Mortgage interest calculator

By Allstate

Last updated: January 1

Buying a home is an exciting time but mortgages, interest rates and understanding what your costs are can be difficult. This mortgage interest calculator can help you estimate your monthly mortgage payment if you have an interest-only mortgage. To get an estimate and breakdown of your interest-only mortgage, just fill out some basic information about the purchase price, down payment, term, interest-only period, and interest rate.

An interest-only mortgage is a loan in which you pay only interest payments for a specified period at the beginning of the loan agreement. After that, borrowers may refinance their loan or pay a higher monthly payment until the loan and interest is repaid.

This mortgage interest calculator shows monthly payments both during and after the interest-only period and assumes that the interest-only period has a fixed rate.

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Mortgage interest calculator terms you need to know

Use the definitions in this section to make sure that you understand what information you’re being asked for and why.

Purchase Price

The purchase price refers to the value or price of the asset that you are interested in taking a mortgage out on.

Down payment

A down payment on a house is an amount of money which is some percentage of the purchase price of the property. The more you put down, the less you’ll have to pay each month.

Loan program

Loan programs for a mortgage typically come in a 15-year or 30-year structure. This impacts the length of time that the borrower will take to repay the loan and the amount of interest that accrues over that period of time. A 15-year mortgages have higher monthly payments but typically lower interest rates than 30-year mortgages.

Interest rate

The interest rate is the rate at which interest grows on your loan. This is typically expressed as a yearly rate. A 4% interest rate mortgage, for example, would grow 0.25% interest over the course of 12 months.

Property tax

Property tax is a tax applied to the value of a property. This tax is implemented by a local government and is paid for by the property owner.

Homeowners insurance

Homeowners insurance typically covers theft, fire and smoke damage, damage caused by hail, falling objects, frozen pipes and water damage from plumbing.

HOA dues

Homeowner Associations (HOAs) are groups of private homeowners that create and enforce rules for residents, according to Freddie Mac. HOA dues are generally fees paid by residents to help with necessary maintenance or repairs in common areas.

How does mortgage interest work?

In short, a mortgage interest is a percentage of your loan. Most mortgages use simple interest, which means that borrowers will pay interest that is calculated on the principal amount of the loan, according to Quicken Loans. The formula for simple interest is straightforward:

Simple Interest = Principal x Interest Rate x Loan term in years

Mortgage interest FAQs