Calculate your potential monthly profit, Cap Rate, and ROI on a real estate investment.
Monthly Mortgage (P&I):
Total Monthly Operating Expenses:
Net Monthly Cash Flow:
Capitalization Rate (Cap Rate):
Annual Cash-on-Cash Return:
function calculateRentalROI() {
var price = parseFloat(document.getElementById('propPrice').value);
var downPct = parseFloat(document.getElementById('downPayment').value) / 100;
var rate = parseFloat(document.getElementById('interestRate').value) / 100 / 12;
var term = parseFloat(document.getElementById('loanTerm').value) * 12;
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxes = parseFloat(document.getElementById('annualTaxes').value) / 12;
var insurance = parseFloat(document.getElementById('annualInsurance').value) / 12;
var maintPct = parseFloat(document.getElementById('maintenancePercent').value) / 100;
if (isNaN(price) || isNaN(rent) || price 0) {
monthlyMortgage = principal * (rate * Math.pow(1 + rate, term)) / (Math.pow(1 + rate, term) – 1);
} else {
monthlyMortgage = principal / term;
}
// Operating Expenses
var maintenance = rent * maintPct;
var totalOperatingExpenses = taxes + insurance + maintenance;
var totalMonthlyOutlay = totalOperatingExpenses + monthlyMortgage;
// Cash Flow
var monthlyCashFlow = rent – totalMonthlyOutlay;
var annualNetOperatingIncome = (rent – totalOperatingExpenses) * 12;
// Metrics
var capRate = (annualNetOperatingIncome / price) * 100;
var cashOnCash = ((monthlyCashFlow * 12) / downAmount) * 100;
// Display
document.getElementById('resMortgage').innerText = "$" + monthlyMortgage.toFixed(2);
document.getElementById('resExpenses').innerText = "$" + (totalOperatingExpenses).toFixed(2);
document.getElementById('resCashFlow').innerText = "$" + monthlyCashFlow.toFixed(2);
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('resCoC').innerText = cashOnCash.toFixed(2) + "%";
// Styling logic
var cashFlowEl = document.getElementById('resCashFlow');
if (monthlyCashFlow > 0) {
cashFlowEl.className = "result-value positive";
} else {
cashFlowEl.className = "result-value negative";
}
document.getElementById('resultsArea').style.display = 'block';
}
Understanding Rental Property Cash Flow
Investing in real estate is one of the most proven ways to build long-term wealth. However, the difference between a "good deal" and a "money pit" often comes down to one metric: Cash Flow. This calculator helps you look beyond the monthly rent and see the true profitability of a rental property.
What is Monthly Cash Flow?
Monthly cash flow is the amount of money left over from your rental income after all expenses have been paid. These expenses include your mortgage payment, property taxes, insurance, and a buffer for maintenance and vacancies.
To evaluate a property properly, you need to understand these two critical metrics:
Cap Rate (Capitalization Rate): This measures the property's natural rate of return without considering financing. It's calculated by taking the Net Operating Income (NOI) divided by the purchase price. A cap rate of 5% to 10% is often considered healthy in many markets.
Cash-on-Cash Return (CoC): This measures the return on the actual cash you invested (your down payment). Since real estate allows for leverage (mortgages), your CoC return is often higher than your Cap Rate. This is how investors build wealth quickly.
Why Maintenance and Vacancy Reserves Matter
One of the biggest mistakes new landlords make is failing to account for maintenance and vacancy. No tenant stays forever, and every roof eventually leaks. By setting aside 10% of the rent each month in your calculations, you ensure that your investment stays "in the black" even when unexpected repairs arise.
Example Calculation
Imagine you buy a property for $250,000 with 20% down ($50,000).
If your rent is $2,200 and your total monthly expenses (including mortgage) are $1,850,
your monthly cash flow is $350.
Your annual cash flow would be $4,200, resulting in an 8.4% Cash-on-Cash return ($4,200 / $50,000).