Mortgage Payment Calculator

by
mortgage payment calculator
Calculate Monthly Payment (P & I)Calculate Loan Amount (Principal)
Summary:
Enter details and click Calculate
function toggleInputs(){var mode=document.getElementById('given_data').value;var l1=document.getElementById('label1');var l4=document.getElementById('label4');var r4=document.getElementById('row4′);if(mode==='principal'){l1.innerHTML='Monthly Payment: $';l4.innerHTML='Down Payment: $';r4.style.display='none';}else{l1.innerHTML='Home Price: $';l4.innerHTML='Down Payment: $';r4.style.display='table-row';}}function calculateMortgage(){var mode=document.getElementById('given_data').value;var v1=parseFloat(document.getElementById('input1').value);var v2=parseFloat(document.getElementById('input2').value);var v3=parseFloat(document.getElementById('input3').value);var v4=parseFloat(document.getElementById('input4').value || 0);var includeEscrow=document.getElementById('steps').checked;if(isNaN(v1)||isNaN(v2)||isNaN(v3)){alert('Please enter valid numeric values');return;}var annualRate=v2/100;var monthlyRate=annualRate/12;var months=v3*12;if(mode==='payment'){var principal=v1-v4;if(principal<=0){alert('Down payment cannot exceed home price');return;}var payment=principal*(monthlyRate*Math.pow(1+monthlyRate,months))/(Math.pow(1+monthlyRate,months)-1);var tax=includeEscrow ? (v1*0.012)/12 : 0;var ins=includeEscrow ? (v1*0.0035)/12 : 0;var total=payment+tax+ins;document.getElementById('resText').innerHTML='Estimated Monthly Payment';document.getElementById('resultDisplay').innerHTML='$'+total.toLocaleString(undefined,{minimumFractionDigits:2,maximumFractionDigits:2});document.getElementById('breakdown').innerHTML='Principal & Interest: $'+payment.toLocaleString(undefined,{maximumFractionDigits:2})+(includeEscrow ? '
Estimated Tax & Insurance: $'+(tax+ins).toLocaleString(undefined,{maximumFractionDigits:2}) : ");}else{var payment=v1;var principal=payment*((Math.pow(1+monthlyRate,months)-1)/(monthlyRate*Math.pow(1+monthlyRate,months)));document.getElementById('resText').innerHTML='Maximum Loan Amount';document.getElementById('resultDisplay').innerHTML='$'+principal.toLocaleString(undefined,{minimumFractionDigits:2,maximumFractionDigits:2});document.getElementById('breakdown').innerHTML='Based on a $'+payment+' monthly budget at '+v2+'% interest.';}}

Calculator Use

This mortgage payment calculator is designed to help prospective homebuyers and homeowners estimate their monthly financial obligations. By entering the purchase price, down payment, interest rate, and term, you can instantly see how much your monthly principal and interest payment will be. This tool is essential for budgeting and determining how much house you can truly afford.

Whether you are looking at a 30-year fixed-rate mortgage or a shorter 15-year term, this calculator provides a clear breakdown of costs.

Home Price
The total purchase price of the property you intend to buy.
Down Payment
The initial cash payment made upfront, usually expressed as a dollar amount. This reduces the total loan principal.
Interest Rate
The annual interest percentage charged by the lender for the loan.
Loan Term
The number of years you have to repay the loan (commonly 15, 20, or 30 years).

How It Works

The calculator uses the standard amortization formula to determine the monthly payment required to pay off the loan balance by the end of the term. The formula for the monthly payment (M) is:

M = P [ r(1 + r)^n ] / [ (1 + r)^n – 1 ]

  • M: Total monthly payment (Principal + Interest).
  • P: Principal loan amount (Home Price minus Down Payment).
  • r: Monthly interest rate (Annual Rate divided by 12 months).
  • n: Total number of monthly payments (Years multiplied by 12).

Calculation Example

Example: Suppose you want to buy a home for $400,000 with a $80,000 down payment. You secure a 30-year fixed mortgage at an interest rate of 6%.

Step-by-step solution:

  1. Calculate Principal: $400,000 – $80,000 = $320,000
  2. Monthly Interest Rate: 0.06 / 12 = 0.005
  3. Number of Payments: 30 * 12 = 360
  4. Apply Formula: M = 320,000 [ 0.005(1 + 0.005)^360 ] / [ (1 + 0.005)^360 – 1 ]
  5. Calculate: M = 320,000 [ 0.005 * 6.02257 ] / [ 5.02257 ]
  6. Result = $1,918.56 per month

Common Questions

Does the payment include taxes?

Standard mortgage payment formulas only calculate Principal and Interest (P&I). However, many homeowners must also pay property taxes, homeowners insurance, and sometimes private mortgage insurance (PMI). If you check the "Include property taxes and insurance" box, our calculator adds estimated national averages for these costs.

What is a good down payment?

While 20% is the traditional benchmark to avoid PMI, many modern loan programs allow for as little as 3% or 3.5% down (and 0% for VA loans). A larger down payment reduces your monthly payment and interest paid over the life of the loan.

How does interest rate affect the total cost?

Even a 1% difference in interest rate can result in tens of thousands of dollars in savings or costs over 30 years. Using this mortgage payment calculator to compare different rates from lenders is one of the smartest steps you can take before signing a contract.

Leave a Comment