Rental Property Cash Flow Calculator
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Cash on Cash Return (CoC)
0.00%
Understanding Rental Property Cash Flow
Cash flow is the lifeblood of any rental property investment. It represents the net amount of cash moving into or out of a business or investment. For real estate investors, calculating accurate cash flow is critical to determining whether a property is a viable asset or a financial liability.
Key Formula:
Cash Flow = Total Monthly Income – Total Monthly Expenses (including mortgage)
How to Use This Calculator
This tool breaks down the complex mathematics of real estate investment into simple inputs. Here is what you need to know about the key metrics:
- NOI (Net Operating Income): This is your annual income minus operating expenses, excluding mortgage payments. It measures the raw profitability of the property itself.
- Cap Rate (Capitalization Rate): Calculated as NOI divided by the property price. It helps compare the profitability of different properties regardless of how they are financed.
- Cash on Cash Return (CoC): This is perhaps the most important metric for leveraged investors. It calculates the annual cash flow divided by the total cash you actually invested (down payment + closing costs).
Common Expenses Landlords Overlook
When estimating cash flow, beginners often calculate Mortgage, Taxes, and Insurance (PITI) but forget the "silent killers" of profitability:
- Vacancy Rate: Properties are rarely occupied 100% of the time. A standard conservative estimate is 5-8% (about 2-3 weeks of vacancy per year).
- Maintenance & CapEx: Roofs leak and toilets break. Setting aside 5-10% of rent for repairs is prudent.
- Property Management: Even if you self-manage now, calculating a 10% management fee ensures the deal still works if you decide to hire a professional later.
Interpreting Your Results
Positive Cash Flow: The property pays for itself and generates profit. This is the goal for buy-and-hold investors.
Negative Cash Flow: You must contribute money every month to keep the property. This might be acceptable in high-appreciation markets, but it carries higher risk.
function calculateRentalCashFlow() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPercent = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
var closing = parseFloat(document.getElementById('closingCosts').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var taxAnnual = parseFloat(document.getElementById('propTax').value);
var insuranceAnnual = parseFloat(document.getElementById('insurance').value);
var hoa = parseFloat(document.getElementById('hoa').value);
var maint = parseFloat(document.getElementById('maintenance').value);
var vacancyPercent = parseFloat(document.getElementById('vacancyRate').value);
var mgmtPercent = parseFloat(document.getElementById('managementFee').value);
// Validate inputs
if (isNaN(price) || isNaN(rent) || isNaN(rate) || isNaN(term)) {
alert("Please enter valid numbers for Price, Rent, Interest Rate, and Loan Term.");
return;
}
// Handle defaults for empty optional fields
if (isNaN(closing)) closing = 0;
if (isNaN(taxAnnual)) taxAnnual = 0;
if (isNaN(insuranceAnnual)) insuranceAnnual = 0;
if (isNaN(hoa)) hoa = 0;
if (isNaN(maint)) maint = 0;
if (isNaN(vacancyPercent)) vacancyPercent = 0;
if (isNaN(mgmtPercent)) mgmtPercent = 0;
// 2. Mortgage Calculation
var downPaymentAmount = price * (downPercent / 100);
var loanAmount = price – downPaymentAmount;
var monthlyRate = rate / 100 / 12;
var numPayments = term * 12;
var monthlyPI = 0;
if (rate === 0) {
monthlyPI = loanAmount / numPayments;
} else {
monthlyPI = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
}
// 3. Operating Expenses Calculation
var monthlyTax = taxAnnual / 12;
var monthlyInsurance = insuranceAnnual / 12;
var monthlyVacancyCost = rent * (vacancyPercent / 100);
var monthlyMgmtCost = rent * (mgmtPercent / 100);
var totalMonthlyOperatingExpenses = monthlyTax + monthlyInsurance + hoa + maint + monthlyVacancyCost + monthlyMgmtCost;
var totalMonthlyExpensesWithMortgage = totalMonthlyOperatingExpenses + monthlyPI;
// 4. Income Metrics
var monthlyNOI = rent – totalMonthlyOperatingExpenses; // NOI excludes mortgage
var annualNOI = monthlyNOI * 12;
var monthlyCashFlow = rent – totalMonthlyExpensesWithMortgage;
var annualCashFlow = monthlyCashFlow * 12;
// 5. Return Metrics
var totalCashInvested = downPaymentAmount + closing;
var capRate = 0;
if (price > 0) {
capRate = (annualNOI / price) * 100;
}
var cocReturn = 0;
if (totalCashInvested > 0) {
cocReturn = (annualCashFlow / totalCashInvested) * 100;
}
// 6. Update UI
// Helper for formatting currency
var formatCurrency = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('monthlyCashFlow').innerText = formatCurrency.format(monthlyCashFlow);
document.getElementById('cocReturn').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('capRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('annualNOI').innerText = formatCurrency.format(annualNOI);
document.getElementById('totalExpenses').innerText = formatCurrency.format(totalMonthlyExpensesWithMortgage);
document.getElementById('mortgagePayment').innerText = formatCurrency.format(monthlyPI);
// Color coding for cash flow
var cfElement = document.getElementById('monthlyCashFlow');
cfElement.classList.remove('positive', 'negative');
if (monthlyCashFlow >= 0) {
cfElement.classList.add('positive');
} else {
cfElement.classList.add('negative');
}
}