Interest Rate Accumulation Calculator

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Rental Property ROI & Cash Flow Calculator

Investment Summary

Monthly Cash Flow:

Cap Rate:

Cash on Cash Return:

Total Monthly Expenses:

function calculateRentalROI() { var price = parseFloat(document.getElementById('purchasePrice').value); var downPercent = parseFloat(document.getElementById('downPaymentPercent').value); var rate = parseFloat(document.getElementById('interestRate').value) / 100 / 12; var rent = parseFloat(document.getElementById('monthlyRent').value); var tax = parseFloat(document.getElementById('propertyTax').value) / 12; var ins = parseFloat(document.getElementById('insurance').value) / 12; if (isNaN(price) || isNaN(rent)) { alert("Please enter valid numbers"); return; } var downPayment = price * (downPercent / 100); var loanAmount = price – downPayment; var months = 30 * 12; // Mortgage Calculation (P&I) var monthlyMortgage = 0; if (rate > 0) { monthlyMortgage = loanAmount * (rate * Math.pow(1 + rate, months)) / (Math.pow(1 + rate, months) – 1); } else { monthlyMortgage = loanAmount / months; } // Operating Expenses (Maintenance estimated at 1% of price annually) var maintenance = (price * 0.01) / 12; var totalMonthlyExpenses = monthlyMortgage + tax + ins + maintenance; var monthlyCashFlow = rent – totalMonthlyExpenses; // Annual Metrics var annualNetOperatingIncome = (rent * 12) – ((tax + ins + maintenance) * 12); var capRate = (annualNetOperatingIncome / price) * 100; var cashOnCash = ((monthlyCashFlow * 12) / downPayment) * 100; // Display results document.getElementById('results-box').style.display = 'block'; document.getElementById('resCashFlow').innerText = '$' + monthlyCashFlow.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resCapRate').innerText = capRate.toFixed(2) + '%'; document.getElementById('resCOC').innerText = cashOnCash.toFixed(2) + '%'; document.getElementById('resExpenses').innerText = '$' + totalMonthlyExpenses.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); }

Understanding Your Rental Property ROI

Investing in real estate is one of the most proven ways to build long-term wealth, but the math must work before you sign the closing papers. Our Rental Property ROI Calculator helps you peel back the layers of a property's financial potential by looking at cash flow, capitalization rates, and cash-on-cash returns.

Key Metrics Explained

  • Monthly Cash Flow: This is the net profit you take home every month after all expenses—including the mortgage, taxes, insurance, and maintenance—have been paid. Positive cash flow is vital for sustaining an investment.
  • Cap Rate (Capitalization Rate): This represents the natural rate of return for a property without considering financing. It is calculated by dividing the Net Operating Income (NOI) by the purchase price.
  • Cash on Cash (CoC) Return: This is often considered the most important metric for investors using leverage. It measures the annual cash flow relative to the actual amount of "out-of-pocket" cash invested (your down payment).

Example Calculation

Imagine you purchase a duplex for $300,000 with a 20% down payment ($60,000). If your total monthly expenses (mortgage, tax, insurance) are $1,900 and the total rent collected is $2,500, your monthly cash flow is $600.

Your annual cash flow would be $7,200 ($600 x 12). To find your Cash on Cash return: ($7,200 / $60,000) * 100 = 12%. This means you are earning a 12% annual return on the cash you physically moved from your bank account into the deal.

Factors That Impact Your ROI

While this calculator provides a solid baseline, remember to account for vacancy rates (usually 5-10% of gross rent) and property management fees (typically 8-12% of monthly rent) if you aren't managing the property yourself. Consistent maintenance reserves (1% of the property value per year) are also critical to ensure a single broken HVAC system doesn't wipe out your entire year of profit.

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