Rental Property Cash Flow Calculator
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Rental Property Cash Flow Calculator
Purchase Information
Purchase Price ($)
Down Payment (%)
Interest Rate (%)
Loan Term (Years)
Rental Income
Monthly Rent ($)
Other Monthly Income ($)
Recurring Expenses
Property Tax (Annual $)
Home Insurance (Annual $)
HOA Fees (Monthly $)
Vacancy Rate (%)
Maintenance / CapEx (%)
Management Fee (%)
Calculate Cash Flow
Monthly Mortgage Payment (P&I):
Total Monthly Expenses:
Net Operating Income (NOI) / Mo:
Monthly Cash Flow:
Cash on Cash Return (Annual):
Cap Rate:
What is Rental Property Cash Flow?
Rental property cash flow is the net amount of money remaining after all expenses related to the property have been paid from the rental income. It is the lifeblood of any real estate investment. A positive cash flow means the property is generating profit month over month, while negative cash flow implies you are losing money to hold the asset.
Calculating cash flow accurately is critical before purchasing a property. Many new investors make the mistake of only subtracting the mortgage payment from the rent, forgetting to account for "hidden" costs like vacancy, maintenance, capital expenditures (CapEx), and property management fees.
How to Calculate Cash Flow
The formula for rental property cash flow is straightforward:
Cash Flow = Total Income – Total Expenses
Total Income: Includes monthly rent plus any additional income sources (laundry, parking, pet fees).Total Expenses: Includes Mortgage (Principal & Interest), Taxes, Insurance, HOA fees, Repairs, Vacancy reserves, and Management fees.
Understanding Key Metrics
Cash on Cash Return (CoC)
Cash on Cash return measures the annual return on the actual cash you invested, rather than the total purchase price. This is crucial for understanding the efficiency of your investment capital.
Formula: (Annual Cash Flow / Total Cash Invested) × 100
Cap Rate (Capitalization Rate)
Cap rate is used to evaluate the profitability of an investment assuming it was paid for in cash (no loan). It allows you to compare properties regardless of financing methods.
Formula: (Net Operating Income / Purchase Price) × 100
Real World Example
Let's say you buy a property for $250,000 with 20% down ($50,000).
Your rental income is $2,200/month .
Mortgage P&I: ~$1,264 (at 6.5% interest)Taxes & Insurance: ~$350/monthReserves (Vacancy/Repairs): ~$220/monthTotal Expenses: ~$1,834/month
Cash Flow: $2,200 – $1,834 = $366/month ($4,392/year).Cash on Cash Return: ($4,392 / $50,000) = 8.78% .
Using the calculator above allows you to tweak these variables to see how changes in interest rates, rent, or expenses impact your bottom line.
function calculateRental() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('purchasePrice').value);
var downPercent = parseFloat(document.getElementById('downPaymentPercent').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var rent = parseFloat(document.getElementById('monthlyRent').value);
var otherIncome = parseFloat(document.getElementById('otherIncome').value);
var annualTax = parseFloat(document.getElementById('annualTax').value);
var annualIns = parseFloat(document.getElementById('annualInsurance').value);
var monthlyHoa = parseFloat(document.getElementById('monthlyHoa').value);
var vacancyPct = parseFloat(document.getElementById('vacancyRate').value);
var maintenancePct = parseFloat(document.getElementById('maintenanceRate').value);
var managementPct = parseFloat(document.getElementById('managementFee').value);
// Validation to prevent NaN errors
if (isNaN(price) || isNaN(rent)) {
alert("Please enter valid numbers for Price and Rent.");
return;
}
// 2. Calculate Mortgage (P&I)
var loanAmount = price * (1 – (downPercent / 100));
var monthlyRate = (rate / 100) / 12;
var numPayments = years * 12;
var mortgagePayment = 0;
if (rate > 0) {
mortgagePayment = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
} else {
mortgagePayment = loanAmount / numPayments;
}
// 3. Calculate Monthly Expenses
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var totalMonthlyIncome = rent + otherIncome;
// Variable expenses based on percentage of income
var vacancyCost = totalMonthlyIncome * (vacancyPct / 100);
var maintenanceCost = totalMonthlyIncome * (maintenancePct / 100);
var managementCost = totalMonthlyIncome * (managementPct / 100);
var operatingExpenses = monthlyTax + monthlyIns + monthlyHoa + vacancyCost + maintenanceCost + managementCost;
var totalExpenses = operatingExpenses + mortgagePayment;
// 4. Calculate Key Metrics
var cashFlow = totalMonthlyIncome – totalExpenses;
var annualCashFlow = cashFlow * 12;
var noi = (totalMonthlyIncome * 12) – (operatingExpenses * 12);
var capRate = (price > 0) ? (noi / price) * 100 : 0;
var initialCashInvested = price * (downPercent / 100);
// Note: In a full calculator we would add closing costs here, but we use down payment as proxy for simplicity
var cocReturn = (initialCashInvested > 0) ? (annualCashFlow / initialCashInvested) * 100 : 0;
// 5. Display Results
document.getElementById('results').style.display = 'block';
document.getElementById('resMortgage').innerText = formatCurrency(mortgagePayment);
document.getElementById('resExpenses').innerText = formatCurrency(totalExpenses);
document.getElementById('resNOI').innerText = formatCurrency(noi / 12);
var cfElement = document.getElementById('resCashFlow');
cfElement.innerText = formatCurrency(cashFlow);
if (cashFlow >= 0) {
cfElement.className = "result-value positive";
} else {
cfElement.className = "result-value negative";
}
document.getElementById('resCoC').innerText = cocReturn.toFixed(2) + "%";
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
}
function formatCurrency(num) {
return "$" + num.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
}