Rental Property Cash Flow Calculator
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Financial Performance
Monthly Cash Flow
$0.00
Annual: $0.00
Cash on Cash ROI
0.00%
Total Cash Invested: $0.00
Cap Rate
0.00%
Net Operating Income: $0.00
Monthly Expense Breakdown
Mortgage (P&I): $0.00
Taxes & Ins: $0.00
Vacancy & Maint: $0.00
Total Expenses: $0.00
Understanding Rental Property Cash Flow Analysis
Investing in real estate is one of the most reliable ways to build wealth, but the difference between a profitable asset and a financial liability often comes down to the numbers. Using a Rental Property Cash Flow Calculator is essential for investors to evaluate the potential return on investment (ROI) before signing a contract.
What is Cash Flow?
Cash flow is the net amount of money moving into and out of a business or investment. In real estate, positive cash flow occurs when a property's gross rental income exceeds all expenses, including the mortgage, taxes, insurance, and operating costs. This is the "passive income" investors seek.
Key Metrics Explained
- Net Operating Income (NOI): This is the total income the property generates minus all necessary operating expenses. Importantly, NOI excludes mortgage payments. It is a pure measure of the property's efficiency.
- Cash on Cash ROI: This metric compares the annual pre-tax cash flow to the total amount of cash invested (down payment + closing costs + rehab costs). It tells you how hard your actual dollars are working for you. A CoC ROI of 8-12% is generally considered good in many markets.
- Cap Rate (Capitalization Rate): Calculated as NOI divided by the property's purchase price. This helps compare the profitability of similar properties regardless of how they are financed (cash vs. loan).
Estimating Expenses Correctly
New investors often make the mistake of only calculating the mortgage payment. To get an accurate picture, you must account for:
- Vacancy: Properties won't be rented 365 days a year. A 5-8% vacancy allowance is standard.
- Maintenance: Roofs leak and toilets break. Setting aside 5-10% of monthly rent ensures you have funds for repairs.
- CapEx (Capital Expenditures): Major replacements like HVAC or water heaters should be budgeted for separately from general maintenance.
Use the calculator above to adjust these variables and stress-test your investment. What happens if the rent drops by $100? What if interest rates rise? Running these scenarios will help you make a confident, data-driven investment decision.
function calculateRentalROI() {
// 1. Get Inputs
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var closingCosts = parseFloat(document.getElementById('closingCosts').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var monthlyRent = parseFloat(document.getElementById('rentalIncome').value);
var annualTax = parseFloat(document.getElementById('propertyTax').value);
var annualIns = parseFloat(document.getElementById('insurance').value);
var vacancyRate = parseFloat(document.getElementById('vacancyRate').value);
var maintenanceRate = parseFloat(document.getElementById('maintenanceRate').value);
// Validation
if (isNaN(price) || isNaN(downPayment) || isNaN(interestRate) || isNaN(monthlyRent)) {
document.getElementById('errorMsg').style.display = 'block';
return;
} else {
document.getElementById('errorMsg').style.display = 'none';
}
// 2. Mortgage Calculation (Principal & Interest)
var loanAmount = price – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var mortgagePayment = 0;
if (loanAmount > 0) {
if (interestRate === 0) {
mortgagePayment = loanAmount / numberOfPayments;
} else {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
}
// 3. Expense Calculations
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var monthlyVacancy = monthlyRent * (vacancyRate / 100);
var monthlyMaintenance = monthlyRent * (maintenanceRate / 100);
var totalMonthlyExpenses = mortgagePayment + monthlyTax + monthlyIns + monthlyVacancy + monthlyMaintenance;
var operatingExpenses = monthlyTax + monthlyIns + monthlyVacancy + monthlyMaintenance; // For NOI
// 4. Income Metrics
var monthlyCashFlow = monthlyRent – totalMonthlyExpenses;
var annualCashFlow = monthlyCashFlow * 12;
var annualNOI = (monthlyRent * 12) – (operatingExpenses * 12);
// 5. ROI Metrics
var totalCashInvested = downPayment + closingCosts;
var cashOnCashRoi = 0;
if (totalCashInvested > 0) {
cashOnCashRoi = (annualCashFlow / totalCashInvested) * 100;
}
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
// 6. Formatting & Display
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
document.getElementById('monthlyCashFlow').innerHTML = formatter.format(monthlyCashFlow);
document.getElementById('monthlyCashFlow').style.color = monthlyCashFlow >= 0 ? '#27ae60' : '#e74c3c';
document.getElementById('annualCashFlow').innerHTML = 'Annual: ' + formatter.format(annualCashFlow);
document.getElementById('cocRoi').innerHTML = cashOnCashRoi.toFixed(2) + '%';
document.getElementById('cocRoi').style.color = cashOnCashRoi >= 0 ? '#27ae60' : '#e74c3c';
document.getElementById('totalInvested').innerHTML = formatter.format(totalCashInvested);
document.getElementById('capRate').innerHTML = capRate.toFixed(2) + '%';
document.getElementById('noiAnnual').innerHTML = formatter.format(annualNOI);
// Expense Breakdown
document.getElementById('mortgagePayment').innerHTML = formatter.format(mortgagePayment);
document.getElementById('taxInsPayment').innerHTML = formatter.format(monthlyTax + monthlyIns);
document.getElementById('opsPayment').innerHTML = formatter.format(monthlyVacancy + monthlyMaintenance);
document.getElementById('totalExpenses').innerHTML = formatter.format(totalMonthlyExpenses);
}
// Initialize on load
window.onload = function() {
calculateRentalROI();
};