the term of your mortgage would be reduced.

  10. Margie B. July 31, 2014 at 5:31 pm -

    My husband would like to retire in 4 years when he’s 55, just in case his company lays him off, as it is happening to others there when they reach that age. We are 3 years into a 15 year loan at 3.125%. I’ve been putting extra (same amount as our mortgage amount) towards the principal each month.
    Question: Would it be more beneficial to put that amount each month towards the principal,or as an extra mortgage payment? Using amortization tables online, I’m seeing that we can pay off our home in 4 years by putting the extra towards the principal.
    What are your thoughts?

    Margie Bayer
    Auburn, WA

  11. Colin Robertson August 1, 2014 at 9:51 am -


    It sounds like you’re talking about two things that are essentially the same. Generally, any excess amount over your mortgage payment due each month goes toward the principal balance. Sometimes you have to indicate that the extra amount should go toward principal as opposed to say escrow. Either way, the quicker you apply extra (or larger) payments, the more beneficial it is. In other words, if you started making double payments the first month your mortgage was due, you’d save more (on interest) than if you didn’t start making double payments until say month 13 because each month a smaller balance would equate to less interest due the following month.

  12. Steve August 2, 2014 at 6:33 pm -

    Exactly, we are just now finding out that 16 years in, even when we double payments we missed the bigger boat during the first 15 years. We are aiming to get it fully paid in the next 3 years, but we already paid the majority of interest so the only good thing is time. Our next mortgage will be paid majority first 15 years instead to kill that extra interest.
    Nice blog appreciate it.

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