Mortgage Calculator
Calculate your monthly mortgage payment with taxes, insurance, and PMI. See the full cost breakdown, amortization schedule, and how extra payments can save you thousands.
What Is a Mortgage Payment?
A mortgage payment is a recurring obligation made to a lender in exchange for borrowing money to purchase a home. Each payment consists of two core components: principal and interest. The principal portion reduces the outstanding balance of the loan, while the interest portion compensates the lender for the risk and opportunity cost of lending the funds.
Beyond principal and interest, homeowners often pay additional amounts bundled into their monthly bill. Property taxes, homeowners insurance, and private mortgage insurance (PMI) are frequently collected by the lender through an escrow account and paid on the borrower's behalf. These items are sometimes referred to collectively as PITI: principal, interest, taxes, and insurance.
The process by which a loan is gradually paid off through scheduled payments is called amortization. At the start of a 30-year mortgage, roughly two-thirds of each payment may go toward interest, with only one-third reducing the principal. By the final years, that ratio reverses almost entirely. This front-loaded interest structure means that borrowers who sell or refinance early in the loan term will have repaid relatively little of the original balance despite making years of payments. Understanding this dynamic is essential when evaluating how much equity you are actually building each month versus how much is going to the lender as profit.
How Mortgage Interest Rates Work
Mortgage interest rates represent the annual cost of borrowing money expressed as a percentage of the remaining loan balance. The two primary rate structures are fixed-rate and adjustable-rate mortgages. A fixed-rate mortgage locks in the same interest rate for the entire loan term, providing predictable payments that never change. An adjustable-rate mortgage (ARM) begins with a lower introductory rate that resets periodically based on a benchmark index, meaning your payment can rise or fall over time.
Several factors determine the rate a lender offers you. Your credit score is among the most influential: borrowers with scores above 740 typically qualify for the lowest available rates, while those below 620 may face significantly higher costs or difficulty obtaining approval. The loan-to-value ratio matters as well, since lenders view smaller loans relative to the property value as less risky. The loan term also plays a role, with 15-year mortgages generally carrying lower rates than 30-year options because the lender's money is at risk for a shorter period.
Broader economic forces drive the baseline for all mortgage rates. The Federal Reserve's monetary policy, inflation expectations, and investor demand for mortgage-backed securities all influence where rates settle on any given day. Even a small difference in rate has an outsized impact over the life of a loan. On a $300,000 mortgage, a half-percentage-point reduction can save tens of thousands of dollars in total interest paid.
Understanding Amortization
Amortization is the systematic process of paying down a debt through equal installments over a defined period. With each mortgage payment, a portion goes to interest on the current balance and the remainder reduces the principal. Because interest is calculated on the outstanding balance, the interest charge shrinks with every payment, and the principal portion grows proportionally. This creates a predictable schedule where the borrower makes identical payments but steadily shifts the composition from interest-heavy to principal-heavy.
An amortization schedule is a table that maps out every single payment over the life of the loan. It shows the exact split between principal and interest for each month, along with the remaining balance after each payment. Reviewing this schedule reveals how slowly equity builds in the early years and how dramatically it accelerates toward the end. On a 30-year loan at 6.5%, a borrower will not reach the halfway point of principal repayment until roughly year 22.
Extra payments can substantially alter this timeline. Adding even a modest amount to each monthly payment reduces the principal faster, which in turn reduces the interest charged in subsequent months. A homeowner who adds $200 per month to a $240,000 mortgage at 6.5% could shave roughly six years off the loan and save over $70,000 in interest. Some borrowers achieve similar results by making biweekly half-payments instead of monthly ones, which results in one extra full payment per year.
Down Payment and Private Mortgage Insurance
The down payment is the portion of a home's purchase price that the buyer pays upfront from personal funds rather than borrowing. It directly reduces the loan amount, which lowers both the monthly payment and the total interest paid over the life of the mortgage. A larger down payment also gives the buyer immediate equity in the property, providing a financial cushion if home values decline.
Lenders use the loan-to-value (LTV) ratio to assess risk. This ratio divides the mortgage amount by the appraised value of the home. When a buyer puts down less than 20%, the LTV exceeds 80%, and most conventional lenders require private mortgage insurance. PMI protects the lender in case the borrower defaults and typically costs between 0.5% and 1.5% of the original loan amount per year. On a $280,000 loan, that can add $115 to $350 per month to the housing cost.
PMI is not permanent on conventional loans. Once the borrower's equity reaches 20% of the original property value through payments or appreciation, they can request cancellation. By law, the lender must automatically terminate PMI when equity reaches 22%. Government-backed loans follow different rules: FHA loans require mortgage insurance premiums for the entire loan term if the down payment is below 10%, while VA and USDA loans use funding fees instead of traditional PMI. Buyers should factor these ongoing costs into their budget when deciding how much to put down.
