Mortgage Refinancing Math
Mortgage Basics
What Is a Mortgage?
A mortgage is a loan used to buy a home. It's that simple. Since most people don't have enough cash to buy a property outright, they borrow money from a lender, like a bank. In return, the borrower agrees to pay back the loan, plus interest, over a set period of time. The home itself acts as collateral, which means if the borrower stops making payments, the lender can take possession of the property.
Mortgage
noun
A loan agreement where a borrower receives money to purchase real estate and repays the lender over time. The property serves as security for the loan.
The Parts of a Payment
Your monthly mortgage payment is more than just a piece of the loan. It's typically made up of four parts, often shortened to PITI.
PITI stands for Principal, Interest, Taxes, and Insurance. These are the four components of most monthly mortgage payments.
Principal is the amount of money you borrowed. Each payment you make reduces this balance.
Interest is the cost of borrowing the money, expressed as a percentage of the principal. Lenders charge interest to make a profit on the loan.
Taxes refers to property taxes. Lenders often collect these with your mortgage payment and hold them in an account called an escrow account. They then pay the tax bill on your behalf when it's due.
Insurance is homeowners insurance, which protects your property against damage from things like fires or storms. Like taxes, these premiums are usually collected monthly and paid from your escrow account.
How You Pay It Back
When you get a mortgage, your lender gives you an amortization schedule. This is a table that details each payment over the life of the loan. It shows how much of each payment goes toward principal and how much goes toward interest.
At the beginning of your loan, a large portion of your payment goes to interest. As time goes on, the balance shifts. More and more of your payment goes toward paying down the principal until the loan is fully paid off.
Mortgages come in two main flavors based on how interest is calculated.
| Mortgage Type | How It Works | Best For... |
|---|---|---|
| Fixed-Rate | The interest rate stays the same for the entire loan term. Your monthly principal and interest payment never changes. | Borrowers who plan to stay in their home for a long time and prefer predictable payments. |
| Adjustable-Rate (ARM) | The interest rate is fixed for an initial period, then changes periodically based on market rates. | Borrowers who don't plan to stay in their home long-term or expect their income to rise. |
Getting a Mortgage
Securing a mortgage involves several steps. It starts with getting your finances in order, checking your credit, and saving for a down payment.
The formal process begins with an application. You'll need to provide detailed information about your income, assets, and debts.
A crucial early step is pre-approval. This is when a lender reviews your financial situation and tells you how much they're willing to lend you. It shows sellers you're a serious buyer.
Getting preapproved for a mortgage is an important step in the homebuying process: It gives you a solid idea of how much you can borrow, and it shows sellers that you’re serious about buying a home.
After you submit your application, it goes into underwriting. This is where the lender verifies all your information to make a final decision. If approved, the final step is closing, where you sign the final paperwork and officially take ownership of the home.
What does the acronym PITI stand for in the context of a monthly mortgage payment?
In a typical amortization schedule, what happens to the portion of your payment that goes towards principal over the life of the loan?
Understanding these basics is the first step toward navigating the home-buying process with confidence.

