Mortgage calculator
Free mortgage calculator for a fixed-rate loan. Estimate monthly principal and interest, add your property tax and insurance, and review total interest.
By Calcr · Updated
Free mortgage calculator for fixed-rate monthly payments
Estimate a fixed-rate loan's monthly principal and interest, then add your entered property tax and home insurance amounts. This free mortgage calculator also shows scheduled interest over the full term. Enter the amount borrowed after the down payment, rather than the property's purchase price. The result is an illustrative payment estimate, not a lender quote, approval or affordability decision.
Set up the loan correctly
Use the fixed nominal annual interest rate stated for the loan, not an APR that also reflects certain borrowing costs. Select a whole number of years from 1 to 50. The model assumes twelve equal payment periods per year, a fixed rate throughout and payments at the end of each month. It does not model adjustable rates, interest-only periods, balloon payments or a different day-count convention.
Enter annual property tax and annual home insurance separately. The tool divides each by twelve for a monthly estimate. Enter zero if you want to examine principal and interest alone, but remember that zero in a field means excluded from this scenario, not necessarily absent from real homeownership. Taxes and insurance can change even when a fixed-rate loan's principal-and-interest payment stays the same.
Mortgage payment formula
Let P be the loan amount, r the nominal annual rate divided by 12 and expressed as a decimal, and n the number of monthly payments. Monthly principal and interest is P * r / (1 - (1 + r)^(-n)). At a zero interest rate, use P / n instead, avoiding division by zero in the standard formula.
Scheduled interest equals the unrounded monthly principal-and-interest payment multiplied by n, minus P. The displayed monthly amount rounds to cents. A lender's final payment can differ slightly because real schedules may round each payment or handle partial periods differently. The total-interest figure does not include property tax, insurance, fees or the down payment.
The CFPB explanation of PITI separates principal, interest, taxes and insurance. Its payment comparison guidance also explains that mortgage insurance and other costs may be additional. This calculator does not infer PMI or HOA fees, so add those separately when examining a real budget.
Worked mortgage examples
A thirty-year fixed-rate scenario
For a $300,000 loan at 6% over 30 years, r is 0.005 and n is 360. Monthly principal and interest is approximately $1,798.65. Annual property tax of $3,600 adds $300 per month, and insurance of $1,200 adds $100. The displayed monthly estimate including those entered amounts is $2,198.65. Scheduled interest over the loan term is approximately $347,514.57, using unrounded payments.
This example assumes the $300,000 is the loan balance after any down payment. If a home costs $375,000 and the down payment is $75,000, that loan amount follows by subtraction. Entering the full home price would calculate a larger loan and a different payment. The form does not subtract a down payment a second time.
Comparing a shorter term
Keeping the same $300,000 balance and 6% rate but choosing 15 years gives 180 monthly payments. Principal and interest is approximately $2,531.57 per month. The monthly payment rises, but scheduled interest falls to approximately $155,682.14. This is a comparison with the same assumed rate; actual offers for different terms can have different rates and fees.
Do not judge affordability from the lower lifetime interest alone. A larger monthly commitment can affect cash flow, and the calculator does not know your other obligations. Compare full written loan offers under consistent assumptions, including costs excluded from this simplified model.
Checking the zero-rate branch
A $120,000 balance at 0% over ten years is repaid through 120 payments of $1,000 before tax or insurance. Scheduled interest is zero. This is a mathematical check of the amortization formula, not a claim that such a mortgage is available. Adding $2,400 annual tax and $1,200 annual insurance would raise the monthly estimate to $1,300 without creating loan interest.
When to use this estimate, and when not to
Use it to compare fixed-rate scenarios, understand a payment breakdown or check how term length changes the scheduled payment. Change one input at a time so the comparison remains interpretable. Keep the loan amount, rate, term and entered annual costs with any saved result.
Do not use it to establish loan eligibility, choose an investment, calculate a binding payoff or replace a Loan Estimate. It does not include closing costs, escrow shortages, mortgage insurance, association dues, maintenance, utilities, extra principal payments or missed payments. A monthly figure without those costs is only one part of a household budget. Verify the terms and totals with the lender before making a financial commitment.
FAQ
Is APR the rate I should enter?
Use the nominal note rate for this monthly amortization formula. APR serves a broader comparison purpose and may include certain fees. Substituting it can change the payment estimate without correctly modeling those fees. Check the loan documents if the two rates differ or the offer does not clearly identify the note rate.
Does the result include the down payment?
No. Enter the loan amount after subtracting the down payment from the financed purchase amount. The down payment is an upfront contribution, not part of the scheduled monthly principal-and-interest payment here. Closing costs financed into the balance need to be reflected in the entered loan amount if applicable.
Why can my actual monthly bill change on a fixed-rate loan?
The fixed part is generally principal and interest under the assumed schedule. Property taxes, insurance and escrow adjustments can change. This tool spreads your entered annual costs evenly across twelve months; it does not forecast future assessments or premiums. Compare the individual components on a mortgage statement rather than only the total.
Are PMI and HOA included?
No. They are excluded and are not estimated from your down payment or location. If either applies, add the appropriate amount separately when reviewing a budget. The absence of a field does not mean the charge is zero or that a particular loan avoids mortgage insurance.
Can I model additional monthly principal payments?
This version assumes only the scheduled payment. Extra principal changes the balance path and payoff date, so subtracting an arbitrary amount from total interest would be incorrect. Use an amortization model that explicitly applies extra payments and verify any prepayment conditions in the loan documents.
Related tools and guides
For reference only. This page does not provide financial advice, a loan offer or a guarantee of borrowing terms.