How Extra Payments Save You Money
Making extra payments on your mortgage is one of the most effective ways to build equity faster and reduce the total cost of homeownership. When you pay more than the required monthly amount, the entire extra portion goes directly toward reducing the principal balance. Since interest is calculated on the remaining balance each month, a lower principal means less interest accrues going forward. This creates a compounding savings effect that grows stronger over time.
Consider a $300,000 loan at 6.5% over 30 years. The standard monthly payment is about $1,896, and you'd pay roughly $382,000 in total interest. Adding just $200 per month to your payment could cut about six years off the loan term and save over $80,000 in interest. Bump that extra amount to $500 per month, and you might shave more than 11 years off the mortgage while saving over $150,000.
There are several strategies for making extra payments. Some homeowners simply round up their payment to the nearest hundred. Others make one additional full payment each year, often using a tax refund or bonus. Biweekly payment plans split the monthly amount in half and pay every two weeks, which results in 26 half-payments (13 full payments) per year instead of the usual 12. Before committing to extra payments, verify with your lender that there are no prepayment penalties and that extra funds are applied to principal rather than being held for the next scheduled payment.
Formula
M = P × [r(1+r)^n] / [(1+r)^n - 1]
This formula calculates the fixed monthly payment needed to fully repay a loan over a set number of periods at a constant interest rate. Each payment covers a portion of the outstanding principal plus the interest accrued that month. Early in the loan, most of each payment goes toward interest. As the balance decreases, a larger share of each payment is applied to principal. This shift happens naturally through amortization without any change to the payment amount itself. The total monthly housing cost (PITI) adds property taxes, homeowners insurance, private mortgage insurance, and HOA fees to the base principal-and-interest payment. Extra monthly payments reduce the principal faster, which shortens the loan term and lowers total interest paid.
Where:
- M = The fixed monthly payment amount for principal and interest.
- P = The amount borrowed, calculated as the home price minus the down payment.
- r = The annual interest rate divided by 12. For example, a 6% annual rate becomes 0.005 per month.
- n = The loan term in years multiplied by 12. A 30-year mortgage has 360 total payments.
Example Calculations
First-Time Homebuyer
A first-time buyer purchases a $350,000 home with 10% down at a 6.75% fixed rate on a 30-year term.
- Calculate the loan principal: $350,000 - $35,000 = $315,000
- Convert the annual rate to a monthly rate: 6.75% / 12 = 0.5625% = 0.005625
- Determine total number of payments: 30 years x 12 months = 360 payments
- Apply the formula: M = $315,000 x [0.005625(1.005625)^360] / [(1.005625)^360 - 1]
- Calculate (1.005625)^360 = 7.5068
- Numerator: $315,000 x (0.005625 x 7.5068) = $315,000 x 0.042226 = $13,301.10
- Denominator: 7.5068 - 1 = 6.5068
- Monthly payment: $13,301.10 / 6.5068 = $2,044.30
With a 90% LTV ratio, this buyer will need private mortgage insurance until they reach 20% equity. At roughly $165/month for PMI, the true monthly housing cost starts closer to $2,209 before taxes and insurance are added.
Refinancing to a Lower Rate
A homeowner with a $250,000 remaining balance refinances from a 7.5% rate to a 5.75% rate on a new 30-year term.
- Original loan at 7.5%: monthly rate = 0.625%, n = 360
- Original monthly payment: M = $250,000 x [0.00625(1.00625)^360] / [(1.00625)^360 - 1] = $1,748.04
- Original total interest over 30 years: ($1,748.04 x 360) - $250,000 = $379,294.40
- Refinanced loan at 5.75%: monthly rate = 0.4792%, n = 360
- Refinanced monthly payment: M = $250,000 x [0.004792(1.004792)^360] / [(1.004792)^360 - 1] = $1,459.07
- Refinanced total interest over 30 years: ($1,459.07 x 360) - $250,000 = $275,265.20
- Monthly savings: $1,748.04 - $1,459.07 = $288.97
- Total interest savings: $379,294.40 - $275,265.20 = $104,029.20
While the interest savings are substantial, borrowers should factor in closing costs, which typically range from 2% to 5% of the loan amount. On a $250,000 refinance, closing costs of $7,500 would take about 26 months of savings to recoup, making the refinance worthwhile only if the homeowner plans to stay in the home for at least that long.
15-Year vs. 30-Year Term Comparison
Comparing a $280,000 loan at 6.25% over 15 years versus 30 years to see how the term affects total cost.
