Mortgage Calculator

Understanding Your Mortgage Payment

A mortgage is a long-term loan secured by the home you are buying. Each monthly payment is split between principal (the portion that reduces your outstanding loan balance) and interest (the cost the lender charges for borrowing the money). This calculator computes the fixed principal-and-interest payment for a standard fixed-rate mortgage and then maps out exactly how that payment is applied over every month and year of the loan.

The math behind it is the standard amortization formula: M = P[r(1+r)^n] / [(1+r)^n − 1]. Here P is the loan amount (home price minus down payment), r is the monthly interest rate (the annual rate divided by 12), and n is the total number of monthly payments (years multiplied by 12). The formula solves for the constant payment M that pays the loan down to exactly zero by the final month.

A Worked Example

Suppose you buy a home priced at $300,000 and put 20% down, leaving a loan of $240,000. At a hypothetical 6% annual rate over 30 years, the monthly rate is 0.5% (0.06 ÷ 12) and there are 360 payments. Plugging these into the formula produces a principal-and-interest payment of roughly $1,439 per month. In the very first payment, about $1,200 goes to interest and only around $239 to principal. By the final years that ratio flips, with almost the entire payment reducing your balance. Try entering these numbers above to watch the breakdown update in real time.

Factors That Affect Your Payment

Your monthly mortgage payment depends on four key inputs. Adjusting any one of them changes both your payment and the total interest you pay:

• Home price: A higher price means a larger loan and a higher payment, assuming the same down payment percentage.
• Down payment: A bigger down payment shrinks the loan amount, lowers the payment, and can help you avoid private mortgage insurance.
• Interest rate: Even a small rate change has an outsized effect over 30 years. Shopping multiple lenders is one of the highest-value steps you can take.
• Loan term: A longer term lowers the monthly payment but increases the total interest paid; a shorter term does the reverse.

Interpreting the Results and Common Mistakes

The single most useful number to watch is total interest paid, shown alongside your monthly payment. It reveals the true lifetime cost of the loan, which is often a striking share of the amount borrowed. A frequent mistake is shopping only by monthly payment: stretching to a longer term can make a payment look affordable while quietly adding tens of thousands of dollars in interest. Another common oversight is forgetting that this figure covers principal and interest only. Property taxes, homeowners insurance, PMI, and any HOA dues are billed on top and should be part of your real housing budget.

How to Lower Your Mortgage Payment

Several strategies can reduce your monthly payment, each with a trade-off. Increasing your down payment or choosing a less expensive home directly shrinks the loan. Securing a lower interest rate through rate shopping or by paying discount points reduces the cost of borrowing. Extending the loan term lowers the monthly payment but raises total interest, so weigh short-term cash flow against long-term cost. Making extra principal payments later on can also shorten the loan dramatically.

Building Equity Over Time

Equity is the share of the home you actually own, equal to its value minus your remaining loan balance. It grows two ways: as you pay down principal and as the property potentially appreciates. Because early payments are mostly interest, equity from principal builds slowly at first and accelerates in the later years of the loan, which the amortization schedule below makes clear. Reaching roughly 20% equity is a common milestone, since it is the point at which private mortgage insurance can typically be removed, lowering your overall housing cost.

Many lenders also collect property taxes and homeowners insurance through an escrow account, adding those amounts to your monthly bill and paying them on your behalf when due. That is why your actual payment to the lender is often noticeably higher than the principal-and-interest figure this calculator shows. Knowing the difference helps you budget for the true monthly cost of owning the home rather than just servicing the loan.

When to Use a Different Calculator

Use this mortgage calculator for home purchases and refinances on fixed-rate loans. If you want to study how additional principal payments accelerate payoff, the amortization calculator lets you add an extra monthly amount. For a car purchase, the auto loan calculator factors in trade-in value and sales tax, and for general installment debt the loan calculator handles any fixed-rate balance.