Mortgage Calculator

Calculate your mortgage payments and see detailed amortization schedules. Compare different loan terms and interest rates.

What Is a Mortgage Calculator?

A mortgage calculator is a financial planning tool that estimates the monthly payment and total cost of a home loan based on the purchase price, down payment, interest rate, and loan term. It combines the core principal-and-interest calculation with additional recurring costs such as property taxes, homeowner's insurance, private mortgage insurance, and homeowners association fees to give you a realistic picture of what homeownership will cost each month.

Understanding your projected payment before you begin house hunting sets realistic expectations and helps you determine how much home you can afford. Lenders generally recommend that total housing costs not exceed 28 percent of gross monthly income, a guideline known as the front-end debt-to-income ratio. By adjusting inputs in the calculator, you can see exactly how changes to the down payment, interest rate, or loan term shift the numbers.

How Mortgage Math Works

The centerpiece of mortgage math is the fixed-rate amortization formula. For a loan with principal P, monthly interest rate r, and total payments n:

Monthly Payment = P x [r(1 + r)^n] / [(1 + r)^n - 1]

Here, r is the annual interest rate divided by 12 and n is the loan term in years multiplied by 12. This formula produces a constant monthly payment that, over the life of the loan, fully repays both the principal and all accrued interest.

Each monthly payment is split between interest and principal repayment. In the early years, the interest portion dominates because it is calculated on the large outstanding balance. As the balance decreases, a progressively larger share of each payment goes toward principal. This shifting allocation is visible in the amortization table.

On top of principal and interest, lenders typically escrow property taxes and insurance, collecting them monthly and paying the bills on your behalf. PMI applies when the loan-to-value ratio exceeds 80 percent, and HOA dues add a fixed monthly charge for shared community amenities and maintenance.

How to Use This Calculator

Enter the home price. This is the total purchase price of the property. The calculator accepts any positive number.
Set your down payment. You can enter either a dollar amount or a percentage. The two fields stay synchronized: changing one automatically updates the other based on the home price. A typical down payment ranges from 3.5 to 20 percent depending on the loan program.
Enter the interest rate and loan term. Type the annual interest rate as a percentage (for example, 6.5 for 6.5%) and the loan term in years. Common terms are 15 and 30 years, though some lenders offer 10, 20, or 25-year options.
Fill in additional costs. Enter your estimated annual property tax and annual home insurance premium. The calculator divides these by 12 to add to your monthly total. Enter PMI and HOA fees as monthly amounts since that is how they are typically billed.
Review the monthly breakdown. The results section shows your total monthly payment along with a line-item breakdown of each component. The highlighted total at the top gives you the full monthly obligation at a glance.
Examine the loan summary. This section shows the total interest you will pay over the life of the loan and the total cost of the principal-and-interest portion. These numbers reveal the true long-term cost of borrowing.
Study the amortization table. The first 12 monthly payments are displayed in table form, showing how each payment splits between principal and interest and how the remaining balance decreases month by month.

Worked Examples

Example 1: Standard 30-Year Mortgage

Home price $350,000, down payment $70,000 (20%), interest rate 6.5%, 30-year term. The principal is $280,000. Monthly P&I is approximately $1,770. With $3,600 annual property tax ($300/month), $1,400 annual insurance ($117/month), no PMI (20% down), and no HOA, the total monthly payment is roughly $2,187.

Example 2: Starter Home with PMI

Home price $225,000, down payment $11,250 (5%), interest rate 7.0%, 30-year term. Principal is $213,750. Monthly P&I is about $1,422. PMI at $160/month, property tax at $200/month, insurance at $100/month. Total monthly payment is approximately $1,882. The buyer would need to accumulate 20% equity to eliminate the $160 PMI charge.

Example 3: 15-Year Accelerated Payoff

Home price $400,000, down payment $80,000 (20%), interest rate 5.75%, 15-year term. Principal is $320,000. Monthly P&I jumps to about $2,657 compared to $1,867 on a 30-year term. However, total interest over 15 years is approximately $158,228 versus $352,135 over 30 years, saving nearly $194,000.

Example 4: Condo with HOA Fees

Home price $280,000, down payment $56,000 (20%), interest rate 6.25%, 30-year term. Principal is $224,000. Monthly P&I is about $1,379. Property tax $250/month, insurance $92/month, HOA $350/month. Total monthly obligation is $2,071, with the HOA representing almost 17% of the total payment.