- 30-year loan: monthly rate = 0.5208%, n = 360
- 30-year monthly payment: M = $280,000 x [0.005208(1.005208)^360] / [(1.005208)^360 - 1] = $1,724.16
- 30-year total paid: $1,724.16 x 360 = $620,697.60
- 30-year total interest: $620,697.60 - $280,000 = $340,697.60
- 15-year loan: monthly rate = 0.5208%, n = 180
- 15-year monthly payment: M = $280,000 x [0.005208(1.005208)^180] / [(1.005208)^180 - 1] = $2,401.03
- 15-year total paid: $2,401.03 x 180 = $432,185.40
- 15-year total interest: $432,185.40 - $280,000 = $152,185.40
- Monthly payment difference: $2,401.03 - $1,724.16 = $676.87 more per month
- Total interest savings with 15-year: $340,697.60 - $152,185.40 = $188,512.20
The 15-year mortgage costs $677 more per month but saves over $188,000 in interest. Additionally, 15-year mortgages often qualify for slightly lower interest rates than shown here, which would widen the savings further. However, the higher monthly payment reduces financial flexibility, so borrowers should ensure they have an adequate emergency fund before choosing the shorter term.
Impact of Extra Monthly Payments
A homeowner with a $300,000 loan at 6.5% over 30 years adds $200 per month in extra payments to accelerate payoff.
- Standard monthly payment: M = $300,000 x [0.005417(1.005417)^360] / [(1.005417)^360 - 1] = $1,896.20
- Standard total interest over 30 years: ($1,896.20 x 360) - $300,000 = $382,632.00
- With $200 extra per month, the effective payment is $2,096.20
- Extra payments reduce principal faster, cutting interest each subsequent month
- New payoff time: approximately 23 years and 7 months (283 payments instead of 360)
- Total interest with extra payments: approximately $296,500
- Interest saved: $382,632 - $296,500 = approximately $86,132
- Time saved: about 6 years and 5 months
The extra $200 per month costs $72,000 over the life of the shorter loan ($200 x 360 months maximum), but it saves over $86,000 in interest while also freeing the borrower from mortgage payments more than six years early. That's a net benefit of roughly $14,000 plus six years of financial freedom.
Frequently Asked Questions
Most financial advisors recommend keeping your total monthly housing costs below 28% of your gross monthly income. This includes principal, interest, taxes, insurance, and any HOA fees. Lenders may approve you for more, sometimes up to 36% of income, but stretching to the maximum approval amount leaves little room for other financial goals or unexpected expenses. Factor in your existing debts, savings rate, and lifestyle costs before settling on a price range.
The interest rate is the annual cost of borrowing the principal, expressed as a percentage. The APR, or annual percentage rate, includes the interest rate plus additional lender fees such as origination charges, discount points, and certain closing costs, spread over the loan term. APR gives a more complete picture of the true borrowing cost and is required by law to be disclosed alongside the interest rate. When comparing offers from different lenders, APR is typically the more useful number for an apples-to-apples comparison.
A 30-year mortgage offers lower monthly payments and greater cash flow flexibility, which can be directed toward investments, emergency savings, or other goals. A 15-year mortgage builds equity faster, typically carries a lower interest rate, and saves a significant amount in total interest. Choose the 15-year term if the higher payment fits comfortably within your budget and you already have solid savings. If the larger payment would strain your finances or prevent retirement contributions, the 30-year term is the more prudent choice.
Extra payments go directly toward reducing the principal balance. Since interest is calculated on the outstanding balance each month, lowering the principal means less interest accrues in every subsequent period. This creates a compounding benefit where each extra dollar paid saves more than its face value over time. Even small additional amounts, such as rounding up to the nearest hundred or making one extra payment per year, can shorten a 30-year loan by several years and save tens of thousands of dollars in interest.
Homeownership involves several recurring costs beyond principal and interest. Property taxes vary widely by location but often range from 0.5% to 2.5% of the home's assessed value annually. Homeowners insurance typically costs $1,000 to $3,000 per year depending on coverage and location. If your down payment is below 20%, expect to pay private mortgage insurance. Maintenance and repairs generally run 1% to 2% of the home's value per year. HOA fees, utility bills, and potential special assessments should also be factored into your monthly budget.
An escrow account is a holding account managed by your mortgage servicer to pay property taxes and homeowners insurance on your behalf. Each month, a portion of your mortgage payment is deposited into this account, and the servicer disburses funds when tax and insurance bills come due. Lenders require escrow accounts to ensure these obligations are met, protecting their collateral. Your escrow payment is reviewed annually and may adjust if tax assessments or insurance premiums change, which can cause your total monthly payment to increase or decrease.
PITI stands for principal, interest, taxes, and insurance, which together make up your total monthly housing payment. Principal and interest come from the mortgage formula based on your loan amount, rate, and term. Property taxes are your annual assessment divided by 12. Insurance includes homeowners insurance and, if applicable, private mortgage insurance. Add HOA fees if your property has them. Lenders use your total PITI to determine whether you can afford the loan, typically requiring it to stay below 28% of your gross monthly income.
The savings depend on your loan size, interest rate, and how much extra you pay. As a rough guide, on a $300,000 loan at 6.5% over 30 years, adding $100 per month saves about $50,000 in interest and cuts 4 years off the term. Doubling that to $200 extra per month saves roughly $86,000 and shortens the loan by over 6 years. The earlier you start making extra payments, the more you save, because you avoid interest on a larger portion of the balance for more years.