Mortgage Calculator – Estimate Your Monthly Mortgage Payment

Your Mortgage Details

Home Price

Down Payment

Annual Interest Rate

Loan Term

yrs

Results

Enter your details and hit Calculate

What is a Mortgage Calculator?

A mortgage calculator is a tool that estimates your monthly mortgage payment based on the home price, down payment, interest rate, and loan term you provide. It uses the same amortization formula that lenders apply when structuring your loan, giving you an accurate picture of your monthly obligation before you commit to a purchase.

The most important number a mortgage calculator produces is your monthly payment — the fixed amount you will owe each month for the life of the loan. But the total cost is equally important: a 30-year mortgage at 6.8% on a $400,000 home does not cost $400,000. It costs significantly more once interest is factored in, and understanding that gap is essential for making a confident homebuying decision.

Mortgage calculators are also invaluable for comparison shopping. By adjusting the interest rate, down payment, or loan term, you can immediately see how each variable affects your payment and total cost — helping you evaluate different loan offers and understand the long-term trade-offs of each option.

Mortgage Payment Formula Explained

Mortgages use the standard loan amortization formula, which calculates a fixed monthly payment that covers both principal and interest over the life of the loan:

M = L × r(1 + r)ⁿ(1 + r)ⁿ − 1

M — Monthly payment: the fixed amount you pay each month.
L — Loan amount: home price minus your down payment.
r — Monthly interest rate: annual rate ÷ 12 (e.g. 6.8% ÷ 12 = 0.5667% per month).
n — Total number of payments: loan term in years × 12.

The loan amount is the home price minus the down payment. If you buy a $400,000 home with an $80,000 down payment, your loan amount is $320,000. The formula ensures that every monthly payment is the same, but the proportion going toward interest versus principal shifts over time — early payments are mostly interest, while payments near the end are mostly principal.

Note: This calculator covers principal and interest only. Your actual monthly payment to a lender will typically also include property taxes, homeowner's insurance, and possibly private mortgage insurance (PMI) if your down payment is less than 20%.

Example: A $400,000 Home Purchase

Suppose you are buying a $400,000 home with a $80,000 down payment (20%), leaving a loan amount of $320,000. Here is how your payment and total cost vary by interest rate and term:

Rate	Term	Monthly Payment	Total Interest	Total Cost
5.0%	30 yrs	$1,718	$298,374	$618,374
6.0%	30 yrs	$1,919	$370,893	$690,893
6.8%	30 yrs	$2,093	$433,511	$753,511
6.8%	15 yrs	$2,840	$191,153	$511,153

The highlighted row shows a typical scenario at today's rates. Notice how the 15-year mortgage at 6.8% has a higher monthly payment ($2,840 vs $2,093), but saves over $242,000 in total interest compared to the 30-year option at the same rate. Choosing between a 15-year and 30-year mortgage is one of the most impactful financial decisions a homebuyer can make.

Values calculated using standard amortization on a $320,000 loan (principal + interest only). Actual payments will include taxes, insurance, and possible PMI. For illustrative purposes only.

Frequently Asked Questions

How much house can I afford?

A widely used rule of thumb is that your total housing payment (principal, interest, taxes, and insurance) should not exceed 28% of your gross monthly income. Some lenders extend this to 31%. Separately, your total monthly debt payments — including your mortgage, car loans, student loans, and credit cards — should ideally stay below 36–43% of your gross income (your debt-to-income ratio). Use this calculator to find a monthly payment you can afford, then work backwards to determine the maximum home price and loan amount that fits your budget.

What is the difference between a 15-year and 30-year mortgage?

A 15-year mortgage has a higher monthly payment but builds equity faster and saves a substantial amount in total interest — often hundreds of thousands of dollars on a large loan. A 30-year mortgage spreads payments over twice as long, making monthly payments lower and more manageable, but at the cost of paying far more interest over time. The right choice depends on your income stability, cash flow needs, and financial goals. Many homeowners choose the 30-year for flexibility and invest the monthly payment difference in the market, potentially coming out ahead if investment returns exceed the mortgage rate.

How does the down payment affect my mortgage?

A larger down payment reduces your loan amount, which directly lowers your monthly payment and the total interest you pay over the life of the loan. Putting down 20% or more also eliminates the need for private mortgage insurance (PMI), which can add 0.5–1.5% of the loan amount per year to your costs. Additionally, a larger down payment can help you qualify for a better interest rate, as lenders view lower loan-to-value (LTV) ratios as less risky. Even increasing a down payment from 10% to 20% on a $400,000 home saves $40,000 in loan principal plus avoids years of PMI payments.

Should I choose a fixed-rate or adjustable-rate mortgage?

A fixed-rate mortgage locks in your interest rate for the entire loan term, giving you a predictable payment regardless of market conditions — ideal if you plan to stay in the home long-term or value payment stability. An adjustable-rate mortgage (ARM) starts with a lower fixed rate for an initial period (typically 5, 7, or 10 years), then adjusts periodically based on a market index. ARMs can save money if you sell or refinance before the adjustment period, but carry the risk of payment increases if rates rise. This calculator models a fixed-rate mortgage. For ARMs, calculations would need to factor in rate caps and adjustment schedules.

Does this calculator include property taxes and insurance?

No — this calculator covers principal and interest only, which is the portion of your mortgage payment that your lender determines based on loan amount, rate, and term. Your actual monthly housing cost will also include property taxes (typically 0.5–2.5% of home value per year, divided into 12 monthly payments), homeowner's insurance (roughly $100–$300/month for a $400,000 home), and potentially PMI if your down payment is below 20%. These additional costs can add $500–$1,500 or more per month, so factor them in when assessing total affordability.