Common Use Cases

Pre-qualification planning: Determine how much home you can afford before applying for a mortgage by working backward from your comfortable monthly payment to the purchase price.
Rate shopping comparison: Enter quotes from multiple lenders to see how even small interest rate differences affect your monthly payment and total interest over the life of the loan.
Refinance analysis: Compare your current payment to a potential refinance scenario with a lower rate or shorter term to see if refinancing makes financial sense.
Budget impact assessment: Model how additional costs like HOA fees or higher property tax rates in different neighborhoods change your total monthly obligation.
Extra payment planning: Use the amortization table to understand how much of your early payments go to interest and to motivate making additional principal payments when possible.

Tips and Common Mistakes

Do not forget to include all housing costs in your budget. The principal-and-interest payment alone understates true housing expenses. Property taxes, insurance, PMI, HOA dues, and maintenance can easily add 30 to 50 percent on top of the base payment.

Do not ignore the effect of small rate differences. A quarter-point increase in interest rate on a $300,000 30-year loan adds roughly $50 per month and over $17,000 in total interest. Shopping aggressively for the best rate pays off substantially.

Remember that property taxes can increase. The amount you enter today is an estimate. Municipalities reassess property values periodically, which can raise your tax bill and your escrowed monthly payment.

Plan for PMI removal. If you start with less than 20 percent down, track your equity growth. Once you reach 20 percent equity based on the original purchase price, contact your lender to cancel PMI. Some loans allow cancellation based on a new appraisal showing sufficient equity from appreciation.

Use the amortization table to strategize. Notice how little principal you pay in the first year. Making even one extra payment per year, applied directly to principal, can shave years off your mortgage and save tens of thousands in interest.

Frequently Asked Questions

How is the monthly mortgage payment calculated?

The monthly principal and interest payment uses the standard amortization formula: M = P[r(1+r)^n] / [(1+r)^n - 1], where P is the loan principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. This formula ensures each payment covers that month's interest charge plus a portion of the principal, with the balance reaching zero at the end of the loan term.

What is PMI and when is it required?

Private Mortgage Insurance (PMI) is a monthly premium that lenders require when the borrower's down payment is less than 20 percent of the home's purchase price. PMI protects the lender against default risk. The cost typically ranges from 0.3 to 1.5 percent of the original loan amount per year. Once you reach 20 percent equity in the home through payments or appreciation, you can usually request PMI cancellation from your lender.

Should I choose a 15-year or 30-year mortgage?

A 15-year mortgage has higher monthly payments but saves significantly on total interest. A 30-year mortgage lowers monthly obligations but costs more over the life of the loan. For example, a $240,000 loan at 6.5% costs about $2,072 per month over 15 years with $132,955 in total interest, versus $1,517 per month over 30 years with $306,108 in total interest. Choose based on your monthly budget and long-term financial goals.

How does the down payment affect my mortgage costs?

A larger down payment reduces the loan principal, which directly lowers your monthly payment and the total interest paid over the life of the loan. Putting down 20 percent or more also eliminates the need for PMI, saving an additional monthly expense. On a $300,000 home, increasing the down payment from 10 to 20 percent saves approximately $150 to $250 per month depending on the interest rate and PMI cost.

What costs are not included in this calculator?

This calculator covers principal, interest, property tax, home insurance, PMI, and HOA fees. It does not include closing costs (typically 2 to 5 percent of the loan amount), title insurance, home inspection fees, appraisal costs, mortgage origination fees, or ongoing maintenance expenses. These one-time and recurring costs should be factored into your total home-buying budget separately.

How do property taxes affect my monthly payment?

Property taxes are typically collected monthly as part of your mortgage payment and held in an escrow account managed by your lender. The annual tax amount is divided by 12 and added to your principal and interest payment. Property tax rates vary widely by location, generally ranging from 0.5 to 2.5 percent of the home's assessed value per year. This calculator divides your entered annual property tax by 12 automatically.

What interest rate should I expect for a mortgage?

Mortgage interest rates fluctuate based on market conditions, Federal Reserve policy, your credit score, down payment size, and loan type. As of early 2026, 30-year fixed rates hover around 6 to 7 percent, though individual offers vary. A higher credit score, larger down payment, and shorter loan term generally qualify you for a lower rate. Try adjusting the rate in the calculator to see how even a quarter-point change affects your payment.

How do I read the amortization table?

The amortization table shows how each monthly payment is split between principal and interest. Early in the loan, most of each payment goes to interest because the outstanding balance is large. As you make payments and the balance shrinks, a larger portion goes to principal. The table displayed shows the first 12 months so you can see this shift beginning. The balance column shows how much you still owe after each payment.