Analyze the profitability of your potential real estate investment.
Principal & Interest (Mortgage)$0.00
Total Monthly Expenses$0.00
Net Operating Income (Monthly)$0.00
Net Monthly Cash Flow$0.00
Cash on Cash ROI0.00%
function calculateRentalCashFlow() {
// 1. Get Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPct = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var tax = parseFloat(document.getElementById('annualTax').value);
var insurance = parseFloat(document.getElementById('annualInsurance').value);
var hoa = parseFloat(document.getElementById('monthlyHOA').value);
// Validate inputs
if (isNaN(price) || isNaN(rent) || isNaN(rate) || isNaN(term)) {
alert("Please enter valid numbers for all fields.");
return;
}
// 2. Calculate Mortgage
var downPaymentAmount = price * (downPct / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = (rate / 100) / 12;
var numberOfPayments = term * 12;
var mortgagePayment = 0;
if (rate === 0) {
mortgagePayment = loanAmount / numberOfPayments;
} else {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// 3. Calculate Expenses
var monthlyTax = tax / 12;
var monthlyInsurance = insurance / 12;
var totalMonthlyExpenses = mortgagePayment + monthlyTax + monthlyInsurance + hoa;
// 4. Calculate Cash Flow
var cashFlow = rent – totalMonthlyExpenses;
var annualCashFlow = cashFlow * 12;
// 5. Calculate ROI (Cash on Cash)
// Assuming simple closing costs as 3% of price for realistic ROI estimation, or just Down Payment.
// For this calculator, we will use Down Payment as the "Cash Invested" to keep it standard.
var cashInvested = downPaymentAmount;
var roi = 0;
if (cashInvested > 0) {
roi = (annualCashFlow / cashInvested) * 100;
}
// 6. Update UI
// Format currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('resMortgage').innerText = formatter.format(mortgagePayment);
document.getElementById('resTotalExpenses').innerText = formatter.format(totalMonthlyExpenses);
// Net Operating Income (Rent – Operating Expenses excluding Debt Service)
// Note: Standard NOI excludes mortgage. But often people want "Cash Flow" vs "NOI".
// For this simple view, we will just show the Cash Flow breakdown.
// Let's calculate standard NOI for the "Net Operating Income" label: Rent – (Tax + Ins + HOA).
var operatingExpenses = monthlyTax + monthlyInsurance + hoa;
var noi = rent – operatingExpenses;
document.getElementById('resNOI').innerText = formatter.format(noi);
// Cash Flow
var cfElement = document.getElementById('resCashFlow');
cfElement.innerText = formatter.format(cashFlow);
if(cashFlow >= 0) {
cfElement.style.color = "#27ae60";
} else {
cfElement.style.color = "#e74c3c";
}
// ROI
var roiElement = document.getElementById('resROI');
roiElement.innerText = roi.toFixed(2) + "%";
if(roi >= 0) {
roiElement.style.color = "#2c3e50";
} else {
roiElement.style.color = "#e74c3c";
}
// Show results
document.getElementById('resultsArea').style.display = "block";
}
Understanding Rental Property Cash Flow
Investing in real estate is one of the most reliable ways to build wealth, but simply buying a property and renting it out doesn't guarantee a profit. To succeed, you must understand the numbers behind the investment. This Rental Property Cash Flow Calculator helps you analyze whether a potential deal will put money in your pocket (positive cash flow) or take it out (negative cash flow).
What is Cash Flow?
Cash flow is the net amount of money moving in and out of your rental business. In simple terms, it is the money left over from your monthly rental income after all expenses—including your mortgage, taxes, insurance, and maintenance—have been paid.
Positive Cash Flow: Your income exceeds your expenses. This is the goal of most buy-and-hold investors.
Negative Cash Flow: Your expenses exceed your income. You are losing money every month to hold the property.
Key Metrics in This Calculator
Net Operating Income (NOI): This is your annual rental income minus operating expenses (taxes, insurance, HOA, maintenance), excluding mortgage payments. It measures the profitability of the property itself, regardless of financing.
Cash on Cash Return (ROI): This percentage measures the return on the actual cash you invested (down payment). It allows you to compare real estate returns against other investments like stocks or bonds.
Debt Service: This is your monthly mortgage payment (Principal and Interest). It is usually the largest expense for real estate investors using leverage.
How to Improve Your Cash Flow
If your calculation shows negative or low cash flow, consider these strategies:
Increase Rent: Research local market rates. Are you charging enough? Can small renovations justify a higher rent?
Lower Expenses: Shop around for cheaper insurance, appeal your property tax assessment, or manage the property yourself to save on management fees.
Increase Down Payment: Putting more money down reduces your loan amount and monthly mortgage payment, instantly boosting monthly cash flow.
Is the 1% Rule Still Valid?
A common rule of thumb in real estate is the "1% Rule," which suggests that the monthly rent should be at least 1% of the purchase price. For example, a $200,000 home should rent for $2,000/month. While this is a quick screening tool, our calculator provides a much more accurate financial picture by factoring in interest rates, taxes, and specific HOA fees.