Mortgage Refinance Math
Understanding Mortgage Basics
What is a mortgage?
A mortgage is a loan used to buy a home. It’s that simple. When you take out a mortgage, a lender gives you a large sum of money to purchase a property. In return, you agree to pay back that money, plus interest, over a set period. The house itself acts as collateral for the loan. This means if you stop making payments, the lender has the right to take the property.
The building blocks of a mortgage
Every mortgage is made up of a few key components. Understanding them is crucial to understanding your loan.
Principal
noun
The total amount of money you borrow from the lender. If you get a $300,000 loan to buy a house, your principal is $300,000.
Next up is the cost of borrowing that money.
Interest
noun
The fee you pay to the lender for borrowing the principal. It’s usually expressed as a percentage, known as the interest rate.
This is how long you have to pay everything back.
Term
noun
The length of time you have to repay the loan. Common mortgage terms are 15 years and 30 years.
These three elements work together to determine your monthly payment. The process of paying down your loan over time through regular installments is called amortization. Each payment you make is split between paying off interest and reducing your principal.
At the beginning of your loan, a larger portion of your payment goes toward interest. As time goes on, more and more of your payment starts chipping away at the principal. This is how you gradually build ownership, or equity, in your home.
Fixed vs adjustable rates
Mortgages generally fall into two categories based on how their interest rate is structured: fixed-rate and adjustable-rate.
A fixed-rate mortgage has an interest rate that stays the same for the entire term of the loan. Your monthly payment for principal and interest never changes. This predictability makes budgeting easier, as you always know what to expect.
An adjustable-rate mortgage, or ARM, is a bit different. It typically starts with a lower, fixed interest rate for an initial period, such as five or seven years. After that period ends, the interest rate changes at regular intervals, often once a year. The new rate is based on a benchmark index, so your monthly payments can go up or down. ARMs often have caps that limit how much the rate can increase at one time and over the life of the loan.
| Feature | Fixed-Rate Mortgage | Adjustable-Rate Mortgage (ARM) |
|---|---|---|
| Interest Rate | Stays the same for the life of the loan. | Changes after an initial fixed period. |
| Monthly Payment | Consistent and predictable. | Can increase or decrease over time. |
| Best For | Buyers who plan to stay in their home long-term and prefer stable payments. | Buyers who may sell before the fixed period ends or who can handle potential payment increases. |
Choosing the right type of mortgage depends on your financial situation and how long you plan to stay in the home. Now, let's test what you've learned.
In the early stages of paying off a mortgage, the majority of your monthly payment is typically applied to the:
What is the primary advantage of a fixed-rate mortgage?
Understanding these core concepts is the first step toward navigating the home-buying process with confidence.