Simple Mortgage Calculator

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simple mortgage calculator
Calculate Monthly PaymentCalculate Loan Principal
Result:

Estimated Monthly Payment = $ 0.00

function calculateResult(){var price=parseFloat(document.getElementById('input1').value);var down=parseFloat(document.getElementById('input2').value);var rate=parseFloat(document.getElementById('input3').value);var years=parseFloat(document.getElementById('input4').value);if(isNaN(price)||isNaN(down)||isNaN(rate)||isNaN(years)){alert('Please enter valid numeric values in all fields.');return;}var principal=price-down;if(principal<=0){alert('Down payment cannot be greater than or equal to home price.');return;}var monthlyRate=rate/100/12;var numberOfPayments=years*12;var monthlyPayment=principal*(monthlyRate*Math.pow(1+monthlyRate,numberOfPayments))/(Math.pow(1+monthlyRate,numberOfPayments)-1);var totalPaid=monthlyPayment*numberOfPayments;var totalInterest=totalPaid-principal;document.getElementById('resultValue').innerHTML=monthlyPayment.toLocaleString(undefined,{minimumFractionDigits:2,maximumFractionDigits:2});if(document.getElementById('steps').checked){document.getElementById('breakdown').innerHTML='Total Principal: $'+principal.toLocaleString()+'
Total Interest: $'+totalInterest.toLocaleString(undefined,{maximumFractionDigits:2})+'
Total Cost of Loan: $'+totalPaid.toLocaleString(undefined,{maximumFractionDigits:2});}else{document.getElementById('breakdown').innerHTML=";}document.getElementById('answer').style.display='block';}

Calculator Use

This simple mortgage calculator is designed to help prospective homebuyers quickly estimate their monthly principal and interest payments. By adjusting key variables such as the home purchase price, down payment amount, and current interest rates, you can gain a clear understanding of your financial commitment before starting the home-buying process.

Whether you are a first-time homebuyer or looking to refinance, understanding your monthly costs is essential for maintaining a healthy budget. This tool simplifies complex financial math into an easy-to-read result.

Home Price
The total purchase price of the property you intend to buy.
Down Payment
The initial cash payment you make upfront. This is subtracted from the Home Price to determine the loan principal.
Interest Rate
The annual interest percentage charged by the lender on the borrowed amount.
Loan Term
The duration of the mortgage, typically 15 or 30 years, over which the loan will be repaid.

How It Works

The simple mortgage calculator utilizes the standard amortization formula to calculate the monthly payment (M). The calculation takes into account the reduction of the principal balance over time while accounting for interest charges. The mathematical formula is as follows:

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

  • M: Total monthly payment.
  • P: Principal loan amount (Home Price – Down Payment).
  • i: Monthly interest rate (Annual Rate / 12).
  • n: Total number of monthly payments (Years * 12).

Calculation Example

Example: Imagine you are purchasing a home for $400,000 with a $80,000 down payment. You secured a 30-year fixed-rate mortgage at an interest rate of 7%.

Step-by-step solution:

  1. Calculate Principal (P): $400,000 – $80,000 = $320,000.
  2. Calculate Monthly Interest (i): 7% / 100 / 12 = 0.005833.
  3. Calculate Number of Payments (n): 30 years * 12 months = 360 payments.
  4. Apply Formula: M = 320,000 [ 0.005833(1 + 0.005833)^360 ] / [ (1 + 0.005833)^360 – 1 ]
  5. Result: Monthly Payment = $2,128.97

Common Questions

Does this include taxes and insurance?

No, this simple mortgage calculator only computes the Principal and Interest (P&I) portion of your payment. In reality, your monthly "PITI" payment will also include Property Taxes and Homeowners Insurance, which vary by location.

Why does the down payment matter so much?

The more money you put down, the less you need to borrow. A smaller loan principal results in lower interest charges over the life of the loan. Additionally, a down payment of 20% or more usually allows you to avoid Private Mortgage Insurance (PMI).

How does the term length affect my payment?

A shorter term (like 15 years) will have higher monthly payments because you are paying off the principal faster, but you will pay significantly less in total interest over the life of the loan compared to a 30-year mortgage.

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