Rental Property Cash Flow Calculator
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Monthly Cash Flow
$0.00
Monthly Income
$0.00
Monthly Expenses
$0.00
Mortgage Payment
$0.00
Net Operating Income (NOI)
$0.00
Cash on Cash Return
0.00%
Understanding Rental Property Cash Flow
Investing in real estate is a powerful way to build wealth, but the key to a successful investment lies in understanding the numbers. This Rental Property Cash Flow Calculator is designed to help investors evaluate the profitability of a potential purchase by breaking down income, operating expenses, and debt service.
What is Cash Flow?
Cash flow is the net amount of cash moving into or out of an investment. In real estate terms, it is the money remaining after all bills—including the mortgage, taxes, insurance, and maintenance—have been paid. A property with positive cash flow puts money in your pocket every month, while a property with negative cash flow requires you to pay out of pocket to keep it running.
Key Metrics Explained
- Net Operating Income (NOI): This is your total income minus operating expenses (excluding the mortgage). It is a pure measure of the property's efficiency.
- Cash on Cash Return (CoC): This metric compares your annual pre-tax cash flow to the total cash invested (down payment + closing costs). It is one of the most important ROI metrics for real estate investors.
- Vacancy Rate: No property is occupied 100% of the time. We include a vacancy rate allowance (typically 5-10%) to account for turnover periods where no rent is collected.
How to Use This Calculator
To get an accurate estimate of your potential returns, input the purchase price and loan details first. Be realistic with your expense estimates. While mortgage payments are fixed, costs like maintenance and vacancy are variable. It is generally safer to overestimate expenses than to underestimate them.
Interpreting Your Results
If your Monthly Cash Flow is green, the property generates profit. If it is red, the property costs more to hold than it generates in rent. While some investors rely on appreciation (the property increasing in value over time), relying solely on appreciation is risky. Seasoned investors typically look for positive cash flow to ensure the asset is self-sustaining.
function calculateCashFlow() {
// 1. Get Input Values
var purchasePrice = parseFloat(document.getElementById('purchasePrice').value);
var downPaymentPercent = parseFloat(document.getElementById('downPaymentPercent').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var monthlyRent = parseFloat(document.getElementById('monthlyRent').value);
var annualPropertyTax = parseFloat(document.getElementById('propertyTax').value);
var annualInsurance = parseFloat(document.getElementById('insurance').value);
var monthlyHOA = parseFloat(document.getElementById('hoaFees').value);
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value);
var maintenanceRate = parseFloat(document.getElementById('maintenanceRate').value);
// Validation
if (isNaN(purchasePrice) || isNaN(monthlyRent)) {
alert("Please enter valid numbers for Price and Rent.");
return;
}
// 2. Calculate Mortgage Details
var downPaymentAmount = purchasePrice * (downPaymentPercent / 100);
var loanAmount = purchasePrice – downPaymentAmount;
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var monthlyMortgage = 0;
if (interestRate === 0) {
monthlyMortgage = loanAmount / numberOfPayments;
} else {
monthlyMortgage = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
// 3. Calculate Monthly Operating Expenses
var monthlyTax = annualPropertyTax / 12;
var monthlyInsurance = annualInsurance / 12;
var vacancyCost = monthlyRent * (vacancyRate / 100);
var maintenanceCost = monthlyRent * (maintenanceRate / 100);
var totalOperatingExpenses = monthlyTax + monthlyInsurance + monthlyHOA + vacancyCost + maintenanceCost;
var totalMonthlyExpenses = totalOperatingExpenses + monthlyMortgage;
// 4. Calculate Key Metrics
var noi = monthlyRent – totalOperatingExpenses;
var monthlyCashFlow = monthlyRent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
// Assume closing costs are roughly 2% of purchase price for CoC calculation estimation if not specified
// For this specific calculator, we will base CoC on Down Payment to keep inputs simple but accurate to user input
var totalCashInvested = downPaymentAmount;
var cashOnCashReturn = 0;
if (totalCashInvested > 0) {
cashOnCashReturn = (annualCashFlow / totalCashInvested) * 100;
}
// 5. Update UI
// Helper function for formatting currency
function formatMoney(num) {
return '$' + num.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
}
document.getElementById('monthlyCashFlow').innerText = formatMoney(monthlyCashFlow);
document.getElementById('resultIncome').innerText = formatMoney(monthlyRent);
document.getElementById('resultExpenses').innerText = formatMoney(totalMonthlyExpenses);
document.getElementById('resultMortgage').innerText = formatMoney(monthlyMortgage);
document.getElementById('resultNOI').innerText = formatMoney(noi);
document.getElementById('resultCoC').innerText = cashOnCashReturn.toFixed(2) + '%';
// Styling for positive/negative cash flow
var resultBox = document.getElementById('cashFlowResultBox');
if (monthlyCashFlow >= 0) {
resultBox.classList.remove('negative');
} else {
resultBox.classList.add('negative');
}
}
// Run calculation on load
window.onload = function() {
calculateCashFlow();
};