Retaining Wall Cost Calculator

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Mortgage Monthly Payment Calculator

30 Years 20 Years 15 Years 10 Years
Estimated Monthly Payment: $0.00
Total Principal: $0.00
Total Interest Paid: $0.00
Total Cost of Loan: $0.00
function calculateMortgage() { var homePrice = parseFloat(document.getElementById('homePrice').value); var downPayment = parseFloat(document.getElementById('downPayment').value); var annualRate = parseFloat(document.getElementById('interestRate').value); var years = parseInt(document.getElementById('loanTerm').value); if (isNaN(homePrice) || isNaN(downPayment) || isNaN(annualRate) || isNaN(years) || homePrice <= 0) { alert("Please enter valid positive numbers for all fields."); return; } var principal = homePrice – downPayment; if (principal <= 0) { alert("Down payment cannot be greater than or equal to the home price."); return; } var monthlyRate = (annualRate / 100) / 12; var numberOfPayments = years * 12; var monthlyPayment = 0; if (monthlyRate === 0) { monthlyPayment = principal / numberOfPayments; } else { monthlyPayment = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1); } var totalCost = monthlyPayment * numberOfPayments; var totalInterest = totalCost – principal; document.getElementById('monthlyResult').innerText = '$' + monthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('principalResult').innerText = '$' + principal.toLocaleString(); document.getElementById('interestTotalResult').innerText = '$' + totalInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('totalCostResult').innerText = '$' + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('mortgageResult').style.display = 'block'; }

How Your Monthly Mortgage Payment is Calculated

Purchasing a home is one of the most significant financial decisions you will ever make. Understanding the components of your monthly mortgage payment helps you budget effectively and select the right loan term for your financial goals.

The Principal and Interest (P&I) Formula

The core of your mortgage payment is the Principal and Interest. This calculator uses the standard amortization formula:

M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
  • P (Principal): The total amount of money you borrow (Home Price minus Down Payment).
  • i (Monthly Interest Rate): Your annual interest rate divided by 12.
  • n (Number of Months): The total number of payments (e.g., 30 years = 360 payments).

Realistic Example: The Impact of Interest

Consider a $400,000 home with a 20% down payment ($80,000). You are borrowing $320,000.

Rate Term Monthly P&I Total Interest
6.5% 30 Years $2,022.62 $408,144
4.5% 30 Years $1,621.39 $263,700

What Else Is Included in a Mortgage Payment?

While this calculator focuses on the loan repayment (P&I), remember that your actual "all-in" monthly cost usually includes PITI:

  1. Principal: The repayment of the borrowed amount.
  2. Interest: The cost paid to the lender for the loan.
  3. Taxes: Property taxes assessed by your local government.
  4. Insurance: Homeowners insurance and potentially Private Mortgage Insurance (PMI) if your down payment is less than 20%.

Tips to Lower Your Monthly Payment

If the calculated result is higher than your budget, consider these strategies:

  • Increase your Down Payment: Borrowing less reduces the principal and may eliminate the need for PMI.
  • Improve your Credit Score: Higher scores qualify for lower interest rates, which significantly impact the monthly payment.
  • Compare Loan Terms: A 15-year mortgage has higher monthly payments but saves you tens of thousands in interest over the life of the loan.
  • Shop Multiple Lenders: Even a 0.25% difference in interest rate can save you $50-$100 every single month.

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